2014 9th
Class Practicals Biology Important Topics
1. Study of different types of bacteria with the
help of prepared slides.
2. Study of Amoeba with the help of prepared
slides/fresh culture/charts.
3. Study of external structure of Mustard plant
(Brassica Campestris).
4. Identification of Jelly fish, Earthworm,
Starfish, Cartilaginous fish, class reptilian and
class mammalian from fresh and preserved
specimens based on salient taxonomic characteristics.
5. Microscopic observation of an animal cell
(from Blood of Frog) and plant cell (from
epidermis of onion).
6. Effect of tonicity on plasmolysis and
deplasmolysison plant cells or blood cells.
7. Effect of enzyme pepsin (invitro) on
meat/albumin.
8. Experiment for action of enzyme diastase on
Starch.
9. Experiment to show the process of
photosynthesis using aquatic plant Hydrilla.
10. Experiment to prove that Carbon dioxide is necessary
for photosynthesis.
11. Experiment to prove that respiration takes
place ingerminating seeds using lime water.
12. Food Tests:.
(i) Benedict’s Test for Glucose (reducing
sugars).
(ii) Iodine Test for Starch (non reducing
sugars).
(iii) Emulsion Test and Spot Test for fats.
(iv) Biuret Test for protein.
13. Estimation of loss of water from both
surfaces of leaf using Cobalt Chloride paper.
14. Observation of transpiration in a potted
plant keptunder a bell jar.
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Biology Chapter 3 - CLASSIFICATION OF LIVING
ORGANISMS Notes 2011-12
CLASSIFICATION OF LIVING ORGANISMS
Classification
The arrangement of organisms into groups and
subgroups on the basis of similar characters is called classification.
Basis of Classification
The classification of organisms is based on such
features or characters, which are similar in one kind of organisms and
different in different kind of organisms. These characters may be about
internal morphology, (anatomy), external morphology, physiology, cell
structure, especially the number of chromosomes and chemical composition
(especially of proteins) and embryology of the organisms. These characters help
in study of intra specific (within the same species) and intra specific
(between different) species differences. The presence of similar characters in
different organisms indicates their common ancestory. This similarity because
of common ancestral origin is called Homology e.g. arm of a monkey, flipper of
a whale and wing of a bat show homology. They are dissimilar apparently but
their internal structure (arrangement of bones and muscles) is same. These
organs are called homologous organs. Due to this homology, we can, say that monkey,
whale and bad had common ancestors and are placed in same large group
"vertebrate". This homology is proved to be very helpful in
classification.
Aims/Objectives of Classification
These are given below:
1. To determine similarities and differences
between different organisms.
2. To arrange organisms on the basis of
similarities and differences.
3. To identify the organisms on the basis of
their structure and other prominent characters and study them systematically
and logically.
4. To find out inter-relationships of organisms.
First of all, Aristotle classified the organisms
on the basis of their resemblances. After this, Theophrastus classified the
plants. Then, after a long time, Carolous Linnaeus (1707-1778), suggested a new
system of classification. In this way, he started modem taxonomy.
Units of Classification
The basic unit of classification is specie
(Plural specie). A species is a group of organisms that can breed with one
another in nature and produce fertile offspring. All members of a species have
same number of chromosomes and also have many other features in common. All the
mustard plants belong to one species. All the human beings belong to another
species. The members of one species differ from members of other species and do
not breed naturally with each other. Such different species, which are closely
related, they are grouped in large group called genus (plural; genera) e.g.
Brassica is a genus. It includes several species like mustard, cabbage and
turnip. Similarly, Felis is a genus. It includes several species like lion,
tiger and cat. Similarly, many closely related genera are placed in a bigger
group called Family, families are grouped into an order, orders are grouped
into a class and classes are grouped into a phylum (plural, phyla) or division
(plural; division) in case of plants. The phyla or divisions are grouped into
kingdom. All these units are divided into subunits e.g. sub genus, sub phylum
and sub kingdom etc. The smallest the group or unit, the organisms found in
this group, would be more similar, they have more number of of similar
character.
Difference between Homologous and Analogous
Organisms
The fruit of all plants, whether sweet, or sour,
small and dry or large and fleshy, all are the homologous structures because
they develop from ovary of flower. Their origin is common. On the other hand,
wings of an insect, and a bird, despite having same function, are not
homologous because their origin is different. Similarly green leaf of moss
plant and that of any vascular plant are not homologous. These organs are
similar in function but different in basic structure and origins are called
analogous organs.
Biological Classification of Mustard Plant
Common Name ----------------- Mustard
Phylum or Division ---------- Anthophyta
Class ----------------------- Dictyledonae
Order ----------------------- Capparales
Family ---------------------- Brassicaceae
Genus ----------------------- Brassica
Species --------------------- Brassica
Campestris
Classification of Human Beings
Common Name ---------------- Human
Kingdom -------------------- Animalia
Phylum --------------------- Chordata
Class ---------------------- Mammalia
Order ---------------------- Primates
Family --------------------- Hominidae
Genus ---------------------- Homo
Species -------------------- Homo sapiens
Scientific Name ------------ Homo sapiens
Kingdoms of Organisms
The classification is not static, nor has only
one system of classification been followed rather it is dynamic. Whenever any
new knowledge is available about organisms, it is used in classification.
Therefore, many systems of classification have been used. Living organisms are
classified into two to five kingdoms.
Two Kingdom Systems
All organisms were classified into two kingdoms
before present time.
1. Plant Kingdom (Plantae) - It includes all the
small and large plants.
2. Animal Kingdom (Animals) - It includes all
the animals.
Important Characters of Plants and Animals
Presence of cell wall and ability to prepare
their own food were considered the most important characters of plants.
Lack of cell wall and inability to prepare food
and characteristic mode of nutrition and especially the ability to locomote
were considered the most important characters of animals.
Plant kingdom and animal kingdom were divided into
large groups.
Binomial Nomenclature
The method of giving scientific names to
organisms is called nomenclature. Same animal or same plants may be known by
different names. It must have one scientific name so that there may be no
confusion. To give such names to living organisms, the method was formulated by
carolous Linnaeous (1753). This method is called Binomial Nomenclature. Because
tis system is simple and comprehensive, so it is accepted and used in whole
world.
Rules of Binomial Nomenclature
1. According to this method, every species of
living organisms is given a Latinized scientific name consisting of two parts.
2. The first part is the name of genus and is
called generic name. It starts with a capital letter.
3. The second part is the name of species and is
called specific name. It starts with a small letter.
4. Both parts of scientific name of a species
are either underlined separately or italicized.
The scientific name of mustard plant is Brassica
campestris. The scientific name of rose plant is Rose indica. Similarly the
scientific name of frog is Rana tigrina and that of human is Homo sapiens.
Significance of Binomial Nomenclature
Before establishment of binomial nomenclature,
the names of organisms consisted of many words. These words were based on the
characters of these plants or animals. In different countries, even in
different parts of same country; local names were used for plants and animals.
The same organism may be given different names e.g. turnip, shaljam, gongloo,
thipar, and gogroon are all names of same plant. In England, there are at least
fifty names for pansy. Similarly a single common name may be used for different
kind of organisms e.g. the word "raspberry" is used for about 100
kinds of plants. This confusion can be avoided by giving each organism a
scientific name according to binomial nomenclature proposed by Carolous
Linnaeus in 1753. It is adopted by all taxonomists.
Biological Classification of Man
Common Name ----------------- Man
Kingdom --------------------- Animalia
Phylum ---------------------- Chordata
Class ----------------------- Mammalia
Order ----------------------- Primates
Family ---------------------- Hominidae
Genus ----------------------- Homo
Species --------------------- Homo sapiens
Biological Classification of Frog
Common Name ----------------- Frog
Kingdom --------------------- Animalia
Phylum ---------------------- Chordata
Class ----------------------- Amphibia
Order ----------------------- Salientia (Anura)
Family ---------------------- Ranidae
Species --------------------- Rana tigrina
9th Class Biology Notes 2011-12 - INTRODUCTION OF
BIOLOGY
Chapter 1
INTRODUCTION OF BIOLOGY
SCIENCE.
Our universe operates under certain
principles. For understanding of these principles, the experiments are done and
observations are made; on the basis of which logical conclusions are drawn.
Such a study is called "Science". In brief science is the knowledge
based on experiments and observations.
BIOLOGY.
The Scientific study of living organisms is
called Biology. The word biology is derived from two Greek words
"bios" meaning life and "logos" meaning thought, discourse,
reasoning or study. It means that all aspects of life and every type of living
organism are discussed in biology. Branches of Biology
Biology is divided into following branches:
Morphology
The study of form and structure of living
organisms is called morphology. It can be further divided into following two
parts:
1. The study of external parts of living
organism is called external morphology.
2. The study of internal parts of living
organism is called internal morphology or anatomy.
Histology
The study of cells and tissues with the aid of
the microscope is called Histology.
Cell Biology
The study of structure and functions of cells
and their organelles is called Cell Biology.
Physiology
the study of different functions performed by
different parts of living organism is called Physiology.
Ecology
The study of organisms in relation to each other
and their environment is called Ecology or Environmental Biology.
Taxanomy
Living organisms are classified into groups and
subgroups on the basis of similarities and differences. This is called
classification Taxanomy is that branch of biology in which organisms are
classified and given scientific names.
Embryology
The study of development of an organism from
fertilized egg (zygote) is called embryology. The stage between zygote and
newly hatched or born baby is called embryo.
Genetics
The study of methods and principles of
biological inheritance of characters from parents to their offspring is called
genetics.
Paleontology
The body parts of ancient organisms or their
impressions preserved in rocks are called fossils. The study of fossils is
called paleontology. It also includes the study of origin and evolution of
organisms.
It can be divided into two parts:
1. The study of fossils of plants is called
Palaeobotany.
2. The study of fossils of animals is called
Palaeozoology.
Biochemistry
The study of metabolic reactions taking place in
living organisms is called biochemistry. These reactions may be constructive or
destructive. The assimilation of food is a constructive process and respiration
is a destructive process.
Biotechnology
It is the branch of biology which deals with the
practical application of organisms and their components for the welfare of
human beings e.g. disinfections and preservations of food, preservations of
insulin and biogas from bacteria etc.
Relationship of Biology with other Sciences
In ancient times, there was no distinction of biology
and other sciences. Different fields of sciences like biology, chemistry,
physics and mathematics are met together in the writings of ancient scientists.
In ancient times, these subjects were studied under one head
"science", but with the passage of time, the science developed very
much and the huge scientific knowledge was then divided into different
branches.
Biophysics
The study of various biological phenomena
according to principles of physics is called biophysics. For example, movement
of muscles and bones based on principles of physics.
Biochemistry
The study of different biochemical like
carbohydrates, proteins and nucleic acids etc found in cells of living
organisms and hundreds of the underlying chemical reactions in cells of
organisms is called biochemistry.
Biometry
The data obtained from observations and
experiments on living organism is analyzed by various statistical methods. This
is called Biometry.
Biogeography
The study of plants and animals and the basis of
geographical distribution is called Biogeography.
Bio-Economics
The study of living organisms from economic
point of view is called Bio-Economics. It includes the study of cost
effectiveness and viability of biological projects from commercial point of
view.
Biological Method of Study or Method Used to
Solve the Problem of Malaria
Observation
Most of the biological investigations start with
an observation. After selecting, specific biological problem, observations are
made to collect relevant information. For example; take the case of Malaria.
Malaria is the greatest killer disease of man for centuries. Malaria was one
among many other diseases for which a cure was needed.
In 1878, A French physician, Laveran, studied
the blood sample of Malaria patient under microscope and observed tiny
creatures in it. These creatures were later called Plasmodium.
Hypothesis
To solve a scientific problem, one or more
possible propositions are made on the basis of the observations. Such a
proposition is called a Hypothesis. The hypothesis is tested by scientific
method.
Merits
A good hypothesis has the following merits:
1. It is close to the observed fact.
2. One or more deductions can be made from this.
3. These deductions should be confirmed doing
experiments.
4. Results whether positive or negative should
be reproducible.
To know the cause of malaria, following
hypothesis was made:
Plasmodium is the cause of Malaria."
Note: One or more than one possible deductions
can be made from the hypothesis.
Deduction
the logical conclusion drawn from a hypothesis
is called deduction. Testing one deduction and finding it correct does not
necessarily mean the hypothesis is correct and scientific problem is solved.
Actually, if more deductions are found to be correct; the hypothesis will be
close to solution of the problem.
Experiments
Following groups are designed to perform
experiments:
Experimental Group
It is the group of those people who are affected
in some way and we do not know the real cause e.g. a group of malarial
patients.
Control Group
It is the group of unaffected people e.g.
persons group of healthy persons.
By keeping both of these groups under similar
conditions, the difference between them is determined. To know the real cause
of malaria, the experts examined the blood of about 100 malarial patients
(experimental group). On the other hand, the experts examined the blood of
about 100 healthy persons (control group).
Results
During the experiments mentioned above; the
plasmodium was found in blood of most of malarial patients. The plasmodim was
absent in the blood of healthy persons. These results verified the deductions
and thus the hypothesis i.e. the plasmodium is the cause of Malaria, was proved
to a considerable extent.
Theory
If hypothesis is proved to be correct from
repeated experiments and uniform results, then this hypothesis becomes a
theory.
Scientific Principle
When a theory is again and again proved to be
correct, then it is called a scientific principle.
Contributions of Muslims Scientists in the Field
of Biology
Many Muslim scientists contributed a lot in the
field of biology but the following names are more respectable:
Jabar-Bin-Hayan
Period: 722-817 A.D
Books: Alnabatat and Alhaywan
Contribution: He studied the life of plants and
animals and wrote many books about them.
Abdul-Malik-Asmal
Period:741 A.D
Books: Al-Kheil, Al-Ibil, As-Sha, Al-Wahoosh,
Khalaqul Insan.
Contributions: He described the body structure
and functions of horses, camels, sheep, wild animals and human beings in
detail.
Abu-Usman-Umer Al-Jahiz
Books: Al-Haywan
Contribution: He explained the characteristics
of about 350 species of animals. He wrote on the life of aunts especially.
Al-Farabi and Abu-ul-Qusim Al-Zahravi
Period: 870-950 A.D
Books: Al-Nabatat, Al-Haywanat
Contribution: The above mentioned books were
written by Al-Farabi. On the other hand, Al-Zahravi was famous for removal of
stone from urinary bladder.
Ibn-ul-Haitham
Period: 965-1039 A.D
Books: Al-Manazir, Mizan-ul-Hikma
Contributions: Both of these books were famous
and well known at that time. These books were translated into Latin, Hebrew,
Greek and other western languages. He explained the structure and functions of
eyes and suggested the cornea as a site of vision.
Bu-Ali Sina
Period: 980 A.D
Book: Al-Qanoon Fil Tib Al-Shifa
Contribution: He wrote about plants, animals and
non-living things in one book. He was expert in mathematics, astronomy, physics
and paleontology.
Ibn-ul-Nafees
Contribution: he described the blood circulation
in the human body.
Ali Ibne Isa
Contribution: He worked on structure, functions
of eye and about 130 diseases of eyes and their treatment.
Non-Muslim Scientists
There is long list of non-Muslim scientists who
contributed a lot in the field of biology. But, the following scientists are
very well known.
Aristotle
Period: 382-322 A.D
Book: Historia Animalia
Contribution: He classified the animals and
called as founder of biological classifications. He classified animals into two
units, genus and species which was called Oedos.
Theophrastus
Contribution: He accepted *** in plants and
desired about 500 plants. He is known as father of botany.
Visalius
Period: 1514-1564 A.D
Contribution: He wrote a book on human body
structure in which he described bones, muscles and orans in detail.
William Harvey
Period: 1578-1657 A.D
Contribution: He described the blood circulation
in human body.
Carolous Linnaeus
Period: 1507-1778 A.D
Contribution: He described the blood circulation
in human body.
Carolous Linnaeus
Period: 1578-1657 A.D.
Contribution: He gave a system of binomial
nomenclature. He is known as father of taxonomy.
Schlelden and Schwann
Contribution: Scheiden (1838) studied the cells
of plants and Schwann (1839) studied the cells of animals. They proposed the
cell theory.
Louis Pasteur
Period: 1822-1895 A.D
Contribution: He proved that microbes are found
in the air which spoils the food items.
Edward Jennar
Period: 1796 A.D
Contribution: He invented method of vaccination
against Small Pox.
Robert Koch
Period: 1845-1910 A.D.
Contribution: He discovered bacteria as causes
of main diseases like Tuberculosis.
Joseph Lister
Period: 1860 A.D
Contribution: He made antiseptic medicines like
Iodine and Carbolic acid.
Charles Darwin
Period: 1859 A.D
Book: Origin of Species by Natural Selection
Contribution: He explained concept of evolution
in his book.
Gregor Mendel
Period: 1822-1884 A.D
Contribution: He conducted experiments on Pea
plants. He formulated the laws of inheritance. He is known as father of modern
genetics.
William Lawrence and William Henry
Period: 1882 A.D
Contribution: They discovered X-ray
crystallography to understand the structure of deoxyribonucleic acid (DN). They
were father and son.
Francis Crick and James Watson
Period: 1953 A.D
Contribution: He discovered the double helix
model of DNA and proved that DNA is found in cells of all living organisms.
Significance of Biology or Impact of Biological
Study on Human Life
the present high level achievements of man are
largely due to the advanced biological research. The study of biology is very
important in routine matters of our life as described below.
Food Production.
Food has basic importance in our life. Due to
researches in biology, there are great achievements in agriculture. For the
production of cereal crops; the best varieties of seeds were selected. The
yield of wheat corn, rice, sugarcane and cotton has been enormously increased
bringing healthy effect and prosperity. Today, the man has overcome the
problems of balanced diet, food storage and famine.
Control on Diseases.
Health is basic necessity of life. Due to
researches in biology, the discovery of new antibiotics for many infectious
diseases like plague, cholera, pneumonia, tuberculosis and typhoid has made the
life easy. The infant mortality has reduced due to discovery of vaccines for
fatal diseases like small pox, polio, tetanus and diphtheria. Today AIDS is
problem for world. The germs of this disease destroy the natural resistance and
immunities against diseases.
A medicine called AZT has been found effective
for AIDS. Similarly many drugs have been discovered for treatment of cancer.
Many organisms are used to produce drugs e.g. bacteria and fungi. We have
controlled many infectious diseases by using drugs like penicillin and
streptomycin. We have eliminated many harmful pests like locusts, flour beetle,
termites, fungi, shipworm etc by using pesticides.
Genetic Engineering.
Genetic engineering is a technology in which
useful genes are inserted into the bacteria etc, to get required beneficial
results. Using this technique, manipulation of heredity material is done and
new species are produced e.g. Doli sheep. Today human insulin gene is inserted
into DNA of bacteria to synthesize insulin on commercial bases. This insulin is
found to be very useful in treatment of diabetic patients.
Pollution Control.
Due to increasing urbanization,
industrialization and automobiles, the man and other organisms have to face a
great danger, "the environmental pollution". due to pollution of air,
land and water there is danger to humans aid wild life. Many plants and animals
have been maintaining the balance in our environment for millions of years and
now at the verge of extinction due to pollution. By biological research,
scientists are busy to find out causes and ways to control the pollution. The
biology thus, has greatly improved the quality of our life.
Space Biology.
On Mars, some evidence of life has been found
which is still under further investigation. During exploration of space the
scientists have been conducted experiments on different plants, animals, fungi
and bacteria in space and they have obtained very useful information.
Islamic concepts About Origin of Life
We have got much information about origin of
life by studying the Holy Quran.
Ultimate Creator
The first thing learnt from teachings of Quran
is that Allah is the ultimate creator of everything whether plants, animals or
non-living things.
"Allah is the creator of all things and He
is Guardian of overall things." - (Surah Zamar-Ayat62)
Not only plants, animals and non-living things
and human beings but also the heavens and whole universe have been created by
Allah.
Origin of Life from Water
The second important fact we get from Quran is
that Allah has created all living thins from water.
"We made every thing from water." -
(Sura Ambia - Ayat 30)
Viruses, bacteria, algae, fungi, different
plants, all animals and humans are all living things. According to Quranic
verses, all diverse living things were created from water.
Common Origin
From above mentioned sayings of God there is an
indication for common origin of living things or we can at least say that all
living things have come out from water.
Creation of Man
Allah also sys in Quran:
"He created man from clay like the
potter's." - (Sura Rehman - Ayat 14)
It seems that there were following two sages for
creation of man:
1. Creation from water.
2. The first created thing, on admixing with
clay was transformed into more advanced beings.
The same can also be applied to other animals
because there are certain similarities between structure of man and other
animals. In vertebrate animals, the structures of digestive system, respiratory
system, blood circulatory system, excretory system and reproductive system etc
are similar to great extent, although differ in other details. Reproduction in
living things.
Once the life had been created, Allah
implemented the process of reproduction for the continuity of races of animals
and other organisms. The various stages of reproduction have been described in
sura in following way:
"Then fashioned we drop a clot, then
fashioned we clot a little lump, then fashioned we the lump bones, then clothed
the bones with flesh." - (Sura Almominoon Ayat 14)
Classification and Evolution
"Allah has created every animal from water
some of them creep up on their bellies, other walk on two legs, and others on
four, Allah creates what the pleases. He has power overall thins." - (Sura
Nur Ayat 45)
"Hath there come upon man (every) any
period of time in which he was a thing unrememberd?" - (Sura Dahar Ayat 1)
The close study of above sayings of God reveals
that all animals had a common origin but they gradually underwent changes after
words and became different from each other i.e. some animals became crawler,
some bipedal and some other tetra pods. The present animals are advanced forms
of the past animals who achieved this form after passing through many changes.
Concept of Abiogenesis and Biogenesis for Origin
of Life on Planet Earth
Scientific Views About Origin of Life
How did life originate on this earth? This may
never be know for certain to science because neither it is possible today to
make observation of primitive events when the life actually originated nor
there is any fossil record of first formed soft bodied organisms. However, in
1950 some scientists created the primitive earth condition (approximately 4
billion years ago) in the laboratory and performed experiments. On the basis of
results obtained from these experiments, scientists formulated some ideas.
These ideas seem to be close to reality.
Abiogenesis and Biogenesis
In ancient times, there were two views about the
origin of life:
1. According to one view, offspring are produced
from their parents by process of reproduction, this is called concept of
Biogenesis.
2. According to other view, living things are
produced spontaneously from non-living things. This is called concept of
Abiogenesis.
Because at that time, there was neither so much
advancement in science nor scientific tools like microscope and other
instruments were invented, which could help in detailed observations about
reality. According to some people, insects are produced from dewdrops, rats
from debris, frogs from mud, and maggots from putrefied meat. Some scientists
like Copernieus, Bacon, Galileo, Harvey, and Descartes also believed this
concept.
From 16th to 18th century many scientists
performed experiments to test this concept. They found some animals to be
developed from non living matter. Therefore this concept seemed to be correct.
Later on, scientists performed experiments with
more care. First of all an Italian scientists, Francesco Redi, (1668) proved
that this concept was wrong.
Redi's Experiment
Redi took four bottles. He put a dead snake in
one bottle, a few dead fish in second bottle, dead eel in third bottle and a
piece of meat in the fourth bottle. All these bottles were left open. The flies
could enter these bottles. Then he took four more such bottles. He put some
dead animals in all four bottles but covered the mouth of bottles.
(Figure from book)
After few days, maggots were produced in four
open bottles. Maggots were not produced in closed bottles. Moreover, no flies
were seen. Therefore, it was proved that maggots were not produced
spontaneously by produced due to flied which were visiting the open bottles.
The maggots were the larvae produced from the eggs of the visiting flies.
Needham's Experiment
In 1948, an English scientist Needham boiled the
meat in the water and prepared gravy. He poured this gravy into the bottles and
closes their mouth with corks. After some days, many microscopic organisms were
produced. In this way, the believers of abiogenesis were once again gain
courage.
Experiment of Spallanzani
In 1767, an Italian scientists Spallanzani
criticized the experiment of Needham. He said that air entered the bottles
through the pores of cork and hence living organisms were produced.
(Figure from Book)
Spallanzani put the boiled meat and vegetables
in clean bottles and then sealed the mouth of bottles by heat. He placed these
sealed bottles in boiled water to kill the possible germs. After some days, he
found no organisms. He left the same boiled meat and vegetables in open bottles
at the same time. Some living organisms were produced in these bottles. This
supportd the concept of Biogenesis. But the believers of Abiogenesis said that
air removed by Spallanzani was necessary for living things so no organisms were
produced in sealed bottles. When oxygen was discovered the supporters of
Abiogenesis said that Spallanzani had removed oxygen where by no life could be
produced in his experiment.
Experiment of Louis Pasteur
The argument on Biogenesis and Abiogenesis
continued up to the middle of, 19th century. A well-known French scientist,
Louis Pasteur proved, after simple but very careful experiments, that
abiogenesis could not occur in present environment of earth. He proved that
living organisms could only be produced from their parents.
In 1864, Pasteur performed his experiment in
front of the commission formed to solve the issue. He took flasks, which had
long curved S-shaped necks. He placed fermentable infusion (Yeast + sugar +
water) in flasks and left their mouth open.
(Figure from Book)
He boiled the yeast infusion in the flasks.
After this, he allowed to cool them and kept them as such. He observed that no
life ws produced even after the lapse of several days, because microscopic
organisms entering along with air got stuck up in on the curved walls of the
glass necks. Then he broke up the curved necks, so that air containing
microscopic organisms could reach the infusion. Now he noted that microscopic organisms
were produced within 48 hours. This proved that if care was taken and no
microscopic organisms and reproductive structures (eggs or spores) approach the
infusion, no life could be produced because thee is no spontaneous generation
of life from non life. After Pasteur, no further experiments were performed on
origin of life for the next 60 years. In 1920, a Russian biochemist Alexander
Oparin and a British biologist J.B.S 1-Ialdane suggested that life on earth was
originated after a long and gradual molecular evolution and there was no
spontaneous and miraculous origin of life on earth.
Chemical and Organic Evolution of Life on Earth
The modern view of the origin of life stresses
on the idea of chemical evolution. According to Oparin and Haldane, the origin
of first life had been initiated from the time of the existence of the solar
system (the sun with its nine planets). The earth, like the sun was made up of
light and heavy elements. Heavy elements like iron, nickel etc were present in
the nucleus of the earth, while the light elements and compounds like hydrogen,
methane, nitrogen, carbon, ammonia, nitrogen oxide, etc in the form of vapours
existed on the surface of the earth. These light elements and compounds were
responsible for the first life on earth.
The earth had high temperature and radiation and
had frequent and abundant discharges. In these conditions, the first life
originated. Oparin and Haldane suggested that simple inorganic molecules slowly
and gradually combined to produce complex organic molecules from which the
simplest form of life (bacteria) came into existence. This process took a long
time.
Haldane proposed that primitive earth's
atmosphere had only carbon dioxide, ammonia and water vapours. If a mixture of
these gases is exposed to ultraviolet radiation, it leads to the formation of
organic compounds like sugar and amino acids. As free oxygen was not available
to check the radiation from reaching the earth so substances like sugar and
amino acids went on accumulating under such conditions.
About 15 billion years ago, there was a huge
explosion (Big Bag). The universe started expanding and the temperature dropped
drastically. In time, about 4.6 billion years ago our earth and other planets
appeared as part of the solar system. The primitive atmosphere of the earth was
rich in hydrogen.
With the passage of time, the atmospheric
temperature gradually dropped. This allowed condensation and heavy rains, which
caused formation of oceans. Thunder and lightning sparks together with
ultraviolet radiation caused reactions of the atmospheric gases resulting in
the formation of simple organic molecules. These molecules came down with the
rains and accumulated in the seas, oceans, lakes, rivers and the soil over a
very long period of time. These molecules interacted and produced amino acids
and proteins which are the body building substances.
The fossil evidence indicates that the earliest
forms of organisms lived about 3.8 billion years ago. From this it is
speculated that the origin of life started about 4 billion years ago.
The earliest organisms were heterotrophs. The
depletion of the pre-existed food from the environment led to the evolution of
organisms capable of making their own food. They became autotrophs, and added
free
oxygen into the atmosphere.
For at least the first 2 billion years of life
on earth, all organisms were bacteria. About 1.5 billions years ago, the first
eukaryotes appeared.
The idea of organic evolution was supported by
scientists like Lamarck and Charles Darwin.
Differentiate between Biogenesis and Abiogenesis
Biogenesis
A theory which describes the origin of life on
the earth from pre-existing living organisms is called Biogenesis.
(i) It was based on practical experiments and
material evidence.
(ii) It was supported by the experiments
performed by Redi and Pasteur.
(iii) It was based on practical basis.
(iv) It describes the process of reproduction as
an essential ability of living organisms.
Abiogenesis
A theory which describes the origin of life on
the earth from non living things is called Abiogenesis.
(i) It was based on observations and national
thoughts.
(ii) It was supported by the fungus of bread:
and production of frogs in the mud.
(iii) It was based on theoretical basis.
(iv) It gives no scientific reasoning about the
production of life.
Differentiate between Hypothesis and Theory
Hypothesis
(i) The process of making some possible answers
for the related biological problem is called Hypothesis.
(ii) It is the step of biological methods which
gives the way to carry on the research.
(iii) Hypothesis is an uncertain intelligent
statement.
(iv) Hypothesis is formed from observations and
collected facts.
Theory
(i) The final explanation which is given on the
basis of hypothesis and deduction if they are found correct is called theory.
(ii) It is the step of biological method which
gives actual reason to biological method.
(iii) Theory is certain intelligent statement.
(iv) Theory is formed by experimentation,
physical evidence to explain the laws of nature
NOTES OF BIOLOGY FOR CLASS IX
Introduction
to Biology
Biology
Biology is the branch of science which deals
with the study of living organisms. The terms Biology is derived from two Greek
words "Bios" means life and "Logos" means knowledge. Thus
biology is science of life. It is an organized study of living things and of
the theories that men have devised to describe and explain the world of life.
Branches of Biology
Branches of Biology
1. BOTANY The branch of biology which deals with
the study of plants.
2. ZOOLOGY The branch of biology which deals
with the study of animals. Some of the important branches of biology common to
botany and zoology are:
a. MORPHOLOGY It deals with the study of
external structures of animals and plants.
b. HISTOLOGY It deals with the study of tissues
of plants and animals under microscope.
c. CYTOLOGY It is the study of the cell and its
organ.
d. PHYSIOLOGY It is the study of working of
various systems of living organisms.
e. ECOLOGY It is the study of relationship of
living organisms with their environment.
f. TAXONOMY The branch which deals with
classification and naming of living organisms.
g. GENETICS It deals with the study of
inheritance of character from one generation to another.
h. MICROBIOLOGY It deals with the study of
microscopic organisms such as virus, bacteria and protozoans.
i. BIOTECHNOLOGY It deals with the application
of biological processes for the benefit of mankind.
Biological Methods
Biological Methods
Although biology is a distinct branch of
science, its method is similar to that of its other branches. Following are the
steps involved in investigation of biological phenomenon.
IDENTIFICATION OF PROBLEM At first problem
should be identified.
COLLECTION OF THE DATA ON THE BASIS OF
OBSERVATION Fact are collected related to specific problem. HYPOTHESIS It is
scientific guess on the basis of observation. It needs experimental
verification.
EXPERIMENTATION The proposed hypothesis is
examined by experiments designed especially for this purpose. THEORY If
hypothesis is verified by experiments it is given a status of theory.
Malaria
Malaria
Malaria has been a big problem for man for
centuries.
SYMPTOMS OF MALARIA Shivering due to chill
followed by very high fever. The patient sweats his breath and respiratory rate
increases.
THE HISTORY OF MALARIA Malaria was one among
many other diseases for which cure was needed. Although no cure was found for
malaria by Greeks, when Romans took over from them, they made a simple
observation. Malaria was common among people living near marshes. In fact the
word malaria is of Roman origin, "Mala" means bad and
"aria" means air. The Romans thought that the bad air of the marshes
was poisonous and caused malaria.
In 1878, a French physician Luhveran discovered
Plasmodium in the sample of blood of patient suffering from malaria. It was
soon found that plasmodium is present in the saliva of female Anopheles
mosquito. When it bites a human it transfers plasmodium into his blood and
cause malaria.
Female anopheles ¾ ¾® Human being ¾ ¾ ® Malaria
The human efforts in the field of medicinal plants led to the discovery of
Quinine from cinchona plant. Now a days it is easily careable disease.
Muslim Biologists
Muslim Biologists
ABDUL MALIK ASMAI:
He was born in Busra in 741 AD he was regarded
as specialist of this time in animal science.
PUBLICATION
He wrote many books on animals and plants.
Following are the names of his famous books:
Al - Kheil:About horses
Al - Ibit:About camels
As - Shat:About sheep
Al - Wahoosh:About wild animals
Khalaqul Insan:About different parts of human
body
ALI BIN RABBAN TUBRI:
He was born in 775 A.D in Tubristan and died in
870 AD.
PUBLICATION
FIRDUS - UL - HIKMA
The book has many illustrations and detailed
articles on objects like philosophy, zoology, psychology and astronomy.
AL - FARABI
(870 - 950 AD)
He was renowned Hakim of Islamic world.
PUBLICATION
He wrote two well known books.
Kitab - i - Nabatiat
Kitab - ul - Haywanat
ABUL QASIM AL - ZAHRAVI
(936 - 1004 AD)
He was renowned surgeon of the Islamic world. He
was famous for the removal of stone from the urinary bladder.
IBN - AL - HAITHAM (965 - 1039 AD)
He is one of the most outstanding figures of
Muslim history, being an optician of great merit and stature. Some 200
scientific works said to have been written by him
on diverse subject. He was the first on to correct the Greek conception of
vision, locating retina as the seat of vision.
PUBLICATION
Kitabul Manazir
Mizanul Hikma
BU - ALI - SINA
He was born in Kharmsheen near Bukhara in 10th
century AD. He was considered to be one of the founders of medicine.
Aside from medicine he was expert in
mathematics, astronomy, physics, paleontology and music.
ZIA - UD - DIN IBN BAITAR
Zia-ud-din Ibn Baitar of 13th century
specialized in the study of plants. He was highly respected among the
scientists of
the middle age.
IBN - AL - NAFEES
He described the blood circulation during 13th
century.
KAMAL - UD - DIN AL DAMIRI
He was the greatest zoologist of his time. He
compiled a book "Hayat-al-Haywan" during the 14th century which was
about
thousand kinds of animals.
ALI BIN ISA
He was a well known eye specialist of his times
and worked on structure, function and diseases of eye. He wrote three
volumes on this subjects in which he has
described 130 diseases of the eye.
ABUL QASIM MAJREETI
He is especially known in Europe for his book on
animal species.
AL - JAHIZ
He wrote a famous book "Al-Haywan". In
this book he described his own observations on animals.
MUSLIM BIOLOGISTS
(i) Name: Abdul Malik Asmai
Period: 741 AD
Publication: Al-Khail
Al-Ibit As-shat Al-Wahoosh Khalaqul Insan
Topic:
Horses Camels
Sheep Wild animals Human body.
(ii) Name: Ali Bin Rabban Tubri
Period:775 - 870 AD
Publication: Firdus-ul-Hikma
Topic: Philosophy,Zoology Psychology astronomy
(iii) Name: Al-Farabi
Period: 870 - 950 AD
Publication: Kitab-ul-Haywanat Kitab-ul-Nabatiat
Topic: Animals,Plants
(iv) Name: Abul Qasim Al Zahravi
Period: 936 - 1004 AD
(v) Name: Ibn-al-Haitham
Period: 965 - 1039 AD
Publication: Kitab-ul-Manazir, Mizan-ul-Hikma
Topic: Eye
(vi) Name: Bu-Ali-Sina
Period: 10th century AD
(vii) Name: Zia-ud-din Ibn Baitar
Period: 13th century AD
(viii) Name: Ibn-al-Nafees
Period: 13th century AD
(ix) Name: Kamal-ud-din Al-Damiri
Period: 14th century AD
Publication:Hayat-ul-Haywan
Topic: Animals
Quranic Teachings about Animal and Plant Life
Quranic Teachings about Animal and Plant Life
It says about the origin of life that
"We made from water every living thing.
Will they not then believe?"
(Sura Anbiyah 21, Ayah 30)
"And Allah has created every animal from
water. Of them these are some that creep on their bellies. Some that walk on
two
legs and some that walk on four. Allah creates
what he pleases. He has power over all things."
(Sura Nur 24, Ayah 45)
"He sends down water from the sky and with
it brings forth the buds of every plant. From these we bring forth green
foliage and
close-growing grain, Palm-trees laden with
clusters of dates with in reach, vineyards and olive groves and pomegranates
(which are)
alike and different. Behold their fruits when
they bear fruits and ripen surely. In these there are sign for true
believers."
(Sura Anam 6, Ayah 99)
"He has made for you the earth like a
carpet spread out, has enabled you to go about there by roads and channels, and
has send
down water from the sky. With it we have
produced diverse pairs of plants each separate from the other."
(Sura Ta-Ha 20, Ayah 53)
"And in the earth are tracts and diverse
though neighboring, garden of vines and fields sown some with corn and palm
trees -
growing out of simple roots or otherwise.
Watered within the same water. Yet some of them we make more excellent than
others
to eat."
(Sura Al Ra’d 13, Ayah 4)
"It is Allah who splits the seeds and the
fruit stone. He brings forth the living from the dead, and the dead from the
living. How then
can you turn away from him."
(Sura Anam, Ayah 95)
"And virly in cattle too ye find an
instructive sign. From what is with in their bodies, between excretion and
blood, we produce for
you drink milk pure and *** to those who drink
it."
(Sura Nahal 16, Ayah 66)
"We have spread out the earth and set up on
it immovable mountains. We have caused to grow in it from every ordained
things."
(Sura Hajar 15, Ayah 19)
"Glory be to him who created pairs of all
things which the earth grown and of their own kind and that of which they have
no
knowledge."
(Sura Yasin 36, Ayah 36)
"And your Lord taught the bee to build its
cells in hills, on trees and in men’s habitations.
"Then to eat of all the produce (of earth)
and find with skills the spacious path of its Lord, their issue from within
their bodies a
drink of varying colours, wherein is healing for
men. Varily in this is a sign for those who give thought."
(Sura Nahal 16, Ayah 68-89)
Significance of Biology
Significance of Biology
Biology helps us to understand our lives and the
world we live in, it has made an enormous impact on human welfare.
Following are the points on importance of
biology.
An ever increasing human population require more
and more food. Food production can be increased by careful study
of plants and soil and improved techniques in
animal husbandry.
Biology has enabled man to realize the
importance of balanced diet. Biological studies have also helped to control
pest.
It is through advancement in biology that man
has able to control diseases with the consequence that mortality rate
has decreased and individuals live longer and
lead healthy lives.
In the field of health the discovery of
antibiotics and vaccines is note worthy. These remedies have been revolutionary
in controlling epidemic diseases.
Zoology, Botany
Fill in the Blanks
Fill in the Blanks
Biologyis the study of living organisms.
The word biology is combination of two Latin
words Bios and Logos.
The word malaria is of Roman origin Mala means
bad and aira means Air
Antony van Leenwenhock in Holland invented first
microscope in 1960
Bacteria was discovered in 1776
Luhveran Plasmodium was discovered by French
physician in 1878.
Anopheles Plasmodium is transmitted to man by
female,mosquito.
Cinchona Malaria is treated by Quinine obtained
from plant.
Malaria is caused by a protozoan Plasmodium
Botany is the branch of biology which deals with
the study of Plants
Zoology is the branch of biology deals with the
study of Animals
Morphologydeals with the study of external
structures of living organisms.
Histology deals with the study of tissues.
Cytology deals with the study of cells.
Physiology deals with the study of working of
different systems of living organisms.
Ecology deals with the study of relationship of
living organisms with their environment.
Taxonomy deals with the naming and
classification of living organisms.
Genetics deals with the inheritance of
characters from one generation to another.
Microbiology is the study of microscopic
organisms.
Biotechnology deals with the application of
biological processes.
Ali bin Isa was a well known eye specialist of
his time.
The famous book Al-Haywan was written by Al -
Jahiz
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Biology Complete Fill In The Blanks Impotent 2011-12
Complete the following sentences with
appropriate answers:
1. Cell was discovered in 1665 by _________.
2. Fungi cannot make their own food because they
lack _________.
3. The physical and chemical breakdown of food
in humans first begins in the _________.
4. During respiration _________ is released from
food.
5. The different parts of human body and their
functions are described in the book _________ written by Abdul Malik Asmai.
6. The study of tissues is called _________.
7. The hormone insulin is secreted by _________.
8. Tape-worm belongs to the phylum _________.
9. The fourth whorl of a flower is known as
_________.
10. Stem increases in thickness due to
_________.
11. The distance between two nodes of a stem is
called _________.
12. “Al-Mansoora” is written by _________.
13. The third eyelid (transparent membrane) that
protects the eye of frog in water is known as _________.
14. The organs of locomotion in _________ are
called Setae.
15. _________ supplies blood to the brain and to
the parts associated with the brain of forg.
16. The genes representing a pair of contrasting
characters are called _________.
17. Firdous-ul-Hikma is written by _________.
18. Star-fish belogns to the phylum _________.
19. Androecium is the _________ whorl of a
flower.
20. Goitre is caused by the deficiency of
_________.
21. Fish respires by means of special structures
called _________.
22. _________ controls all functions of a cell.
23. A long narrow and cylindrical fruit of
Brassica compestris is called _________.
24. The transfer of pollen grains from another
to the stigma of carpel is called _________.
25. Excretory organs in insects are called
_________.
26. The single major contribution of Muslim
scientists in the field of scientific method is use of _________.
27. The two main subdivisions of biology are
_________ and _________ each of which has several further branches.
28. Life can be best defined by comparing
_________ of living things with those of _________ things.
29. When food is burnt in our cells in the
presence of oxygen to produce energy the process is called _________.
30. When a cell divides to produce two new cells
exactly like the parent the process is called _________.
31. The sum of chemical reaction in cells is
called _________.
32. Cells were described for the first time by
_________.
33. The tiny organs of a cell are called
_________.
34. Fungi cannot make their own food because
they lack _________.
35. Mosses belong to the group called _________.
36. Invertebrates with spiny skins and hard
plates, are known as _________.
37. Birds possesses _________ bones.
38. The major distinguishing feature of
vertebrates in the presence of _________.
39. Mango is an Angiosperm plant with two
cotyledons. So it belongs to the subgroup called _________.
40. The internal factor necessary for
photosynthesis in plants is _________.
41. Glucose produced by photosynthesis may be
transformed into complex carbohydrates and other _________ which are utilized
by plants or stored in edible plant parts.
42. Plants, which feed on other plants and harm
them, are called _________.
43. Plants that feed on dead organic matter are
called _________.
44. Some plants are specially adapted to get
their food by _________ mode of nutrition.
45. Organic compounds in our food consisting of
carbon, hydrogen and oxygen are called _________.
46. Glucose and fructose combine to form a
2-sugar carbohydrate called _________.
47. One gram of glucose releases about _________
calories of energy.
48. The total number of known amino acids is _________.
49. All organisms need food for _________.
50. The building blocks of proteins are
_________.
51. Physical and chemical breakdown of food in
man first begins in the _________.
52. The blind sac at the juction of small and
large intestine is called _________.
53. Wave-like automatic contractions of the gut
are called _________.
54. The basic processes of transport of
substances in cells of all organisms are _________ and _________.
55. Plants transport water, minerals and food
from region to region by a _________ system.
56. Too rapid evaporation of water in hot
weather causes loss of _________ pressure in plant cells and _________ of
plants.
57. Leaves remain cool even in sunlight due to
the cooling effect of _________.
58. Heart failure may occur due to _________.
59. Hear muscle is different from _________ in
working continuously and automatically without experiencing fatigue.
60. A blockage in the _________ stops the flow
of blood and oxygen to muscles of the heart.
61. Respiration takes place in _________ cells
of a plant while photosynthesis occurs only in _________ parts.
62. During respiration _________ is released
from food.
63. Breathing means _________ of oxygen and
carbon dioxide with the _________.
64. Food is prevented from entering the larynx
by _________ which guards the opening into it.
65. Oxygen from the lungs is transported to the
cells in the form of _________.
66. The volume of the thoracic cavity increases
when muscles of the rib cage and the diaphragm _________.
67. The control center for breathing is located
in the _________.
68. The capillary network enclosed in Bowman’s
capsule is called _________.
69. Persons suffering from kidney failure can be
helped either by such artificial means as _________ or by _________
transplants.
70. Excretion involves removal of _________,
excess _________ and _________.
71. Nitrogenous wastes are produced when
_________ are metabolized.
72. Extra quantities of CO2, O2 and water in
plants is released through _________.
73. Like animals, plants too are _________ to
environmental factors.
74. Any environmental factor to which plants
react is called a _________ whereas the reaction itself is called a _________.
75. Support and movement human being is a
function of _________ and _________.
76. The body of invertebrates such as arthorpoda
is protected and supported by an _________.
77. The joints of skull bones are of _________
types.
78. Ligaments hold the _________ together.
79. The type of muscle which makes possible
movements of a vertebrate animal is called _________.
80. Co-ordination of various activities of the
body in multicellular animals is not possible without _________ systems.
81. Single-celled organisms are too small to
need special means of _________ of information.
82. Large animals have developed two special
systems of communication namely _________ and _________ systems.
83. The structure which perceive environmental
stimuli are called _________.
84. The main effectors in the body of animals
are _________ and _________.
85. Glands without duct are called _________.
86. Tissues and organs, which respond to
hormones, are called _________ sites.
87. The endocrine gland, which controls the
function of thyroid, adrenal, ovary and testis, is called _________ gland.
88. Hormones are substance made by _________ and
are released directly into _________.
89. Budding results in new individuals by the
process of _________ division.
90. The a***ual method of reproduction in yeast
is _________.
91. The 3rd and 4th whorls of flower are
_________ and _________.
92. Fusion of sperm with the egg results in
formation of a _________ with _________ number of chromosomes.
93. The part of the seed which contains
nourishment for the embryo is called _________.
94. The development of a tadpole to become an
adult frog is called _________.
95. The science which deals with the study of
viruses, bacteria, protozoa and microscopic fungi is called _________.
96. Some bacteria can reproduce so fast that
they can produce almost _________ generations in 24 hours.
97. Food can be preserved by _________,
_________ and _________.
98. Genetic engineering is a branch or area of
_________.
99. Biological principles which explain
similarities and differences among individuals are called _________.
100. The science which deals with structure and
working of DNA and genes inheritance is called _________.
101. Chromosomes consist of _________ and
_________.
102. An individual receives _________ percent of
its chromosomes from each parent during ***ual reproduction.
103. An ecologist specializes in learning about
interrelationships _________ and their interaction with _________ environment.
104. The components of environment are _________
and _________.
105. The place where organisms live is called
_________.
106. The different living thing component in an
ecosystem constitute a _________.
The basic functional unit of environment is an
_________.
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Correction
of Given Sentences
Friendsmania.net
Rewrite the following sentences after correcting
them:
1. Aristotle has been one of the most famous
Roman philosophers and naturalists.
2. A typical animal cell consists of cell wall,
cell membrane, nucleus and contains plastids, mitochondria, endoplasmic
reticulum, Golgi, ribosomes and centrosomes.
3. Ribosomes help in making fibres, which help
in movement of chromosomes during the cell division.
4. The hereditary material DNA is in the
endoplasmic reticulum.
5. Photosynthesis is an example of degradative
metabolism.
6. The typical number of chromosomes in a
resting cell is ‘n’ chromosomes.
7. In a cell which is ready for mitotic
division, the chromosomes and its DNA become half.
8. Penicillin is a bacterial product.
9. Ostrich is a bitd having very strong wing
muscles.
10. Leaves of monocotyledons possess veins in
the form of a network.
11. Proteins cannot be used by the body as a
source of energy.
12. Fatty substances in our food consist of fats
and vitamins.
13. One gram of fat produces less calories of
energy than is produced by the same amount of glucose.
14. An animal can grow and repair its damaged
tissues in the absence of protein in its food.
15. Proteins in our food are broken down into
amino acids during digestion so that we can make our own types of proteins.
16. The basic inorganic components in our food
are called Vitamins.
17. All plants make their food through process
of photosynthesis.
18. Photosynthesis occurs in two steps, the
first requires light but the second step requires more light than the first
step.
19. Photosynthesis is not affected by
temperature.
20. Symbiosis is an association between two
species in which neither the symbiont nor the host gets benefit.
21. Insectivorous plants, which are prevented
from trapping insects, die because they cannot make their own food.
22. Amylase is secreted by pancreas in the
duodenum for digestion of peptides.
23. Fats are emulsified by amylase.
24. Absorption of amino acids occurs in the
stomach.
25. HCl is produced in the stomach to prevent
peptic ulcers.
@import
"/extensions/GoogleAdSense/GoogleAdSense.css";
26. Final digestion of food by enzymes is
completed in the large intestine.
27. Bile and pancreatic enzymes enter the
stomach by bile and pancreatic ducts respectively.
28. Digestion in human beings is intracellular.
29. Solutes move in and out of cells along a
“down hill’’ concnetration gradient by osmosis.
30. A selectively permeable membrane allows
solutes to pass through freely but does not let water molecules to cross it.
31. A weak sugar solution has a lower osmotic
potential than a strong sugar solution.
32. Turgor pressure in plant cells develops due
to osmosis of water from the cell vacuole to the outside of the cell.
33. Lymph is plasma without antibodies.
34. Pulmonary veins bring deoxygenated blood to
the heart.
35. Oxygen liberated during photosynthesis by
the plants is used in only animal respiration.
36. The organelles responsible for
photosynthesis are the mitochondria in plant cells, and those of responsible
for respiration are chloroplasts.
37. The rings of cartilage in trachea prevent
entry of food into it.
38. The ciliated epithelium of the trachea can
be damaged by carbon dioxide.
39. The term “Respiration” can be defined merely
as the process of exchange of gases.
40. Nicotine deposits in cigarette smoke has
been shown to decrease the number of blood vessels in lungs.
41. The outer region of the human kidney is
medulla and the inner is cortex.
42. The filtrate is plasma containing everything
including blood cells and proteins.
43. The composition of urine of a person and the
amounts of substances in it cannot tell us whether the kidney function is
normal or abnormal.
44. Re-absorption of glucose from the filtrate
occurs in the lower coiled part of the tubule.
45. The Bowman’s capsule enclosing the
glomerulus as well as the coiled parts of the nephron lie in the medulla of the
kidney.
46. Those regions of a plant which receive
stimuli are called responsive regions, while those which react in particular
ways are called perceptive regions.
47. Plants exhibit sensitivity to environmental
factors by only secreting hormones.
48. Animals such as arthropods have both an
exoskeleton and endoskeleton but vertebrates have only exoskeleton.
49. All movements seen in an animal are
locomotory movements.
50. When a person bends his arm the action is
called extension.
51. Long bones of the body continue growing
until old age.
52. Receptors bring about actions according to
commands from the central nervous system.
53. Electric currents are generated in neurons
due to changes in the position.
54. An automatic and sudden response to
sensations is called a reflex arc.
55. The sensory cells of the retina, which
function in dim light, are the cones.
56. The organ of corti is located in the nasal
epithelium.
57. The endocrine system communicates messages
faster than the nervous system.
58. The pituitary gland produces two types of
hormones.
59. Disorders to endocrine system cannot be
corrected medically.
60. The endocrine glands respond to only
internal environmental stimuli.
61. Plumule develops into root (underground
part) of a seedling.
62. The type of germination which brings the
cotyledons out of the soil is known as hypogeal germination.
63. An individual will die if it does not
reproduce but a species can survive without reproduction.
64. The radicle of the embryo in a seed has
characters of both root and shoot.
65. The process by which an embryo is activated
to form a seedling is called vegetative propagation.
66. The first or primary root of a seedling is
formed by the hypocotyle.
67. Low temperature kills micro-organisms
whereas high temperature stops or slows their growth.
68. Dry heat of an oven is more effective in
killing micro-organims than moist heat.
69. All micro-organisms are harmful to human
beings, animals and plants.
70. Poliomyelitis is caused by a species of
bacterium called shigella whereas typhoid is caused by a virus.
71. Pateurization is a process in which food
such as milk is heated to different temperatures over a period of 24 hours.
72. The chromosomes, which are similar in size
and shape, are called mitotic chromosomes.
73. Alternative forms of a gene, which
determines a given character, exist on non-homologous chromosomes.
74. The gene which suppresses or masks
expression of its alternative form is called recessive.
75. Malaria and Cholera are heritable disease.
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Multiple
Choice Questions
From Guess Papers
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Choose the correct answers from the following:
1. _________ described the circulation of blood
in 13th century.
(Bu Ali Sina, Ali Bin Isa, Ibn-Al Nafees)
2. Each fore limb of frog has _________ fingers.
(4, 5, 6)
3. Fruit is formed by the enlargement of
_________.
(Stigma, Style, Ovary)
4. The earthworm belongs to the phylum
_________.
(Nematoda, Annelida, Mollusca)
5. The saliva contains an enzyme known as
_________, which acts on carbohydrates.
(Lipase, Trypsin, Ptyalin)
6. _________ tissues specialize in contraction.
(Connective, Muscle, Nervous)
7. Goitre is caused by the deficiency of
_________.
(Insulin, Glucagon, Iodine)
8. There are _________ chromosomes in each cell of
a human being.
(24, 32, 46)
9. “Al-Qanun Fi-Tibb” is written by _________.
(Al-Tabra, Al-Farabi, Bu Ali Sina)
10. _________ is the sensory layer of the eye.
(Sclerotic, Retina, Choroid)
11. Cockroach belongs to the phylum _________.
(Annelida, Arthropoda, Nematoda)
12. There are _________ toes in each foot of
frog.
(4, 3, 5)
13. Monotropa and Neottia exist as _________.
(Parasites, Saprophytes, Insectivores)
14. The movements in Rifolium and in the flowers
of Zafaran are _________.
(Nastic, Tropic, Tactic)
15. Diabetes is caused by the deficiency of
_________.
(Thiamine, Insulin, Iodine)
16. _________ are important in the synthesis of
proteins.
(Ribosomes, Centrosomes, Chloroplast, Lysosomes)
17. Stem increases in thickness due to _________.
(Cambium, Epidermis, Hypodermis, Endodermis)
18. The inner wall of the stomach secretes
_________ and hydrochloric acid.
(Ptyalin, Pepsin, Trypsin, Lipase)
19. Smut attacks _________.
(Leaves, Flowers, Fruits, Seeds)
20. The liver of frog is composed of _________
lobe/lobes.
(1, 2, 3, 4)
21. The organs meant to receive the information
are called _________.
(Sensory neutrons, Effectors, Receptors, Motor
Nerves)
22. Sea anemone belongs to the phylum _________.
(Protozoa, Coelenterata, Porifera,
Platyhelminthes)
23. Al-Nabatiat was written by _________.
(Ali Bin Isa, Abu Hanifa, Al-Daturi)
24. The fourth whorl of a flower is known as
_________.
(Corolla, Gynoecium, Calyx, Androecium)
25. _________ are flesh eaters.
(Omnivorous, Herbivorous, Carnivorous,
Parasites)
@import
"/extensions/GoogleAdSense/GoogleAdSense.css";
26. A group of cells with similar structure and
function is called _________.
(Organism, Organ, Organelle, Tissue, none of the
above)
27. _________ of the following groups of
organisms lack nucleus.
(Cocci, Mosses, Diatoms, Fungi, Euglena)
28. Ferns belong to the group _________.
(Bryophytes, Algae, Pteridophytes, Gymnosperms,
Angiosperms)
29. The body wall consists only two layers of
cells in _________.
(Flatworms, Coelenterates, Sponges, Ascaris,
Tapeworm)
30. Joined limbs are present in _________.
(Octopus, Hookworms, Hydra, Spiders, Star
fishes)
31. _________ and _________ contains combination
of plants which produce seeds.
(Hibiscus and Algae, Mosses and Ferns, Mosses
and Conifers, Fungi and Conifers, Conifers and hibiscus)
32. _________ groups are said to form “base of
food chain’’ because of their photosynthetic ability.
(Bacilli, Bryophytes, Fungi, Algae, Poriferans)
33. The tissue of green leaf where major
photosynthesis occurs is _________.
(Mesophyll, Epidermis, Phloem, Xylem)
34. _________ is a rich source of Carbohydrate.
(Milk, Fish fingers, Potato chips, Boiled egg,
Roast beef)
35. The last source of chemical energy in a
starved person deprived of food is _________.
(Muscles of his body, body fat, Carbohydrates,
Vitamins and minerals, Bones)
36. _________ storage material in plants is most
readily utilized for release of energy.
(Carbohydrate, Protein, Fat, Oil)
37. _________ and _________ are the products
that are formed when yeast cells respire anaerobically.
(Glucose and Oxygen, Carbon dioxide and Alcohol,
Lactic Acid and Water, Carbon dioxide and Water, Glucose and Oxygen)
38. _________ is the region where gases are
exchanged in humans.
(Trachea, Bronchioles, Alveoli, Bronchi, All of
the above)
39. The breathing rate in humans is controlled
by _________.
(Oxygen in blood, Relaxation of rib muscles,
Haemoglobin in R.B.C, Carbon dioxide in blood, Epiglottis)
40. The fluid in the collecting duct of nephron
enters first into _________.
(Bowman’s capsule, Pelvis, Urinary Bladder,
Ureters, Urethra)
41. In humans, re-absorption of most of the
water and amino acids from the blood filtrate is done in the _________.
(Glomerulus, u-shaped loop of nephron, Pelvis,
Lower coiled tube, Upper coiled tubule)
42. The fluid which flows down from the Bowman’s
capsule is _________.
(Urine, Filtrate, Water containing proteins,
none of above)
43. The nephrone makes urine by _________.
(Filtration mechanism, Pricipitation Mechanism,
Re-absorption mechanism, filtration and precipitation mechanism, Filtation and
Re- absorption mechanism)
44. The movement of some plants from the bottom
of a pond to the water surface toward light is called _________.
(Phototropism, Geotropism, Phototactic Response,
none of above)
45. Flowers of some plants open and close at
particular time of the day in response to light. Such as movement is an example
of _________.
(Phototropism, Phototactic Response, Geotropism,
Nastic Response)
46. Movements which are governed by the
direction of the stimulus are _________.
(Nastic, Tropic, Tactic, Nastic and Tropic,
Tropic and tactic)
47. The smallest structural unit of a muscle is
_________.
(A muscle fibre, a bundle of muscle fibres,
tendon, a muscle together with its nerve fibres)
48. The part of human brain which controls all
part of the central nervous system (CNS) and the body is _________.
(Midbrain, Cerebellum, Medulla, Cerebrum, Spinal
cord)
49. In humans, steroid hormones are made in and
secreted by _________.
(Thyroid and parathyroid, Pancreas and
pituitary, adrenals and gonads, all of the above, none of the above)
50. The process by which sperm in the male
enters the egg is called _________.
(Pollination, Maturation, Fertilization,
Germination, Meiosis)
51. _________ and _________ are the non
reproductive parts of a flower.
(Anther and syle, Ovule and sepal, Sepal and
Petal, Sitgma and Filament)
52. The part of seed, which arises from the
zygote, is _________.
(Endosperm, Seed Coat, Embryo, Micropyle)
53. Fruit is formed by enlargement of _________.
(Ovule of flower, Pedicel of flower, embryo in
the ovule, entire ovary containing the seed)
54. When certain foods are heated to 148.9°C to
kill all micro-organisms in 1-2 seconds the process is called _________.
(Boiling, pasteurization, sterilization,
steaming under pressure)
55. The body of patient looses water and salts
in faeces which may appear like rice water in patients suffering from
_________.
(Typhoid, Tetanus, Bacillary dysentry, Cholera)
56. _________ diseases are most likely to occur
due to contaminated water and food.
(Poliomyelitis, Typhoid, Bacillary dysentry, all
of the above)
57. _________ diseases is caused by a protozoa.
(Malaria, Tetnus, Poliom, Tuberculosis)
58. If we could count all plants and animals in
a small ecosystem _________ will be the largest in number.
(birds, caterpillars, plants, insects)
59. If we were to represent organisms by number,
weight and size at various trophic level in the food chain, _________ will form
an inverted pyramid.
(number, size, weight, none of the above)
60. In an ecosystem several types of organisms
live as a community and _________ represents the secondary consumer.
(Earthworms, Fruit eating birds, Falcons and
eagles, rabbits, mice)
61. The following organism occupy different
trophic levels in food chain, _________ receives the least share of sun’s
energy.
(Cow, Algae, Rose Plant, Caterpillar, Man)
62. _________ is not a consequence of deforestation.
(Green house effect, Depletion of Ozone layer,
Soil Erosion, Disturbed Water cycle, Disturbed oxygen and Carbon dixoide cycle)
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Fill in the Blanks
Friendsmania.net
Complete the following sentences with
appropriate answers:
1. Cell was discovered in 1665 by _________.
2. Fungi cannot make their own food because they
lack _________.
3. The physical and chemical breakdown of food
in humans first begins in the _________.
4. During respiration _________ is released from
food.
5. The different parts of human body and their
functions are described in the book _________ written by Abdul Malik Asmai.
6. The study of tissues is called _________.
7. The hormone insulin is secreted by _________.
8. Tape-worm belongs to the phylum _________.
9. The fourth whorl of a flower is known as
_________.
10. Stem increases in thickness due to
_________.
11. The distance between two nodes of a stem is
called _________.
12. “Al-Mansoora” is written by _________.
13. The third eyelid (transparent membrane) that
protects the eye of frog in water is known as _________.
14. The organs of locomotion in _________ are
called Setae.
15. _________ supplies blood to the brain and to
the parts associated with the brain of forg.
16. The genes representing a pair of contrasting
characters are called _________.
17. Firdous-ul-Hikma is written by _________.
18. Star-fish belogns to the phylum _________.
19. Androecium is the _________ whorl of a flower.
20. Goitre is caused by the deficiency of
_________.
21. Fish respires by means of special structures
called _________.
22. _________ controls all functions of a cell.
23. A long narrow and cylindrical fruit of
Brassica compestris is called _________.
24. The transfer of pollen grains from another
to the stigma of carpel is called _________.
25. Excretory organs in insects are called
_________.
26. The single major contribution of Muslim
scientists in the field of scientific method is use of _________.
27. The two main subdivisions of biology are
_________ and _________ each of which has several further branches.
28. Life can be best defined by comparing
_________ of living things with those of _________ things.
29. When food is burnt in our cells in the
presence of oxygen to produce energy the process is called _________.
30. When a cell divides to produce two new cells
exactly like the parent the process is called _________.
31. The sum of chemical reaction in cells is
called _________.
32. Cells were described for the first time by
_________.
33. The tiny organs of a cell are called
_________.
34. Fungi cannot make their own food because
they lack _________.
35. Mosses belong to the group called _________.
36. Invertebrates with spiny skins and hard
plates, are known as _________.
37. Birds possesses _________ bones.
38. The major distinguishing feature of
vertebrates in the presence of _________.
39. Mango is an Angiosperm plant with two
cotyledons. So it belongs to the subgroup called _________.
40. The internal factor necessary for
photosynthesis in plants is _________.
41. Glucose produced by photosynthesis may be
transformed into complex carbohydrates and other _________ which are utilized
by plants or stored in edible plant parts.
42. Plants, which feed on other plants and harm
them, are called _________.
43. Plants that feed on dead organic matter are
called _________.
44. Some plants are specially adapted to get
their food by _________ mode of nutrition.
45. Organic compounds in our food consisting of
carbon, hydrogen and oxygen are called _________.
46. Glucose and fructose combine to form a
2-sugar carbohydrate called _________.
47. One gram of glucose releases about _________
calories of energy.
48. The total number of known amino acids is
_________.
49. All organisms need food for _________.
50. The building blocks of proteins are
_________.
51. Physical and chemical breakdown of food in
man first begins in the _________.
52. The blind sac at the juction of small and
large intestine is called _________.
53. Wave-like automatic contractions of the gut
are called _________.
54. The basic processes of transport of
substances in cells of all organisms are _________ and _________.
55. Plants transport water, minerals and food
from region to region by a _________ system.
56. Too rapid evaporation of water in hot
weather causes loss of _________ pressure in plant cells and _________ of
plants.
57. Leaves remain cool even in sunlight due to
the cooling effect of _________.
58. Heart failure may occur due to _________.
59. Hear muscle is different from _________ in
working continuously and automatically without experiencing fatigue.
60. A blockage in the _________ stops the flow
of blood and oxygen to muscles of the heart.
61. Respiration takes place in _________ cells
of a plant while photosynthesis occurs only in _________ parts.
62. During respiration _________ is released
from food.
63. Breathing means _________ of oxygen and
carbon dioxide with the _________.
64. Food is prevented from entering the larynx
by _________ which guards the opening into it.
65. Oxygen from the lungs is transported to the
cells in the form of _________.
66. The volume of the thoracic cavity increases
when muscles of the rib cage and the diaphragm _________.
67. The control center for breathing is located
in the _________.
68. The capillary network enclosed in Bowman’s
capsule is called _________.
69. Persons suffering from kidney failure can be
helped either by such artificial means as _________ or by _________
transplants.
70. Excretion involves removal of _________,
excess _________ and _________.
71. Nitrogenous wastes are produced when
_________ are metabolized.
72. Extra quantities of CO2, O2 and water in
plants is released through _________.
73. Like animals, plants too are _________ to
environmental factors.
74. Any environmental factor to which plants
react is called a _________ whereas the reaction itself is called a _________.
75. Support and movement human being is a
function of _________ and _________.
76. The body of invertebrates such as arthorpoda
is protected and supported by an _________.
77. The joints of skull bones are of _________
types.
78. Ligaments hold the _________ together.
79. The type of muscle which makes possible
movements of a vertebrate animal is called _________.
80. Co-ordination of various activities of the
body in multicellular animals is not possible without _________ systems.
81. Single-celled organisms are too small to
need special means of _________ of information.
82. Large animals have developed two special
systems of communication namely _________ and _________ systems.
83. The structure which perceive environmental
stimuli are called _________.
84. The main effectors in the body of animals
are _________ and _________.
85. Glands without duct are called _________.
86. Tissues and organs, which respond to
hormones, are called _________ sites.
87. The endocrine gland, which controls the
function of thyroid, adrenal, ovary and testis, is called _________ gland.
88. Hormones are substance made by _________ and
are released directly into _________.
89. Budding results in new individuals by the
process of _________ division.
90. The asexual method of reproduction in yeast
is _________.
91. The 3rd and 4th whorls of flower are
_________ and _________.
92. Fusion of sperm with the egg results in
formation of a _________ with _________ number of chromosomes.
93. The part of the seed which contains
nourishment for the embryo is called _________.
94. The development of a tadpole to become an
adult frog is called _________.
95. The science which deals with the study of
viruses, bacteria, protozoa and microscopic fungi is called _________.
96. Some bacteria can reproduce so fast that
they can produce almost _________ generations in 24 hours.
97. Food can be preserved by _________,
_________ and _________.
98. Genetic engineering is a branch or area of
_________.
99. Biological principles which explain
similarities and differences among individuals are called _________.
100. The science which deals with structure and
working of DNA and genes inheritance is called _________.
101. Chromosomes consist of _________ and
_________.
102. An individual receives _________ percent of
its chromosomes from each parent during sexual reproduction.
103. An ecologist specializes in learning about
interrelationships _________ and their interaction with _________ environment.
104. The components of environment are _________
and _________.
105. The place where organisms live is called
_________.
106. The different living thing component in an
ecosystem constitute a _________.
107. The basic functional unit of environment is
an _________.
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Frog
Friendsmania.net
Frog is found in he water or near the water. It
belongs to class Amphibia. it passes a specific part of life in water and
remaining life on land. Its bilogical name is Rana Tigrina. It is a cold
blooded animal i.e. blood temperature changes with that of the environment. At
the start of winter, water is decreased and temperature is lowered, the frog
lives buried in the mud to over come winter.
(Figure)
Coelom
The body cavity of frog is called Coelom. It
contains many organs which form different systems.
Digestive System of Frog
This system consists of alimentary canal and
accessory glands like liver and Pancreas.
Alimentary Canal
It is a coiled tube through which food passes.
It consists of buccal cavity, pharynx, oesophagus, stomach and intestines.
Buccal Cavity and Pharynx
Mouth is present between upper and lower jaws.
Upper jaw has a row of pointed maxillary teeth. Lower jaw lacks teeth. There is
a pair of set of vomerine teeth on the roof of the buccal cavity. Frog does not
chew the food with teeth. But teeth are used only to grasp the food. The old
teeth are continuously replaced by the new teeth through its life. Near the
vomerine teeth, internal nostrils are present on the roof of the buccal cavity.
These open outwards into external nostrils. Behind them, two large bulges
indicate the position of eyes. The tongue of frog is sticky. The tongue is
attached at anterior end of buccal cavity. The posterior end of tongue is free
and bifid. the frog feeds on different insects. To capture its prey, it
suddenly throws its tongue on to the prey, which sticks to the tongue and is
brought to the buccal cavity, when the tongue is drawn back.
Near the maxillary joints, pair of opening of
eustachian tubes are present. In male frog, there is also, present a pair of
opening of vocal, sacs on the lateral side of floor of the buccal cavity which
help the croaking. Buccal cavity narrows, posteriorly to form pharynx. The
digestive system, respiratory system and ears are linked to pharynx. In
posterior part of pharynx, there is another opening called Glottis. This leads
to lungs through tachea. It closes at the time of digestion of food but remains
open when animal is respiring.
(Diagram)
Oesophagus, Stomach and Intestine
Pharynx leads into a small but wider tube called
oesophagus or gullet. The oesophagus opens into the stomach. The anterior end
of stomach is called Cardiac end while the posterior end is called Pyloric end.
The walls of stomach are muscular and glandular.
The muscles of walls of stomach contract and
relax, by which food is broken down into tiny pieces. The secretions of stomach
have different enzymes which help in chemical digestion. In stomach, digestion
of protein of food is started. After stomach, first part of intestine begins
which is called duodenum. The ducts from liver and pancreas open into the
duodenum. These ducts bring juices from these glands. The second part of
intestine is Ilium are called Small intestine. The secretion of pancreas is
called Pancreatic Juice. Pancreatic juice enters the bile duct by small duct.
This juice digests the food and brings in such form which can be absorbed by
the blood through intestine. Digested food is absorbed by illium and surplus
water is absorbed by recturm. Remaining undigested food is expelled though
cloacal aperture. A membrane keeps the intestine intact at a place and prevents
strangulation of small intestine. This membrane is called mesentery.
Respiroatory System of Frog
There are three methods of respiration in frog.
- Pulmonary Respiration
- Cutaneous respiration
- Buccal Respiration
(Diagram)
Pulmonary Respiration
The exchange of gases through lungs is called
pulmonary respiration. In this process, frog keeps its mouth closed. Air
reaches buccal cavity through nostrils. Nostrils are closed floor of buccal
cavity is raised; glottis opens, and air is pushed into the lungs. The intake
of air is called inspiration. In frog, there is a pair of balloon shaped lungs.
Each lung consists of small thin walled chambers called alveoli which greatly
increase the surface area of the lungs. On each alveolus, there are many blood
capillaries. When lungs are filled with air, then exchange of gases occurs
between blood and air in lungs at the site of alveoli. During this, the exchange
of gases occurs between blood and air present in buccal cavity. After this air
is removed from the lungs. Frog uses its nostrils and floor of buccal cavity
for inspiration and expiration.
Oxygen present in the air is dissolved in
moisture present on lining of lungs. Then oxygen is diffused into the blood
where it combines with hemoglobin to form oxyhaemoglobin. This oxygenated blood
goes to all parts of the body by means of capillaries. Where oxygen separates
from oxyhaemoglobin molecules and is absorbed by the cells. Carbon dioxide from
cells comes out into the blood, which carries it to the lungs, and from here
carbon dioxide is expelled.
Cutaneous Respiration
In frog, exchange of gases occurs through skin
during hibernation and swimming. This is called cutaneous respiration. Skin is
richly supplied with capillaries. Skin is moist. Oxygen diffuses through skin
to capillaries and is carried by blood and CO2 diffuses back to blood from
cells and is discharged out.
Circulatory System of Frog
It consists of blood vascular and lymphatic
systems.
Blood Vascular System
The blood vascular system of frog consists of
following parts:
- Heart
- Arteries
- Veins
- Capillaries
Structure of Heart
Heart is conical organ. It is muscular. It has
three chambers. It is present in the body cavity between the oesophagus and
sternum. Like a pump, it contracts and is relaxes. As a result of this, blood
continuously circulates in the body. The heart is surrounded by a membrane
which is called pericardial which protects the heart.
(Figure)
The three chambers of heart are as follows:
1. Right Atrium
2. Left Atrium
3. Ventricle
the two atria form the broader interior part of
the heart. The right atrium is larger than left atrium. Both atria are thin
walled. The posterior conical thick walled part of the heart is called
ventricle. A broad vessel, which is called truncus artenosus, arises from
dorsal side of the ventricle and then divides into two branches near the atria.
A thin walled triangular sinus venosus opens into the right atrium. Some
biologists consider truncus arteriosus and sinus venosus as chambers of the
heart.
Function of Heart
- The chambers of the heart beat in a rhythmic way.
- First of all sinus venosus contracts. Then, the two
atria contract. After this ventricle and finally truncus arteriosus is
contracted.
- The deoxygenated blood from the whole body except lungs
is carried to sinus venosus by two precavals and one post caval.
- Sinus, venosus opens into the right atrium through an
opening.
- Oxygenated blood from the lungs is brought into the the
left atrium by two pulmonary veins.
- Both the atria open into the ventricle and push their
blood collectively into the ventricle by a common aperture, which is
guarded by a valve.
- This valve maintains the unidirectional flow of blood
in the heart and prevents the back flow of blood.
- In the middle of ventricle some mixing of oxygenated
and deoxygenated blood takes place. On the two sides the blood remains
unmixed due to rapid flow of blood.
- When ventricle contracts the blood goes to the truncus
arteriosus through an aperture. This aperture controls the speed and
direction of the blood by a spiral valve present at the start of truncus
arteriosus.
Arterial System of Frog
The blood vessels which carry the blood from
heart to different parts of the body are called arteries. The system consisting
of arteries is called arterial system.
(Diagram)
It starts from truncus arteriosus. It is divided
into two main branches each of which further divides to form three small
branches.
Carotid Arch
It supplies blood to lower jaw, tongue, eye and
brain.
Pulmocutaneous Arch
It carries blood to lungs and skin.
Systemic Arch
Right and left systemic arches joint posteriorly
to form dorsal aorta. But prior to their union, each systemic arch gives out
arteries supplying blood to vertebral column, oesophagus and fore limbs.
Dorsal Aorta
It runs along the vertebral column towards hind
limbs. It gives off following branches.
Coeliacomesenteric Artery
It supplies blood to digestive system.
Renal Arteries
These supply blood to kidneys and general
organs.
Posterior Mesenteric Artery
It supplies blood to rectum.
Illiac Arteries
These supply blood to hind limbs of their sides.
After reaching their specific organs, all the
arteries divide and redivide to form capillaries. The walls of capillaries are
very thin. Due to this reason, the exchange of materials take place between
blood and tissues. The capillaries join to form venules. These venules join to
form veins. Then these veins carry blood back to heart.
Venous System
The blood vessels which bring the blood from
different body parts, back into the heart are called veins. The system
containing of veins is called Venous system.
Following are the major veins in frog.
Pulmonary Veins
Blood from right and left lungs goes to left
atrium through pair of pulmonary veins. These have oxygenated blood.
Right and Left Precavals
Each precaval is formed by union of three veins
which bring blood from tongue, lower jaw, head, shoulders, forelimbs and skin.
Both veins open in sinus venosus. From here blood goes to right atrium.
Postcaval
It is formed by union of five or six pairs of
renal veins from the kidney and the genital veins. While passing through the
liver, it receives two hepatic veins. Then it enters the sinus venosus.
Therefore, venous blood from different body parts enters the heart.
Renal Portal Vein
The veins which bring blood from the hind limbs
and pelvic region combine to form Renal portal vein. The renal portal vein
enters the kidney of its side and form capillaries. Blood from kidney goes to
the post caval through renal veins. Post caval caries the blood to the heart.
Abdominal Vein
The Pelvic veins of two sides combine to form
abdominal vein. Before entering the liver, it divides into branches. In liver,
it is further divided to form capillaries. The blood from the liver is drained
into post caval by hapatic veins of both sides.
Hepatic Portal Vein
The blood vessels (veins) bringing blood form
various organs of digestive system (stomach, duodenum, illiums, rectum,
pancreas and spleen etc) combine to form a large vein. This is known as hepatic
portal vein. Near the liver a branch of abdominal vein combines with it. Then
it enters the liver and divides and redivides to form capillaries. The, blood
entering the liver through hepatic portal veins goes to the post caval by means
of hepatic veins. The blood from post caval goes to heart through sinus
venosus.
The blood coming back into the heart is of two
types.
- Oxygenated blood which comes from lungs by pulmonary
veins.
- Deoxygenated blood from all parts of the body enters
sinus venosus through precavals and post caval and then enters the right
atrium.
(Diagram)
Lymphatic System of Frog
In circulatory system, due to blood pressure,
many components of blood plasma come out of the capillaries and fill the inter
cellular spaces. These components are also in the form of fluid and called
tissue fluid or interstitial fluid. Much of it reenters the capillaries and
some of it enters the lymph vessels where it is known as lymph. The flow of
lymph is unindirectional. Through lymph "vessels" lymph goes to big
veins. Thus, lymph again enters the blood.
1. The lymph keeps the tissues wet.
2. The lymph helps in transport of various
substances from blood to tissues and vice versa.
Excretory System of Frog
In frog, waste materials are removed in
different ways e.g. through skin, lungs, liver digestive system etc. But for
removal of nitrogenous wastes, there are two kidneys. Kidneys are attached to
dorsal wall of body cavity. These are present close to vertebral column in
posterior part of body cavity. These are elongated and made up of urinary
tubules. Urinary tubules combine to form collecting ducts which open into
Ureter. The urine from kidneys comes into ureters after illustration. Both
ureters which start from edges of kidneys open into the cloaca. From here,
urine is excreted directly or stored in the urinary bladder, which on opening
of cloacal aperture is expelled. The carbon dioxide and water are excreted
through lungs and skin while through liver and digestive system; undigested
food and some wastes are excreted.
(Diagram)
Reproductive System of Male Frog
The reproductive system of male frog consists of
a pair of testes and reproductive ducts. Each testis is attached to kidney by
means of a membrane. At anterior end of testis, there is present fat body. Each
testis is composed of small ducts called seminiferous tubules in which sperms
are produced. Sperms enter the kidney via vesa efferentia. Sperms reach the
cloaca through ureter. From here, these are dischaged in the water through
cloacal aperture in this way, ureter in male frog does two jobs, one is removal
of urine and other is removal of sexual material, so it is called urinogenital
duct and the urinary system and genital system are collectively call
urinogenital system.
Reproductive System of Female Frog
The reproductive system of female frog consists
of a pair of ovaries and reproductive ducts. Ovaries are present close to the
kidneys. At their anterior ends, there are present fat bodies. Each ovary
contains many follicles in which eggs (ova) are produced. During breeding
season, ovaries are enlarged. Ova are released into the body cavity through the
coelomic fluid, these enter the oviduct. The anterior part of oviduct is funnel
like called oviducal funnel and reach the uterus. The uterus opens into the
cloaca. At last, ova are discharge in the water through cloacal aperture. In
water, union of sperm with egg results in formation of zygote. From zygotes,
offsprings are formed and in this way continuity of race is ensured.
Nervous System of Frog
It consists of three parts:
1. Central Nervous System
2. Peripheral Nervous System
3. Sympathetic Nervous System
Central Nervous System
It consists of brain and spinal cord.
(Diagram)
Brain
Brain is enclosed in protective layers and is
located in cranium or brain case, which is major part of skull.
(Diagram)
Brain is divided into three parts:
(a) Fore Brain
(b) Mid Brain
(C) Hind Brain
(a) Fore Brain
This is anterior part of brain. This is
associated with sense of smell. It controls the secretion of many hormones. It
also receives messages from internal and external environment of the body.
(b) Mid Brain
This is central part of brain. This is
associated with eyes and vision.
(c) Hind Brain
This is the posterior part of brain. It controls
and coordinates body movements and maintains balance of the body. It also
controls respiration, circulation, taste and digestion.
Spinal Cord
The posterior part of the brain is continuous
with spinal cord. It runs through the vertebral column. The spinal cord
controls the movements of trunk region.
Peripheral Nervous System
It consists of nerves. These nerves connect the central
nervous system (CNS) with various parts of the body. Some nerves originate from
brain. These are called cranial nerves other nerves originate from spinal cord.
These are called spinal nerves. In frog, there are 10 pairs of cranial nerves
and 9 or 10 pairs of spinal nerves.
Cranial
Basically, nerves are of three types:
Sensory Nerves
These take messages from sensory organs to CNS.
Motor Nerves
These take messages from CNS to glands and
muscles.
Mixed Nerves
These do both above mentioned functions.
Cranial Nerves
In these nerves, first, second and eight pairs
are sensory nerves which are associated with senses of smell, sight and
hearing. Third, fourth and sixth pairs are motor nerves which carry message
from brain to the eye. Nine and ten pairs are mixed nerves, which are supplied
to jaw, face, tongue and heart.
Spinal Nerves
These are all mixed nerves. These control
functions of different organs.
Ear of Frog
The organ of hearing in frog is "Ear"
like other vertebrates.
Structure of Ear of Frog
The ear of frog consists of following three
parts.
1. External Ear
2. Middle Ear
3. Internal Ear
External Ear
External ear consists of a bone. The vibration
is produced in external ear when sound waves strike with it.
(Figure)
Middle Ear
Middle Ear consists of a tympanic membrane. On
the inner side of the membrane is a cavity known as tympanic cavity. The cavity
contains small rod like bones called ossicles. The middle ear is connected to
internal ear by a tube which is called Eustachian tube; it transfers the
vibrations towards the internal ear.
Internal Ear
The internal ear is a very delicate organ. It
consist of three semi circular canals. These canals are filled with a fluid and
sensory cells are located at special places in these canals.
Function of Ear of Frog
When sound waves strike the tympanic membrane,
it is set into vibration, this is in turn vibrates the internal ear and thus
sound waves stimulate the hearing receptors in the inner ear. The internal ear,
in addition to hearing also keeps the balance of the body.
Eye of Frog
The frog has two eyes one on each side of the
head. If we make vertical section of the eye, we find that the innermost layer
of the ball is the sensory retina. The retina contains photoreceptor cells. Outside
the retina is the choroid, which is richly supplied with blood capillaries
supplying nutrients to the retina. The sclerotic is the hard, outer most layer
of the eye. It provides shape to the eye ball. The anterior transparent part of
the eye is called cornea. Behind the cornea is Iris. The Iris has a window
called the pupil. Behind the pupil is the lens of the eye. The cornea, pupil
and lens focus light on the retina. A watery fluid is present in between the
cornea and lens. Similarly a jelly like fluid is present between the lens and
retina, through which light passes before it strikes retina. Optic nerve takes
the sensory messages from the eye to the brain.
(Diagram)
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Multicellular
Organism (Brassica Plant)
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Multicellular Organism
The organisms consisting of many cells are
called multicellular organism. e.g. Brassica Plant, frog, man etc. diagram?
Brassica Plant (Mustard Plant)
1. This plant is sown in winter and at the end
of season, it produces seeds and then dies.
2. This is an annual plant.
3. An oil is extracted from seeds of this plant
which is known as mustard oil.
5. The scientific name of this plant is Brassica
Campestris.
(Diagram)
Non-Reproductive Parts or Vegetative Parts
These parts do not directly take part in sexual
reproduction e.g. root, stem, branches and leaves.
Reproductive Parts
These parts directly take part in sexual
reproduction e.g. flower, fruit and seed.
Root of Brassica
The root is that part plant which is present
inside the soil. It is produced from radical of seed. The first formed root is
called Primary root. During its growth, it gives off secondary and tertiary
root. Each root has a root cap at its tip or apex. Behind the root cap, root
hairs are present which absorbs water and salts from the soil. Roots also
anchor the plant firmly in the soil.
(Diagram)
Internal Structure of Root of Brassica
When transverse section of root of Brassica is
observed under the microscope, the following parts are very prominent.
Epidermis
It is outermost and protective layer. It is
single celled. Some cells grow outward to form root hair.
Cortex
It is present inner to epidermis. It is made up
of several layers of thin walled living cells (parenchyma cells). There are
present intercellular spaces. These cells store food.
Endodermis
it is the innermost layer of cortex. There are
no intercellular spaces. There are thickenings of special materials around the
cell which check diffusion of water from xylem to cortex.
Pericycle
The layer present inner to endodermis is called
pericycle. There are also no intercellular spaces. All the branches of roots
arise from pericycle.
Vascular Bundles
Xylem is present in middle of root which extends
to pericycle in the form of four rays and controls one way transport of water
and salts. In between the xylem rays, phloem bundles are present which
transport food in two directions.
Stem of Brassica
The stem is that part of the plant which grows
above ground. It arises from plumule of seed. It is herbaceous and branched. It
bears leaves and flowers. The part of stem or its branch from where a leaf
arises is called node. The part between two nodes is called internode. the
important function of stem is the conduction of prepared food from leaves to
other parts and that of water absorbed from roots to leaves. It supports
leaves, flowers and fruits like a pillar. It keeps the leaves in such a
position that they can get light to prepare food.
(Diagram)
Internal Structure of Stem of Brassica
When transverse section of stem of Brassica is
observed under the microscope, following parts are visible.
Epidermis
It is the outermost protective layer of stem.
Outer to epidermis, there is layer of cutin which reduces loss of water from
stem. The cells are compactly arranged and there are no intercellular spaces.
Cortex
It is inner to epidermis. It is made up of many
layers of parenchyma and collenchyma tissues. The main function of cortex is
storage of water and food.
Endodermis
It is innermost layer of cortex. It is not
prominent in stem. It allows suitable quantity of waer to enter cortex from
xylem.
Pericycle
It is in the form of bundles in between the
endodermis and vascular bundles. It is composed of sclerenchyma cells. It forms
bundle cap.
Vascular Bundles
In stem, vascular bundles are arranged in the
form of ring. Vascular bundle consists of phloem and xylem. Phloem is towards
outside and xylem is towards inside. Few layers of cambium are present between
the xylem and phloem. Cambium causes increase in diameter of the stem with
passage of time.
Medullary Rays
There are present few layers of thin walled
living cells between every two layers. These are called medullary rays. The
medullary rays connect the cortex with pith for the transport of food.
Pith
The central part of stem consists of living,
rounded, thin walled parenchyma cells. This part is called pith. Here food is
stored.
Leaf of Brassica
1. Leaf is produced on node of stem or its
branch.
2. Each leaf consists of two parts. The stalk of
leaf is called petiole and upper broad part is called lamina.
3. Young leaves are without petiole and their
margins are entire or smooth.
4. Lower leaves are large in size. These are
also without petiole but there margins are wavy.
5. In the middle of leaf there is a thick
midrib.
6. From midrib, arise veins of different
thickness and form a network in leaf. This arrangement of veins is called
reticulate venation.
7. Veins are composed of xylem and phloem.
8. The angle formed between stem and leaf is
called axil. In this axil, buds are present which gwo and become branches.
9. The dorsal and ventral surfaces of leaves are
different from each other. Such leaves are called bifacial leaves.
10. The main function of leaf is the preparation
of food by process of photosynthesis.
Internal Structure of Leaf
When transverse section of leaf is observed
under the microscope, following structure are visible.
(Diagram)
Epidermis
This layer of cells covers both upper and lower
surfaces of leaf. Upper layer is called upper epidermis and lower layer is
called lower epidermis. There are more number of stomata in lower epidermis
than upper epidermis. This results in less transpiration and CO2 enters
according to need. Each stomata consists of two guard cells, which are bean
shaped, or kidney shaped. There is a pore between guard cells through which
exchange of gases takes place and water vapours come out of leaves.
Mesophyll
The tissue present between upper and lower
epidermis is called mesophyll. It consists of two parts.
Palisade Mesophyll
Uper part consists of elongated cells which hare
lying vertical. These are double layered closely packed cells and are called
Palisade Mesophyll.
Spongy Mesophyll
The lower part is sponge like and has more
intercellular spaces. This is called spongy mesophyll.
Both types of cells have chloroplasts containing
chlorophyll. So, photosynthesis takes place here. The function of mesophyll is
to manufacture food for the plant.
Vascular Tissue
It consists of midrib and veins. The midrib is
bundle. Upper part of midrib is xylem and lower part is phloem. Pericycle and
endodermis surround this bundle. Besides this Lamina has other bundle which are
called veins.
Flower of Brassica
The flower is reproductive part. With the
maturation of age, the plant bears yellowish flowers. Many flowers are arranged
on a branch in a special way. This branch is called peduncle. This arrangement
of flowers on the peduncle is called Inflorescence.
Parts of Flowers
Flower consists of a stalk and floral leaves.
The stalk is called Pedicel. The upper part of pedicel is comparatively swollen
and flattened. This is called thalamus. On the thalamus, floral leaves are
arranged in four whorls.
(Diagram)
The details of floral leaves is as follows:
Calyx
It is the outermost whorl of floral leaves. It
consists of four sepals. On maturation, its colour changes to yellow. In young
flowers sepals cover the inner parts of the flower. The main function of calyx
is to protect inner parts of the flower.
Corolla
It is the second whorl of floral leaves. It
consists of four free petals. Its yellow colour is conspicuous and can attract
insects, honey bees and butterflies which help in pollination.
Androecium
It is the third whorl present inner to petals.
It is the male reproductive part. It consists of six free stamens. These are
arranged in two whorls, the outer whorl has two small stamens and inner whorl
has four long stamens. Each stamen consists of two parts. Lower stalk is called
filament. Upper swollen part is called anther, Inside anther, a large number of
pollen grains are produced. When anther matures, a longitudinal slit appears in
its walls from which pollen grains escape. AT the base of filament, four
nectaries are present. These nectaries secrete nectar. To get nectar, insects
visit the flowers. In this way, pollen grains get attached to the bodies of
insects and are transferred from one flower to the other. This process is
called pollination.
Gynoecium
It is the inner most part of flower. It is
female reproductive part. It consists of two carpels, which are fused. Each
carpel has three parts. The basal swollen part is called ovary. The stalk like
part above the ovary is called Style. The top of style is somewhat swollen and
it is called Stigma. Overy contains many ovules. Ovules are ripened to form
seeds while ovary is ripened to form fruit. The fruit of Brassica is called
Siliqua
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Unicellular
Organism (Amoeba)
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IX Biology - Chapter 2 - Unicellular Organism
(Amoeba) From AwamiMarkaz.com Wiki Notes Jump to: navigation, search [edit]
Unicellular Organism
The organisms consisting of only one cell are
called unicellular organisms e.g. Amoeba, Paramecium etc.
[edit] Amoeba
1. It is mostly found in fresh water pond or
pool.
2. In the ponds, it is found moving about around
the weeds and stones. Some species are found in the moist soil.
3. Amoeba is a large protist.
4. It does not have the permanent shape.
5. Its size is about the end of pin or it
measures about 0.25mm. Therefore it is observed under the microscope.
6. Its structure is very simple.
7. It consists of nucleus and cytoplasm, which
are surrounded by a cell membrane.
8. Cell membrane protects it.
9. Cytoplasm is divided into two parts. Outer
clear and transparent part is called ectoplasm while the inner, viscous,
translucent and granular part is called endplasm.
10. Endoplasm contains food vacuoles of
different sizes. These food vacuoles help in the digestion of food.
11. The food of Amoeba consists of microbes present
in the water of pond.
12. Contractile vacuole maintains the
concentration of water in the body. It removes surplus water out of the cell.
13. In Amoeba, the exchange of gases and removal
of waste.
14. In Amoeba, there are also present
mitochondria, golgi bodies and ribosomes.
15. Nucleus changes its place with the movement
of the organism.
(Diagram)
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Tissues
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A group of cells which perform same function is
known as tissue. The tissues are divided into different types on the basis of
their form and structure or function.
Plant Tissues
Following are the types of tissues in plants:
1. Simple Tissues
2. Compound Tissues
Simple Tissues
Simple tissues consists of only one type of
cells. In plants, they are of following types:
1. Meristematic or embryonic tissues
2. Permanent Tissues
Meristematic Tissues
1. Cells of this tissue have ability to divide.
2. Cytoplasm is dense nd nucleus is big in these
cells.
3. Vacuoles are smaller if present other wise
absent.
4. All cells are identical.
5. There are no intercellular spaces.
6. Their walls are thin and nucleus is present
in centre of cell.
7. These tissues found on apex of root or shoot
are called apical meristems. The cells of these tissues divide; and redivide to
add primary tissue for elongation of setm or root.
This type of growth is called primary growth.
8. Meristematic cells are also found on the
lateral sides of roots and stems as lateral(cambium) or intercalary meristem,
and these add, secondary tissues. In this way, thickness of stem or root is
increased. This type of growth is called secondary growth.
Permanent Tissues
The cells of this tissue lack the ability to
divide and they originate from meristems. These are given below:
a. Epidermal Tissues
b. Ground Tissues
(a) Epidermal Tissues
1. They are found as the outermost covering of
leaf, stem or root.
2. There are non intercellular spaces.
3. Cells are rectangular in shape.
4. In the epidermal tissues of stem and leaves,
there are small openings called stomata for gaseous exchange.
(b) Ground Tissues
1. Most of the portion of body of herbaceous
plants consists of ground tissues i.e. parenchyma.
2. They are thin walled.
3. Cells are large in size.
4. Cells sometimes may develop the ability to
divide.
5. Their main functions are to prepare and store
food and water.
Supporting or Mechanical Tissues
These provide strength flexibility to the plant.
They are of following two types:
a. Collenchyma Tissues
b. Sclerenchyma Tissues
(a) Collenchyma Tissues
1. These consist of living cells.
2. Their walls are not uniformly thickened.
3. Usually walls are thickened at angles.
4. These are more flexible or elastic than sclerenchyma.
5. These tissues are found in stem, in midrib of
leaves and in cortex of petiole.
(b) Sclerenchyma Tissues
1. These consist of dead cells.
2. Their walls are highly thickened due to
deposition of lignin.
3. Lignin provides hardness and strength to the
cell.
4. These cells are without protoplasm.
5. Sclerenchyma cells are of two types,
- Stone cells having uniformly thick cell walls; found in
testa of seeds.
- Fibrous cells which are elongated cells found in xylem
and phloem for strength and transport of water
Compound Tissues
These are the tissues which consists of two or
more than two types of cells. But all cells perform a common function.
These Tissues are of following types:
Xylem Tissue
1. This vascular tissue transports water in the
plants and provides strength to the plant.
2. In this tissue, there are present xylem
parenchyma and two types of thick walled dead cells.
- Long cells which are called vessel elements or cells.
They are joined together to form long pipe-lines. These transport water
from roots to leaves.
- Spindle shaped cells, which are called tracheicts.
These provide strength to root and shoot etc.
3. Xylem conducts water in one
direction that is from roots towards the stem and leaves.
Phloem Tissues
1. This vascular tissue transports food in the
plants.
2. It helps in two directional conduction of
food material i.e. from leaves to roots and vice-versa.
3. This tissue mostly consists of living cells.
There are three types of cells
(a) Phloem Parenchyma
(b) Sieve Tube Cells
(c) Companion Cells
(a) Phloem Parenchyma
These cells store surplus water and food. They
can start to divide when needed.
(b) Sieve Tube Cells
Their end walls have small pores called sieve
plates. These cells join to form long pipelines, which are called sieve tubes.
There is no nucleus in these cells. Their main function is to transport food.
(c) Companion Cells
In some plants, each sieve tube cell is
accompanied by a companion cell. The companion cell has a nucleus. The corn
cell controls the movement of food through sieve tubes.
Animal Tissues
Following are four types of tissues that are
found in animals:
1. Epithelial Tissues
2. Connective Tissues
3. Muscle Tissues
4. Nerve Tissues
Epithelial Tissues
1. these are found as outer most layers of an
organ or as lining of body invaginations.
2. Their cells are long and flat.
3. These may form one or more layers of
epithelial tissues of skin which is called squamous epithelial cells.
4. Squamous Epithelium provides protection to
skin.
5. Some cells are cubical in shape and known as
cuboidal epithelial cells.
6. Cuboidal epithelial cells from the lining of
glandular ducts and help in the production of cell secretions.
7. Some cells are small and elongated which are
found at certain places in the inner lining of different organs and secret
juice. These are called columnar epithelial cells e.g. cells of gastric glands
in stomach which secrete the gastric juice.
8. Some columnar cells have cilia at their free
surface. These are called ciliated columnar epithelial cells e.g. cells present
in trachea. Due to movement of these cilia, mucous and other materials are
expelled.
Connective Tissues
1. This tissue is made up of semi fluid matrix.
2. These matrixes contain a variety of cells and
fibers.
3. These tissues provide support to different
body parts and bind them together. These also protect the organs from germs and
help in the production of blood cells.
4. These are of two types:
- Soft connective tissues e.g. fatty tissues and tendons.
- Hard connective tissues e.g. cartilage and bone.
5. Blood is also a special
connective tissue with cells suspended in the fluid medium. It transports
materials in the body.
Muscular Tissues
1. This tissue is made up of special contractile
cells or fibers.
2. The cells are elongated and are called muscle
fibers.
3. These cells have the ability to contract and
relax which results in movements of body and the organs.
4. Following are the three types of muscles in
our body.
Skeletal Muscles
These are attached to cartilage and bones. These
seem to be striped fibers under the microscope. Therefore these are striped or
striated muscles. Their movements are under our control so these are voluntary
muscles e.g. muscles of arm and legs which move these parts.
Smooth Muscles
These are found around hollow organs such as
blood vessels, gut. These produce slow, sustained contractions but do not
fatigue. These re composed of spindle shaped unstriated muscles. These are
involuntary and are under the control of the autonomic nervous system.
Cardiac Muscles
These are found in the heart. These are composed
of branched fibers and are capable of sustained contraction but do not not
fatigue. These are also involuntary in action.
Nervous Tissues
1. These are composed of nerve cells which are
called neurons.
2. Each neuron consists of a cell body, axon and
dendrites.
3. These productive nerve impulse to conduct
messages.
4. By this tissue, different body parts have
coordination with each other.
5. This tissue also forms brain and spinal cord.
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Mitosis
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It is that cell division in which the number of
chromosomes in both daughter nuclei remains same as in parent nucleus.
(Diagram)
Events of Mitosis
Mitosis has the following phases:
1. Prophase
2. Metaphase
3. Anaphase
4. Telephase
5. Cytokinesis
Prophase
1. In this phase, coiling of chromosomes starts
and their length decreases but diameter increases. It means that chromosomes
become shorter and thicker, this process is called condensation.
2. Microtubules arrange to form a structure
called spindle.
3. In animal cell, there are also present
centrioles on both poles of spindle. From each centriole, small microtubules or
fiber arise forming a star shaped aster.
4. Spindle fibers, centrioles and aster
collectively form mitotic apparatus. In plants, this apparatus is made up of
only spindle fibers as asters are absent in these cells.
5. Nuclear membrane is broken down. Nucleolus
disappears and chromosomes scatter over the spindle fiber.
6. Each chromosome consists of two similar
threads like structure called chromatids, these chromatids are united to each
other by means of centromere.
Metaphase
1. The chromosomes arrange themselves on equator
of the spindle to form an equatorial plate. In this condition, chromosomes
become more visible.
2. The chromosomes are attached at their
centromere to one spindle fiber from each pole.
Anaphase
1. First of all spindle fibers shrink and become
short.
2. The centromere of each chromosome then
divides and the two chromatids of each chromosome start separating. At this
stage these are not called chromatids because these are no in united condition
these are called chromosomes.
3. These chromosomes start moving slowly towards
the opposite poles. In this way, one set of chromosomes moves towrds one pole
while other towards the other pole.
Telophase
1. The chromosomes reach their poles.
2. The chromosomes uncoil and become less visible.
3. Nuclear membrane reforms and nucleolus
appears too. Therefore two nuclei are formed. Each daughter nucleus has the
same number of chromosomes as the parent cell.
Cytokinesis
The division of cytoplasm is called cytokinesis.
It begins at the last stages of nuclear division. In plant cell, cytoplasm
divides by formation of cell plate which is also called phragmoplast. It
gradually extends outward and finally two daughter cells are separated.
In animals, cytoplasm divides by furrowing.
During this, there occurs inward pinching of cell membrane resulting into two
daughter cells. In mitosis, two daughter cells are formed from one parent cell
which are identical to their parent cell.
Significance of Mitosis
1. Mitosis occurs in all types of somatic cells.
2. Daughter cells formed as a result of mitosis
have same number of chromosomes as that of parent cell. In this way, all cells
of body of an organism have same number of chromosomes.
3. Zygote divides by mitosis to form embryo and
after hatching or birth, mitosis continues up to maturity of an individual.
4. Mitosis also results in growth and repairing
of damaged or worn out tissues.
5. Healing of wounds is also due to mitosis.
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Difference between Prokaryotic Cell and
Eukaryotic Cell
Friendsmania.net Prokaryotic Cell
- The organisms made of prokaryotic cells are called
prokaryotes e.g. bacteria and cyanobacteria.
- These cells lack a membrane bound nucleus. The
hereditary material (DNA) is found in cytoplasm.
- These cells lack membrane bound organelles.
- Ribosomes are of small size in and freely scattered
cytoplasm.
- Cellulose is absent in cell wall, rather it is made up
of peptido-glycan or murein.
- These cells are simple and of smaller size (average
diameter 0.5 - 10 nm)
Eukaryotic Cell
- The organisms mae of Eukaryotic cells are called
Eukaryotes, e.g. animals, plants fungi and protists.
- These cells have a membrane bound nucleus; and
hereditary material is found inside the nucleus.
- These cells have membrane bound organelles.
- Ribosomes are of large size and are present in
endoplasmic reticulum free in cytoplasm.
- Cellulose is present in cell wall of plant cells. The
cell wall of most of fungi is composed of chitin.
- These cells are complex and of larger size (Average
diameter 10-100nm)
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Organelles
in Cytoplasm
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Mitochondria
They re oval or rod like in shape. Their
membrane is doubled. Outer membrane is smooth while inner membrane has
enfolding in the mitochondrial matrix. These enfolding are called cristae. The
cristae bear small rounded bodies which are called particles.
There are about one million elementary particles
in one mitochondrian. They are involved in oxidative phosphorylation. They also
have many respiratory enzymes.
Number of Mitochondria
Their number is different in different cells of
different animals. In more active cells, their number is more than 1000 e.g. liver
cell.s The cells of ear lobes have a few number of mitochondria.
Function
Mitochondria re very important organelles of
Eukaryotic cell.s Many oxidation-reduction reaction occur in the mitochondria.
As a result energy is produced. This energy is used by cell in various
functions. This the reason that mitochondria are also called "Power house
of cell".
Golgi Bodies
They were discovered by Camillo Golgi. They
consist of set of smooth, flattened sacs which are called cristernae. The
cristemae are stacked over each other. Golgi bodies are in the form of network
in some cells or meshwork or filamentous in other cells.
Function
Golgi bodies store the secretions, convert them
into finished products and pack them at their margins into small rounded sacs called
Golgi vesicles, which transport secretions outside the cell.
Endoplasmic Reticulum
It is a network of tubules and cristemae
extending throughout the cytoplasm from nuclear membrane to cell membrane.
Types of Endoplasmic Reticulum
Following are the two types of Endoplasmic
Reticulum:
Smooth Endoplasmic Reticulum
It is also called non-granular endoplasmic
reticulum because ribosomes are not attached on it.
Rough Endoplasmic Reticulum
It is also called granular endoplasmic reticulum
because ribosomes are attached on it.
Functions
1. Smooth endoplasmic Reticulum plays a role in
synthesis of lipids.
2. Rough endoplasmic reticulum plays an
important role in synthesis of proteins. It also transports materials from one
part of cell to other.
3. Endoplasmic reticulum provides support to the
cell.
Ribosomes
These are tiny granular structures. These re not
bounded by any membrane. These are formed in the nucleolus nd re freely
dispersed in cytoplasm or attached with endoplasmic reticulum.
Functions
Ribosome is involved in protein synthesis. It is
the only organelle which is also found in Prokaryotic cell.
Plastids
These are pigment containing organelles. These
are found in plant cells. Many plastids have one or more than one pigments.
Types of Plastids
Plastids are of three types which are as
follows:
Chloroplasts
These are mot important plastids. These re green
in colour and found in green parts of plant. These contain chlorophyll which
helps in photosynthesis. The study of ultra structure reveals that it is
bounded by a double membrane.
Inside the chloroplast there is present a
semifluid matrix called called stroma, which is made up of proteins and other
chemicals. The inner membrane forms stacked membrane system which becomes
suspended in the stroma. Each membrane stack is called granum (plural grana.
The membranes of grana are the sites where photosynthesis occurs in the
presence of sun light.
Functions
In chloroplasts, photosynthesis takes place and
food is prepared for plant.
Chromoplasts
These are second type of plastids. These are of
various colours other than green. In plants, colours other than green are due
to chromoplasts. These are present in the petals of the flowers and in the
ripened fruit.
Functions
These help the plants in pollination. These
impart various colours to petals and fruits.
Leucoplasts
These are third type of plastids. These are
colourless plastids. These are triangular tubular or of any other shape. These
are found in food storage prts of the plant especially the roots and tubers.
Centriole
In animal cells, two centrioles are present near
the nucleus. There are hollow and cylindrical. Each centriole consists of nine
triplets of microtubules.
Function
Centrioles help in spindle formation during division
of animal cell. Spindle is composed of protein fibers which help the
chromosomes to move. Centrioles are absent in cells of higher plants. In some
cells, centrioles help in the formation of flagella or cillia.
Vacuole
It is a fluid filled small sac which is bounded
by a single membrane. In animal cells, these are comparatively smaller in size
but many in number while in plant cells; there is a large central vacuole which
is filled with water and salts.
Functions
In small organisms, extra water and wastes are
excreted through contractile vacuoles, while food is digested in food vacuole.
Increase in size of vacuole results in an increase in size of cell.
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Structure
of Cell
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There are two types of cells:
1. Prokaryotic cell
2. Eukaryotic Cell
Prokaryotic cell lacks a membrane bound nucleus
and membraned organelles e.g. bacterial cell while eukaryotic cell has a
membrane bound nucleus and membraned organelles e.g. cells of plants and
animals.
With the help of light microscope and electron
microscope, a typical Eukaryotic cell shows the following structural details.
(Diagram)
1. Cell Wall
2. Cell Membrane
3. Nucleus
4. Cytoplasm
Cell Wall
It is the outer most boundary of plant cells. It
is rigid and non-living. It is chemically composed of Cellulose. The cell wall
of fungi is made up of Chitin. The walls of some cells are thick and walls of
some cells are thin. For example, in plants, xylem vessel elements and
tracheids (which transport water and minerals) have thick walls whereas as
parenchyma cells (which store water and food) have thin walls. The primary
layer of cell wall is known as primary walls which are further strengthened by
an additional layer called secondary wall especially in xylem vessels.
Secondary wall is thicker than the primary wall. Electron microscope studies
reveal that cellulose fibers in primary and secondary walls have a criss cross
arrangement.
Functions
Cell wall provides a definite shape, rigidity,
protection and support to plant cell.
Cell Membrane
It is a thin membrane which is also called
Plasma membrane. It is present in cells of all plants and animals. It is outer
most boundary of animal cell while in plant cells; it is present inner to cell
wall. Both nucleus and cytoplasm are surrounded by cell membrane. According to
fluid mosaic model, cell membrane is composed of two layers of lipids in which
protein molecules are partially or completely embedded.
Functions
Cell membrane is selectively permeable membrane.
It means that it allows some things to pass through easily while some not.
Thus, it controls the movement of material inside or outside the cell.
Nucleus
It is most important and distinct part of the
cell. It is present in center of the animal cell while in plant cell it is
pushed on one side due to large central vacuole. It is also surrounded by a
membrane which is called membrane. Under microscope, it to be doubled and
nuclear electron appears porous.
1. The number of chromosomes is fixed for each
species. This number is called diploid number (2n). E.g human's cell has 46
chromosomes, cell of Radish has 18 chromosomes, and cell of union has 16
chromosomes.
2. Chromosomes are composed of protein and DNA.
3. In the nucleolus (plural, Nucleoli) ribosomal
RNA is formed which helps in the formation of ribosome.
Cytoplasm
It is viscous opaque substance. It is present
between nuclear membrane and cell membrane. In a living cell, many types of
organelle of different sizes and shapes are found. It contains many insoluble
granules of storage substances. There are also present organic compounds like
carbohydrates, proteins, lipids (fats), enzymes and inorganic compounds like
water and salts.
Functions
Cytoplasm provides chemicals, site and
environment for different biochemical reactions
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Electron Microscope
This is the most advanced form of microscope.
Its resolving power is 250 times or more that of a compound microscope. In this
microscope, a beam of electrons under high voltage is passed through the object
and its image is reflected on to a screen through an electro magnetic lens to
make a photograph.
(Diagram)
With the help of microscope, any object an be
magnified up to 250,000 its original size.
Comparison of Light Microscope and Electron
Microscope
Light Microscope
* The radiation source is light so it is called
light microscope.
* Wavelength of light is 400 - 700 nm.
* Maximum resolution is 200 nm.
* Maximum useful magnification is X 1500 with
eye.
* Lenses are used.
Electron Microscope
* The radiation source is beam of electrons, so
it is called Electron Microscope.
* Wavelength of beam of electrons is 0.005 nm.
* Maximum resolution is 0.5 nm.
* Maximum useful magnification is X. 250,000 on
screen as image or photograph.
* Electromagnets are used.
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The
Discovery of Cell and Cell Theory
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Discovery of Cell
In 1665, an English biologist Robert Hooke
invented first compound microscope and observed the sections of corks and
leaves under this microscope. He noticed in them small box like chambers of
same size which he called "cells". After this, biologists observed
different organisms under the microscope. They found that structure of cells
was complex.
Cell Theory
In 19th century, the compound microscope was
highly advanced and biologists observed things just a micrometer apart. After
this, a series of discoveries started, which provided basic information for
cell theory.
1. In 1831 - 33, Robert Brown discovered nucleus
in cells of plants.
2. In 1838, a German botanist Mathias Scheiden
observed that all plants were made up of cells.
3. In 1839, Theoclor Schwann obsrved that the
bodies of of animals were made up of cells which were similar to plant cells.
4. Thus, Schleiden and Schwann formulated the
"Cell Theory". According to this, all organisms are made up of cells.
5. In 1840, J. Purkinji gave the name
"Protoplasm" to the things found inside the cells. At that time, cell
was considered as a bag of thick dense substance containing a nucleus.
Later on, resolving power and quality of
microscopes were highly improved. Section cutting of tissues and cells and
their staining became easier and better. It revealed that cell was not a simple
mass of granular substance; instead it contained many sub cellular bodies
called "Organelles". Each organelle has a definite job in the cell.
6. Human is made up of about 60 trillion cells.
From Amoeba and unicellular algae to whales and tallest red wood trees, all'
are made up of similar basic units called cell.s All animals and plants are
thus made up of cells and cell products.
Salient Features of Cell Theory
1. All animals and plants are made up of cells
and cell products. Among these some organisms are unicellular and some are
multicellular.
2. Cell is structural and functional unit of
living organisms.
3. New cells come from the divisions of
pre-existing cell.
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Introduction to Biology
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Science
Our universe operates under certain principles.
For understanding of these principles, the experiments are done and observations
are made; on the basis of which logical conclusions are drawn. Such a study is
called "Science". In brief science is the knowledge based on
experiments and observations.
Biology
The Scientific study of living organisms is
called Biology. The word biology is derived from two Greek words
"bios" meaning life and "logos" meaning thought, discourse,
reasoning or study. It means that all aspects of life and every type of living
organism are discussed in biology.
Branches of Biology
Biology is divided into following branches:
Morphology
The study of form and structure of living
organisms is called morphology. It can be further divided into following two
parts:
1. The study of external parts of living
organism is called external morphology.
2. The study of internal parts of living
organism is called internal morphology or anatomy.
Histology
the study of cells and tissues with the aid of
the microscope is called Histology.
Cell Biology
The study of structure and functions of cells
and their organelles is called Cell Biology.
Physiology
the study of different functions performed by
different parts of living organism is called Physiology.
Ecology
The study of organisms in relation to each other
and their environment is called Ecology or Environmental Biology.
Taxanomy
Living organisms are classified into groups and
subgroups on the basis of similarities and differences. This is called
classification Taxanomy is that branch of biology in which organisms are
classified and given scientific names.
Embryology
The study of development of an organism from
fertilized egg (zygote) is called embryology. The stage between zygote and
newly hatched or born baby is called embryo.
Genetics
The study of methods and principles of
biological inheritance of characters from parents to their offspring is called
genetics.
Paleontology
The body parts of ancient organisms or their
impressions preserved in rocks are called fossils. The study of fossils is
called paleontology. It also includes the study of origin and evolution of
organisms.
It can be divided into two parts:
1. The study of fossils of plants is called
Palaeobotany.
2. The study of fossils of animals is called
Palaeozoology.
Biochemistry
The study of metabolic reactions taking place in
living organisms is called biochemistry. These reactions may be constructive or
destructive. The assimilation of food is a constructive process and respiration
is a destructive process.
Biotechnology
It is the branch of biology which deals with the
practical application of organisms and their components for the welfare of
human beings e.g. disinfections and preservations of food, preservations of
insulin and biogas from bacteria etc.
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Relationship of Biology with other Sciences
In ancient times, there was no distinction of
biology and other sciences. Different fields of sciences like biology,
chemistry, physics and mathematics are met together in the writings of ancient
scientists. In ancient times, these subjects were studied under one head
"science", but with the passage of time, the science developed very
much and the huge scientific knowledge was then divided into different
branches.
However even today the interrelationship of
these branches cannot be denied.
Biophysics
The study of various biological phenomena
according to principles of physics is called biophysics. For example, movement
of muscles and bones based on principles of physics.
Biochemistry
The study of different biochemical like
carbohydrates, proteins and nucleic acids etc found in cells of living
organisms and hundreds of the underlying chemical reactions in cells of
organisms is called biochemistry.
Biometry
The data obtained from observations and
experiments on living organism is analyzed by various statistical methods. This
is called Biometry.
Biogeography
The study of plants and animals and the basis of
geographical distribution is called Biogeography.
Bio-Economics
The study of living organisms from economic
point of view is called Bio-Economics. It includes the study of cost
effectiveness and viability of biological projects from commercial point of
view.
Biological Method of Study or Method Used to Solve the Problem of Malaria
Observation
Most of the biological investigations start with
an observation. After selecting, specific biological problem, observations are
made to collect relevant information. For example; take the case of Malaria.
Malaria is the greatest killer disease of man for centuries. Malaria was one
among many other diseases for which a cure was needed.
In 1878, A French physician, Laveran, studied
the blood sample of Malaria patient under microscope and observed tiny
creatures in it. These creatures were later called Plasmodium.
Hypothesis
To solve a scientific problem, one or more
possible propositions are made on the basis of the observations. Such a
proposition is called a Hypothesis. The hypothesis is tested by scientific
method.
Merits
A good hypothesis has the following merits:
1. It is close to the observed fact.
2. One or more deductions can be made from this.
3. These deductions should be confirmed doing
experiments.
4. Results whether positive or negative should
be reproducible.
To know the cause of malaria, following
hypothesis was made:
Plasmodium is the cause of Malaria."
Note: One or more than one possible deductions
can be made from the hypothesis.
Deduction
the logical conclusion drawn from a hypothesis
is called deduction. Testing one deduction and finding it correct does not
necessarily mean the hypothesis is correct and scientific problem is solved.
Actually, if more deductions are found to be correct; the hypothesis will be
close to solution of the problem.
Experiments
Following groups are designed to perform
experiments:
Experimental Group
It is the group of those people who are affected
in some way and we do not know the real cause e.g. a group of malarial
patients.
Control Group
It is the group of unaffected people e.g.
persons group of healthy persons.
By keeping both of these groups under similar
conditions, the difference between them is determined. To know the real cause
of malaria, the experts examined the blood of about 100 malarial patients
(experimental group). On the other hand, the experts examined the blood of about
100 healthy persons (control group).
Results
During the experiments mentioned above; the
plasmodium was found in blood of most of malarial patients. The plasmodim was
absent in the blood of healthy persons. These results verified the deductions
and thus the hypothesis i.e. the plasmodium is the cause of Malaria, was proved
to a considerable extent.
Theory
If hypothesis is proved to be correct from
repeated experiments and uniform results, then this hypothesis becomes a
theory.
Scientific Principle
When a theory is again and again proved to be
correct, then it is called a scientific principle.
Contributions of Muslims Scientists in the Field of Biology
Many Muslim scientists contributed a lot in the
field of biology but the following names are more respectable:
Jabar-Bin-Hayan
Period: 722-817 A.D
Books: Alnabatat and Alhaywan
Contribution: He studied the life of plants and
animals and wrote many books about them.
Abdul-Malik-Asmal
Period:741 A.D
Books: Al-Kheil, Al-Ibil, As-Sha, Al-Wahoosh,
Khalaqul Insan.
Contributions: He described the body structure
and functions of horses, camels, sheep, wild animals and human beings in
detail.
Abu-Usman-Umer Al-Jahiz
Books: Al-Haywan
Contribution: He explained the characteristics
of about 350 species of animals. He wrote on the life of aunts especially.
Al-Farabi and Abu-ul-Qusim Al-Zahravi
Period: 870-950 A.D
Books: Al-Nabatat, Al-Haywanat
Contribution: The above mentioned books were
written by Al-Farabi. On the other hand, Al-Zahravi was famous for removal of
stone from urinary bladder.
Ibn-ul-Haitham
Period: 965-1039 A.D
Books: Al-Manazir, Mizan-ul-Hikma
Contributions: Both of these books were famous
and well known at that time. These books were translated into Latin, Hebrew,
Greek and other western languages. He explained the structure and functions of
eyes and suggested the cornea as a site of vision.
Bu-Ali Sina
Period: 980 A.D
Book: Al-Qanoon Fil Tib Al-Shifa
Contribution: He wrote about plants, animals and
non-living things in one book. He was expert in mathematics, astronomy, physics
and paleontology.
Ibn-ul-Nafees
Contribution: he described the blood circulation
in the human body.
Ali Ibne Isa
Contribution: He worked on structure, functions
of eye and about 130 diseases of eyes and their treatment.
Non-Muslim Scientists
There is long list of non-Muslim scientists who
contributed a lot in the field of biology. But, the following scientists are
very well known.
Aristotle
Period: 382-322 A.D
Book: Historia Animalia
Contribution: He classified the animals and
called as founder of biological classifications. He classified animals into two
units, genus and species which was called Oedos.
Theophrastus
Contribution: He accepted sex in plants and
desired about 500 plants. He is known as father of botany.
Visalius
Period: 1514-1564 A.D
Contribution: He wrote a book on human body
structure in which he described bones, muscles and orans in detail.
William Harvey
Period: 1578-1657 A.D
Contribution: He described the blood circulation
in human body.
Carolous Linnaeus
Period: 1507-1778 A.D
Contribution: He described the blood circulation
in human body.
Carolous Linnaeus
Period: 1578-1657 A.D.
Contribution: He gave a system of binomial
nomenclature. He is known as father of taxonomy.
Schlelden and Schwann
Contribution: Scheiden (1838) studied the cells
of plants and Schwann (1839) studied the cells of animals. They proposed the
cell theory.
Louis Pasteur
Period: 1822-1895 A.D
Contribution: He proved that microbes are found
in the air which spoils the food items.
Edward Jennar
Period: 1796 A.D
Contribution: He invented method of vaccination
against Small Pox.
Robert Koch
Period: 1845-1910 A.D.
Contribution: He discovered bacteria as causes
of main diseases like Tuberculosis.
Joseph Lister
Period: 1860 A.D
Contribution: He made antiseptic medicines like
Iodine and Carbolic acid.
Charles Darwin
Period: 1859 A.D
Book: Origin of Species by Natural Selection
Contribution: He explained concept of evolution
in his book.
Gregor Mendel
Period: 1822-1884 A.D
Contribution: He conducted experiments on Pea
plants. He formulated the laws of inheritance. He is known as father of modern
genetics.
William Lawrence and William Henry
Period: 1882 A.D
Contribution: They discovered X-ray
crystallography to understand the structure of deoxyribonucleic acid (DN). They
were father and son.
Francis Crick and James Watson
Period: 1953 A.D
Contribution: He discovered the double helix
model of DNA and proved that DNA is found in cells of all living organisms.
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Significance of Biology or Impact of Biological Study on Human Life
the present high level achievements of man are
largely due to the advanced biological research. The study of biology is very
important in routine matters of our life as described below.
Food Production
Food has basic importance in our life. Due to
researches in biology, there are great achievements in agriculture. For the
production of cereal crops; the best varieties of seeds were selected. The
yield of wheat corn, rice, sugarcane and cotton has been enormously increased
bringing healthy effect and prosperity. Today, the man has overcome the
problems of balanced diet, food storage and famine.
Control on Diseases
Health is basic necessity of life. Due to
researches in biology, the discovery of new antibiotics for many infectious
diseases like plague, cholera, pneumonia, tuberculosis and typhoid has made the
life easy. The infant mortality has reduced due to discovery of vaccines for
fatal diseases like small pox, polio, tetanus and diphtheria. Today AIDS is
problem for world. The germs of this disease destroy the natural resistance and
immunities against diseases.
A medicine called AZT has been found effective
for AIDS. Similarly many drugs have been discovered for treatment of cancer.
Many organisms are used to produce drugs e.g. bacteria and fungi. We have
controlled many infectious diseases by using drugs like penicillin and
streptomycin. We have eliminated many harmful pests like locusts, flour beetle,
termites, fungi, shipworm etc by using pesticides.
Genetic Engineering
Genetic engineering is a technology in which
useful genes are inserted into the bacteria etc, to get required beneficial
results. Using this technique, manipulation of heredity material is done and
new species are produced e.g. Doli sheep. Today human insulin gene is inserted
into DNA of bacteria to synthesize insulin on commercial bases. This insulin is
found to be very useful in treatment of diabetic patients.
Pollution Control
Due to increasing urbanization,
industrialization and automobiles, the man and other organisms have to face a
great danger, "the environmental pollution". due to pollution of air,
land and water there is danger to humans aid wild life. Many plants and animals
have been maintaining the balance in our environment for millions of years and
now at the verge of extinction due to pollution. By biological research,
scientists are busy to find out causes and ways to control the pollution. The
biology thus, has greatly improved the quality of our life.
Space Biology
On Mars, some evidence of life has been found
which is still under further investigation. During exploration of space the
scientists have been conducted experiments on different plants, animals, fungi
and bacteria in space and they have obtained very useful information.
Islamic concepts About Origin of Life
We have got much information about origin of
life by studying the Holy Quran.
Ultimate Creator
The first thing learnt from teachings of Quran
is that Allah is the ultimate creator of everything whether plants, animals or
non-living things.
"Allah is the creator of all things and He is Guardian of overall
things." - (Surah Zamar-Ayat 62)
Not only plants, animals and non-living things
and human beings but also the heavens and whole universe have been created by
Allah.
Origin of Life from Water
The second important fact we get from Quran is
that Allah has created all living thins from water.
"We made every thing from water." - (Sura Ambia - Ayat 30)
Viruses, bacteria, algae, fungi, different
plants, all animals and humans are all living things. According to Quranic
verses, all diverse living things were created from water.
Common Origin
From above mentioned sayings of God there is an
indication for common origin of living things or we can at least say that all
living things have come out from water.
Creation of Man
Allah also sys in Quran:
"He created man from clay like the potter's." - (Sura Rehman -
Ayat 14)
It seems that there were following two sages for
creation of man:
1. Creation from water.
2. The first created thing, on admixing with
clay was transformed into more advanced beings.
The same can also be applied to other animals because
there are certain similarities between structure of man and other animals. In
vertebrate animals, the structures of digestive system, respiratory system,
blood circulatory system, excretory system and reproductive system etc are
similar to great extent, although differ in other details. Reproduction in
living things.
Once the life had been created, Allah
implemented the process of reproduction for the continuity of races of animals
and other organisms. The various stages of reproduction have been described in
sura in following way:
"Then fashioned we drop a clot, then fashioned we clot a little
lump, then fashioned we the lump bones, then clothed the bones with
flesh." - (Sura Almominoon Ayat 14)
Classification and Evolution
"Allah has created every animal from water some of them creep up on
their bellies, other walk on two legs, and others on four, Allah creates what
the pleases. He has power overall thins." - (Sura Nur Ayat 45)
"Hath there come upon man (every) any period of time in which he was
a thing unrememberd?" - (Sura Dahar Ayat 1)
The close study of above sayings of God reveals
that all animals had a common origin but they gradually underwent changes after
words and became different from each other i.e. some animals became crawler,
some bipedal and some other tetra pods. The present animals are advanced forms
of the past animals who achieved this form after passing through many changes.
Concept of Abiogenesis and Biogenesis for Origin of Life on Planet Earth
Scientific Views About Origin of Life
How did life originate on this earth? This may
never be know for certain to science because neither it is possible today to
make observation of primitive events when the life actually originated nor
there is any fossil record of first formed soft bodied organisms. However, in
1950 some scientists created the primitive earth condition (approximately 4
billion years ago) in the laboratory and performed experiments. On the basis of
results obtained from these experiments, scientists formulated some ideas.
These ideas seem to be close to reality.
Abiogenesis and Biogenesis
In ancient times, there were two views about the
origin of life:
1. According to one view, offspring are produced
from their parents by process of reproduction, this is called concept of
Biogenesis.
2. According to other view, living things are
produced spontaneously from non-living things. This is called concept of
Abiogenesis.
Because at that time, there was neither so much
advancement in science nor scientific tools like microscope and other
instruments were invented, which could help in detailed observations about
reality. According to some people, insects are produced from dewdrops, rats
from debris, frogs from mud, and maggots from putrefied meat. Some scientists
like Copernieus, Bacon, Galileo, Harvey, and Descartes also believed this
concept.
From 16th to 18th century many scientists
performed experiments to test this concept. They found some animals to be
developed from non living matter. Therefore this concept seemed to be correct.
Later on, scientists performed experiments with
more care. First of all an Italian scientists, Francesco Redi, (1668) proved
that this concept was wrong.
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Redi's Experiment
Redi took four bottles. He put a dead snake in
one bottle, a few dead fish in second bottle, dead eel in third bottle and a
piece of meat in the fourth bottle. All these bottles were left open. The flies
could enter these bottles. Then he took four more such bottles. He put some
dead animals in all four bottles but covered the mouth of bottles.
(Figure from book)
After few days, maggots were produced in four
open bottles. Maggots were not produced in closed bottles. Moreover, no flies
were seen. Therefore, it was proved that maggots were not produced
spontaneously by produced due to flied which were visiting the open bottles.
The maggots were the larvae produced from the eggs of the visiting flies.
Needham's Experiment
In 1948, an English scientist Needham boiled the
meat in the water and prepared gravy. He poured this gravy into the bottles and
closes their mouth with corks. After some days, many microscopic organisms were
produced. In this way, the believers of abiogenesis were once again gain
courage.
(Figure from book)
Experiment of Spallanzani
In 1767, an Italian scientists Spallanzani
criticized the experiment of Needham. He said that air entered the bottles
through the pores of cork and hence living organisms were produced.
(Figure from Book)
Spallanzani put the boiled meat and vegetables
in clean bottles and then sealed the mouth of bottles by heat. He placed these
sealed bottles in boiled water to kill the possible germs. After some days, he
found no organisms. He left the same boiled meat and vegetables in open bottles
at the same time. Some living organisms were produced in these bottles. This
supportd the concept of Biogenesis. But the believers of Abiogenesis said that
air removed by Spallanzani was necessary for living things so no organisms were
produced in sealed bottles. When oxygen was discovered the supporters of
Abiogenesis said that Spallanzani had removed oxygen where by no life could be
produced in his experiment.
Experiment of Louis Pasteur
The argument on Biogenesis and Abiogenesis continued
up to the middle of, 19th century. A well-known French scientist, Louis Pasteur
proved, after simple but very careful experiments, that abiogenesis could not
occur in present environment of earth. He proved that living organisms could
only be produced from their parents.
In 1864, Pasteur performed his experiment in
front of the commission formed to solve the issue. He took flasks, which had
long curved S-shaped necks. He placed fermentable infusion (Yeast + sugar +
water) in flasks and left their mouth open.
(Figure from Book)
He boiled the yeast infusion in the flasks.
After this, he allowed to cool them and kept them as such. He observed that no
life ws produced even after the lapse of several days, because microscopic
organisms entering along with air got stuck up in on the curved walls of the
glass necks. Then he broke up the curved necks, so that air containing
microscopic organisms could reach the infusion. Now he noted that microscopic
organisms were produced within 48 hours. This proved that if care was taken and
no microscopic organisms and reproductive structures (eggs or spores) approach
the infusion, no life could be produced because thee is no spontaneous
generation of life from non life. After Pasteur, no further experiments were performed
on origin of life for the next 60 years. In 1920, a Russian biochemist
Alexander Oparin and a British biologist J.B.S 1-Ialdane suggested that life on
earth was originated after a long and gradual molecular evolution and there was
no spontaneous and miraculous origin of life on earth.
Chemical and Organic Evolution of Life on Earth
The modern view of the origin of life stresses
on the idea of chemical evolution. According to Oparin and Haldane, the origin
of first life had been initiated from the time of the existence of the solar
system (the sun with its nine planets). The earth, like the sun was made up of
light and heavy elements. Heavy elements like iron, nickel etc were present in
the nucleus of the earth, while the light elements and compounds like hydrogen,
methane, nitrogen, carbon, ammonia, nitrogen oxide, etc in the form of vapours
existed on the surface of the earth. These light elements and compounds were
responsible for the first life on earth.
The earth had high temperature and radiation and
had frequent and abundant discharges. In these conditions, the first life
originated. Oparin and Haldane suggested that simple inorganic molecules slowly
and gradually combined to produce complex organic molecules from which the
simplest form of life (bacteria) came into existence. This process took a long
time.
Haldane proposed that primitive earth's
atmosphere had only carbon dioxide, ammonia and water vapours. If a mixture of
these gases is exposed to ultraviolet radiation, it leads to the formation of
organic compounds like sugar and amino acids. As free oxygen was not available
to check the radiation from reaching the earth so substances like sugar and
amino acids went on accumulating under such conditions.
About 15 billion years ago, there was a huge
explosion (Big Bag). The universe started expanding and the temperature dropped
drastically. In time, about 4.6 billion years ago our earth and other planets
appeared as part of the solar system. The primitive atmosphere of the earth was
rich in hydrogen.
With the passage of time, the atmospheric
temperature gradually dropped. This allowed condensation and heavy rains, which
caused formation of oceans. Thunder and lightning sparks together with
ultraviolet radiation caused reactions of the atmospheric gases resulting in
the formation of simple organic molecules. These molecules came down with the
rains and accumulated in the seas, oceans, lakes, rivers and the soil over a
very long period of time. These molecules interacted and produced amino acids
and proteins which are the body building substances.
The fossil evidence indicates that the earliest
forms of organisms lived about 3.8 billion years ago. From this it is
speculated that the origin of life started about 4 billion years ago.
The earliest organisms were heterotrophs. The
depletion of the pre-existed food from the environment led to the evolution of
organisms capable of making their own food. They became autotrophs, and added
free oxygen into the atmosphere.
For at least the first 2 billion years of life
on earth, all organisms were bacteria. About 1.5 billions years ago, the first
eukaryotes appeared.
The idea of organic evolution was supported by
scientists like Lamarck and Charles Darwin.
Differentiate between Biogenesis and Abiogenesis
Biogenesis
- A theory which describes the origin of life on the
earth from pre-existing living organisms is called Biogenesis.
- It was based on practical experiments and material
evidence.
- It was supported by the experiments performed by Redi
and Pasteur.
- It was based on practical basis.
- It describes the process of reproduction as an
essential ability of living organisms.
Abiogenesis
- A theory which describes the origin of life on the
earth from non living things is called Abiogenesis.
- It was based on observations and national thoughts.
- It was supported by the fungus of bread: and production
of frogs in the mud.
- It was based on theoretical basis.
- It gives no scientific reasoning about the production
of life.
Differentiate between Hypothesis and Theory
Hypothesis
- The process of making some possible answers for the
related biological problem is called Hypothesis.
- It is the step of biological methods which gives the
way to carry on the research.
- Hypothesis is an uncertain intelligent statement.
- Hypothesis is formed from observations and collected
facts.
Theory
- The final explanation which is given on the basis of
hypothesis and deduction if they are found correct is called theory.
- It is the step of biological method which gives actual
reason to biological method.
- Theory is certain intelligent statement.
- Theory is formed by experimentation, physical evidence
to explain the laws of nature.
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Structural
Organization of Life
Friendsmania.net
IX Biology - Chapter 2 - Structural Organization
of Life
Friendsmania.net
* The Discovery of Cell and Cell Theory
* Electron Microscope
* Structure of Eukaryotic Cell
* Organelles in Cytoplasm
* Difference between Prokaryotic Cell and Eukaryotic
Cell
* Mitosis
* Meiosis
* Tissues
* Unicellular Organism (Amoeba)
* Multicellular Organism (Brassica Plant)
* Frog
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Classification
of Living Organisms
Friendsmania.net
Classification
The arrangement of organisms into groups and
subgroups on the basis of similar characters is called classification.
Basis of Classification
The classification of organisms is based on such
features or characters, which are similar in one kind of organisms and
different in different kind of organisms. These characters may be about
internal morphology, (anatomy), external morphology, physiology, cell
structure, especially the number of chromosomes and chemical composition (especially
of proteins) and embryology of the organisms. These characters help in study of
intra specific (within the same species) and intra specific (between different)
species differences.
The presence of similar characters in different
organisms indicates their common ancestory. This similarity because of common
ancestral origin is called Homology e.g. arm of a monkey, flipper of a whale
and wing of a bat show homology. They are dissimilar apparently but their
internal structure (arrangement of bones and muscles) is same. These organs are
called homologous organs. Due to this homology, we can, say that monkey, whale
and bad had common ancestors and are placed in same large group
"vertebrate". This homology is proved to be very helpful in
classification.
Aims/Objectives of Classification
These are given below:
1. To determine similarities and differences
between different organisms.
2. To arrange organisms on the basis of
similarities and differences.
3. To identify the organisms on the basis of
their structure and other prominent characters and study them systematically
and logically.
4. To find out inter-relationships of organisms.
First of all, Aristotle classified the organisms
on the basis of their resemblances. After this, Theophrastus classified the
plants. Then, after a long time, Carolous Linnaeus (1707-1778), suggested a new
system of classification. In this way, he started modem taxonomy.
Units of Classification
The basic unit of classification is specie
(Plural specie). A species is a group of organisms that can breed with one
another in nature and produce fertile offspring. All members of a species have
same number of chromosomes and also have many other features in common. All the
mustard plants belong to one species. All the human beings belong to another
species. The members of one species differ from members of other species and do
not breed naturally with each other. Such different species, which are closely
related, they are grouped in large group called genus (plural; genera) e.g.
Brassica is a genus. It includes several species like mustard, cabbage and
turnip. Similarly, Felis is a genus. It includes several species like lion,
tiger and cat. Similarly, many closely related genera are placed in a bigger
group called Family, families are grouped into an order, orders are grouped
into a class and classes are grouped into a phylum (plural, phyla) or division
(plural; division) in case of plants. The phyla or divisions are grouped into
kingdom. All these units are divided into subunits e.g. sub genus, sub phylum
and sub kingdom etc. The smallest the group or unit, the organisms found in
this group, would be more similar, they have more number of of similar
character.
Difference between Homologous and Analogous Organisms
The fruit of all plants, whether sweet, or sour,
small and dry or large and fleshy, all are the homologous structures because
they develop from ovary of flower. Their origin is common. On the other hand,
wings of an insect, and a bird, despite having same function, are not homologous
because their origin is different. Similarly green leaf of moss plant and that
of any vascular plant are not homologous. These organs are similar in function
but different in basic structure and origins are called analogous organs.
Biological Classification of Mustard Plant
Common Name ----------------- Mustard
Phylum or Division ---------- Anthophyta
Class ----------------------- Dictyledonae
Order ----------------------- Capparales
Family ---------------------- Brassicaceae
Genus ----------------------- Brassica
Species --------------------- Brassica
Campestris
Classification of Human Beings
Common Name ---------------- Human
Kingdom -------------------- Animalia
Phylum --------------------- Chordata
Class ---------------------- Mammalia
Order ---------------------- Primates
Family --------------------- Hominidae
Genus ---------------------- Homo
Species -------------------- Homo sapiens
Scientific Name ------------ Homo sapiens
Kingdoms of Organisms
The classification is not static, nor has only
one system of classification been followed rather it is dynamic. Whenever any
new knowledge is available about organisms, it is used in classification.
Therefore, many systems of classification have been used. Living organisms are
classified into two to five kingdoms.
Two Kingdom Systems
All organisms were classified into two kingdoms
before present time.
1. Plant Kingdom (Plantae) - It includes all the
small and large plants.
2. Animal Kingdom (Animals) - It includes all
the animals.
Important Characters of Plants and Animals
Presence of cell wall and ability to prepare
their own food were considered the most important characters of plants.
Lack of cell wall and inability to prepare food
and characteristic mode of nutrition and especially the ability to locomote
were considered the most important characters of animals.
Plant kingdom and animal kingdom were divided
into large groups.
Binomial Nomenclature
The method of giving scientific names to
organisms is called nomenclature. Same animal or same plants may be known by
different names. It must have one scientific name so that there may be no
confusion. To give such names to living organisms, the method was formulated by
carolous Linnaeous (1753). This method is called Binomial Nomenclature. Because
tis system is simple and comprehensive, so it is accepted and used in whole
world.
Rules of Binomial Nomenclature
1. According to this method, every species of
living organisms is given a Latinized scientific name consisting of two parts.
2. The first part is the name of genus and is
called generic name. It starts with a capital letter.
3. The second part is the name of species and is
called specific name. It starts with a small letter.
4. Both parts of scientific name of a species
are either underlined separately or italicized.
The scientific name of mustard plant is Brassica
campestris. The scientific name of rose plant is Rose indica. Similarly the
scientific name of frog is Rana tigrina and that of human is Homo sapiens.
Significance of Binomial Nomenclature
Before establishment of binomial nomenclature,
the names of organisms consisted of many words. These words were based on the
characters of these plants or animals. In different countries, even in
different parts of same country; local names were used for plants and animals.
The same organism may be given different names e.g. turnip, shaljam, gongloo,
thipar, and gogroon are all names of same plant. In England, there are at least
fifty names for pansy. Similarly a single common name may be used for different
kind of organisms e.g. the word "raspberry" is used for about 100
kinds of plants. This confusion can be avoided by giving each organism a
scientific name according to binomial nomenclature proposed by Carolous Linnaeus
in 1753. It is adopted by all taxonomists.
Biological Classification of Man
Common Name ----------------- Man
Kingdom --------------------- Animalia
Phylum ---------------------- Chordata
Class ----------------------- Mammalia
Order ----------------------- Primates
Family ---------------------- Hominidae
Genus ----------------------- Homo
Species --------------------- Homo sapiens
Biological Classification of Frog
Common Name ----------------- Frog
Kingdom --------------------- Animalia
Phylum ---------------------- Chordata
Class ----------------------- Amphibia
Order ----------------------- Salientia (Anura)
Family ---------------------- Ranidae
Species --------------------- Rana tigrina
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Virus, Bacteria and Cyano Bacteria
Friendsmania.net
Micro-Organisms
A large number of living things are present in
this world. Some of them are large and some are small. Majority of the
organisms are so small that they re not seen with naked eyes. For their
observation, we need a light microscope or even an electron microscope. These
microscopic organisms are called micro-organisms.
Micro-organisms As a Heterogeneous Group
Micro-organisms are a heterogeneous group. It
includes different kinds of organism viruses, bacteria, cyanobacteria,
protozoa, certain algae and some fungi. On the basis of structure they range
from sub-cellular to cellular for example, viruses are sub-cellular and all
other micro-organisms are cellular. Bacteria, and cyanobacteria are prokaryotes
(without nucleus) where as algae, fungi and protozoa are eukaryotes (with
nucleus). On the basis of mode of nutrition algae are autotrophic while fungi
and protozoa are heterotrohic. Therefore, micro-organisms differ in their
structure and mode of characteristics of viruses, they are studied in a
separate group where as bacteria and cyanobacteria, being prokaryotes, are
included in kingdom Monera.
Viruses
1. Virus is a Latin word which means "Poison".
Viruses are so small that they can only be seen with electron microscope.
2. Viruses have charcteristics of both living
and non-living things.
3. Structurally they are not like, cell and are
only made up of proteins and nucleic acids.
4. When they enter the body of any living
organisms, they reproduce there like living organism.
5. They look like non-living crystals when they
are out of the body of a living organism.
6. That is why they are placed between living
and non-living things.
7. All viruses are parasites and cause different
diseases in their hosts.
8. Viruses were discovered by Iwanowsky in 1892
from infected tobacco leaves. In 1935 W.M. Stanley isolated viruses in
crystalline form from infected leaves of tobacco and observed them under electron
microscope.
Size of Virus
Viruses are of different sizes. Their size
varies from 0.01um to 0.03um(um is micrometer = 1/10,00,000 meter)
Shape of Virus
Viruses are of different shapes some are
rounded, few are rod shaped, few polyhedral while some viruses look like
tadpoles.
Structure of Virus
Viruses have same biochemical nature. In spite
of their different shapes, they are made up of only two parts, an outer
"coat", and an inner "core". The core is made up of DNA or
RNA (never both) and the coat is made of protein. The outer protein coat
determines the shape of viruses. e.g. in bacteriophage (virus that lives in
bacteria) protein coat consists of two parts, head and tail. DNA is present in
the head region but the tail has only protein. Most of the animal viruses
contain DNA whereas plant viruses have RNA core bacteriophage is also called
phage virus.
Viral Diseases in Plants
Ring spot in different plants, yellow in sugar
beet and mosaic disease in tobacco, potato, tomato, bean and cabbage are the
various diseases of plants, caused by viruses.
Viral Diseases in Animals
Mouth and foot disease in cattle and cowpox in
horses, buffalo and cows are caused by viruses.
Viral Diseases in Humans
In human beings, viruses produce common cold,
influenza, small pox, yellow fever, polio, infectious hepatitis, cancer and
AIDS.
Ways of Viral Transmission
1. Through droplets produced during coughing and
sneezing.
2. Through contact.
3. By air, contaminated water and food.
4. Through insects.
5. By reuse of already used syringes.
6. By un-sterilized surgery equipments.
Bacteria
Bacteria are found every where in air, water,
living and dead bodies of organisms and even in glaciers and hot springs. These
are unicellular micro-organisms.
Discovery of Bacteria
Leeuwenhoek discovered bacteria in 1697 for the
first time. Later, Louis Pasteur and Robert Koch worked on them. They
discovered that bacteria produce many diseases in men and animals.
Size of Bacteria
Bacteria (singular : bacterium) range from 1um
to 10um in length and from 0.2um to 1um in width and can be observed under
light microscope.
Types of Bacteria
On the basis of shape and form, bacteria are of
four types. These are as follows:
1. Rounded - Cocci (singular; coccus)
2. Rod-like - Bacilli (singular; bacillus)
3. Spiral shaped - Spirilla (singular;
spirillum)
4. Comma like - Vibrios (singular; vibrio)
Bacteria occur both singly and in colonies.
Cocci bacteria are found in groups of two or four, or in irregular groups and
even in the form of long beads. Baccilli are found singly or may join end to
end to form long threads. But Spirilla and Vibrios occur singly.
(Diagram)
Structure of Bacteria
1. Bacteria are single celled prokaryotic
organisms.
2. Bacterial cell is surrounded by a cell wall
which is made of carbohydrates and amino acids.
3. Some bacteria have an additional slime
capsule around their cell wall, which protects them and prevents them from
drying.
4. Ribosomes help in synthesis of proteins.
Nucleus is absent in bacterium. However, only a single large circular molecule
of DNA is present which is surrounded by a clear zone of cytoplasm. It is known
as nucleoid. This is not bounded by a nuclear membrane.
5. In addition to main bacterial DNA small,
circular molecules of DNA called plasmids are also found. Plasmids play an
important role in transmission of some heredity characteristics. Plasmids are
also used a vectors in genetic engineering.
6. Motile (which can move) bacteria like bacilli
are spirilla have one or more thread like flagella (singular; flagellum) which
help them in their locomotion. Non motile bacteria like cocci lack flagella.
Economic Importance of Bacteria
It is generally thought that bacteria are fatal
and harmful organisms and there is no beneficial aspect. But this is wrong
impression. There are number of bacteria which are not only beneficial for
mankind but are also essential for living system. Bacteria play very important
role in the life of living organisms.
Beneficial Bacteria
Ecological Importance
These, along with fungi, help to decompose dead
organisms and their refuse into simpler substances replenishing the raw
materials in the soil and atmosphere and can thus purify the environment.
Bacteria and Nitrogenous Compounds in Soil
These bacteria are called nitrogen fixing
bacteria. Another kind of bacteria live in the soil, called nitrifying bacteria
which convert ammonia into nitrite and then to nitrate, enhancing the amount of
nitrogen in the soil. In this way fertility of soil is increased.
Industrial and Commercial Purposes
1. These are used in manufacturing butter,
cheese and yogurt.
2. These are used in processing of commercial
fibers, leather, coffee, tobacco and vinegar.
Bacteria Synthesize Enzymes
Bacteria synthesize cellulose enzyme in the
stomach of herbivore animals which helps in the digestion of food. Some
bacteria also synthesize vitamin "B" and "K" in the large
intestine of man and other mammals.
Bacteria as Bio-Insecticides
Recently the use of bacteria in bio-insecticides
has become popular.
Harmful Bacteria
1. Bacterial decomposition on one hand is
beneficial but on other hand causes damage to food, wood, clothes and other
things.
2. Denitrifying bacteria in soil decrease the
amount of nitrogen in soil and reduce the soil fertility. These are called
identifying bacteria.
3. Many bacteria are harmful and cause many
diseases in plants, such as canker disease in citrus fruits, rot and fire
blight in peach, pear and apple, and potato scab in potato.
4. In animal like cattle bacteria cause T.B and
anthrax. Bacteria also cause many diseases in man like T.B, Whooping Cough,
Diphtheria, Typhoid, Pneumonia, Tetanus, Plague, Bacterial Dysentery, Cholera,
Leprosy etc.
Ways of Bacteria Transmission
1. Whooping cough, Diphtheria, T.B and Pneumonia
causing bacteria are transmitted from one person to other person through
sneezes and cough droplets released in air.
2. Bacteria causing Typhoid and Cholera, are
transmitted from one organism to another through contaminated water and food.
3. Plague and bacterial dysentery read through
vectors like flies and animals.
Cyanobacteria
1. Cyanobacteria are also called blue green
algae. They are simplest living organisms which have the ability to manufacture
their own food by photosynthesis.
2. Structurally they resemble bacteria. Bacteria
and Cyanobacteria are prokaryotes and they are placed in kingdom Monera.
3. Generally Cyanobacteria are found in moist
places like of trees, rocks and soil, fresh water and oceans.
4. Some of them are symbionts and some are
epiphytes.
5. Cyanobacteria are usually unicellular and
solitary.
NOSTOC
A common example of cyanobacteria which has
filamentous structure which is found in the form a ball is called Nostoc.
Characteristics of Nostoc
The important characteristics of Nostoc are:
1. It has a filamentous structure which form a
ball like structure of Nostoc.
2. It floats on water.
3. Each filament of Nostoc is unbranched and has
a single row of rounded or oval cells.
4. Each cell of Nostoc has double layered wall.
5. The protoplasm is differentiated into two
parts.
6. Endoplasmic reticulum, mitochondria, golgi
bodies and vacuoles are not present in the structure of Nostoc.
7. Heterocyst are found which help in nitrogen
fixation.
8. Nostoc is an autotroph like other
Blue-green-Algae.
Taxonomic Position of Nostoc
According to new classification, Nostoc belongs
to kingdom prokaryota or Monera.
Structure of Nostoc
The structure of Nostoc is filamentous. The
filaments are interring mixed in agelatinuous mass forming a ball like
structure. It floats on water. A single filament looks like a chain of beads.
Each filament is unbranched and has a row of rounded or oval cells.
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Virus, Bacteria and Cyano Bacteria
Friendsmania.net
Micro-Organisms
A large number of living things are present in
this world. Some of them are large and some are small. Majority of the
organisms are so small that they re not seen with naked eyes. For their
observation, we need a light microscope or even an electron microscope. These
microscopic organisms are called micro-organisms.
Micro-organisms As a Heterogeneous Group
Micro-organisms are a heterogeneous group. It
includes different kinds of organism viruses, bacteria, cyanobacteria,
protozoa, certain algae and some fungi. On the basis of structure they range
from sub-cellular to cellular for example, viruses are sub-cellular and all
other micro-organisms are cellular. Bacteria, and cyanobacteria are prokaryotes
(without nucleus) where as algae, fungi and protozoa are eukaryotes (with
nucleus). On the basis of mode of nutrition algae are autotrophic while fungi
and protozoa are heterotrohic. Therefore, micro-organisms differ in their structure
and mode of characteristics of viruses, they are studied in a separate group
where as bacteria and cyanobacteria, being prokaryotes, are included in kingdom
Monera.
Viruses
1. Virus is a Latin word which means
"Poison". Viruses are so small that they can only be seen with
electron microscope.
2. Viruses have charcteristics of both living
and non-living things.
3. Structurally they are not like, cell and are
only made up of proteins and nucleic acids.
4. When they enter the body of any living organisms,
they reproduce there like living organism.
5. They look like non-living crystals when they
are out of the body of a living organism.
6. That is why they are placed between living
and non-living things.
7. All viruses are parasites and cause different
diseases in their hosts.
8. Viruses were discovered by Iwanowsky in 1892
from infected tobacco leaves. In 1935 W.M. Stanley isolated viruses in
crystalline form from infected leaves of tobacco and observed them under
electron microscope.
Size of Virus
Viruses are of different sizes. Their size
varies from 0.01um to 0.03um(um is micrometer = 1/10,00,000 meter)
Shape of Virus
Viruses are of different shapes some are
rounded, few are rod shaped, few polyhedral while some viruses look like
tadpoles.
Structure of Virus
Viruses have same biochemical nature. In spite
of their different shapes, they are made up of only two parts, an outer
"coat", and an inner "core". The core is made up of DNA or
RNA (never both) and the coat is made of protein. The outer protein coat
determines the shape of viruses. e.g. in bacteriophage (virus that lives in
bacteria) protein coat consists of two parts, head and tail. DNA is present in
the head region but the tail has only protein. Most of the animal viruses
contain DNA whereas plant viruses have RNA core bacteriophage is also called
phage virus.
Viral Diseases in Plants
Ring spot in different plants, yellow in sugar
beet and mosaic disease in tobacco, potato, tomato, bean and cabbage are the
various diseases of plants, caused by viruses.
Viral Diseases in Animals
Mouth and foot disease in cattle and cowpox in
horses, buffalo and cows are caused by viruses.
Viral Diseases in Humans
In human beings, viruses produce common cold,
influenza, small pox, yellow fever, polio, infectious hepatitis, cancer and
AIDS.
Ways of Viral Transmission
1. Through droplets produced during coughing and
sneezing.
2. Through contact.
3. By air, contaminated water and food.
4. Through insects.
5. By reuse of already used syringes.
6. By un-sterilized surgery equipments.
Bacteria
Bacteria are found every where in air, water,
living and dead bodies of organisms and even in glaciers and hot springs. These
are unicellular micro-organisms.
Discovery of Bacteria
Leeuwenhoek discovered bacteria in 1697 for the
first time. Later, Louis Pasteur and Robert Koch worked on them. They
discovered that bacteria produce many diseases in men and animals.
Size of Bacteria
Bacteria (singular : bacterium) range from 1um
to 10um in length and from 0.2um to 1um in width and can be observed under
light microscope.
Types of Bacteria
On the basis of shape and form, bacteria are of
four types. These are as follows:
1. Rounded - Cocci (singular; coccus)
2. Rod-like - Bacilli (singular; bacillus)
3. Spiral shaped - Spirilla (singular;
spirillum)
4. Comma like - Vibrios (singular; vibrio)
Bacteria occur both singly and in colonies.
Cocci bacteria are found in groups of two or four, or in irregular groups and
even in the form of long beads. Baccilli are found singly or may join end to
end to form long threads. But Spirilla and Vibrios occur singly.
(Diagram)
Structure of Bacteria
1. Bacteria are single celled prokaryotic
organisms.
2. Bacterial cell is surrounded by a cell wall
which is made of carbohydrates and amino acids.
3. Some bacteria have an additional slime
capsule around their cell wall, which protects them and prevents them from
drying.
4. Ribosomes help in synthesis of proteins.
Nucleus is absent in bacterium. However, only a single large circular molecule
of DNA is present which is surrounded by a clear zone of cytoplasm. It is known
as nucleoid. This is not bounded by a nuclear membrane.
5. In addition to main bacterial DNA small,
circular molecules of DNA called plasmids are also found. Plasmids play an
important role in transmission of some heredity characteristics. Plasmids are
also used a vectors in genetic engineering.
6. Motile (which can move) bacteria like bacilli
are spirilla have one or more thread like flagella (singular; flagellum) which
help them in their locomotion. Non motile bacteria like cocci lack flagella.
Economic Importance of Bacteria
It is generally thought that bacteria are fatal
and harmful organisms and there is no beneficial aspect. But this is wrong
impression. There are number of bacteria which are not only beneficial for
mankind but are also essential for living system. Bacteria play very important
role in the life of living organisms.
Beneficial Bacteria
Ecological Importance
These, along with fungi, help to decompose dead
organisms and their refuse into simpler substances replenishing the raw
materials in the soil and atmosphere and can thus purify the environment.
Bacteria and Nitrogenous Compounds in Soil
These bacteria are called nitrogen fixing bacteria.
Another kind of bacteria live in the soil, called nitrifying bacteria which
convert ammonia into nitrite and then to nitrate, enhancing the amount of
nitrogen in the soil. In this way fertility of soil is increased.
Industrial and Commercial Purposes
1. These are used in manufacturing butter,
cheese and yogurt.
2. These are used in processing of commercial
fibers, leather, coffee, tobacco and vinegar.
Bacteria Synthesize Enzymes
Bacteria synthesize cellulose enzyme in the
stomach of herbivore animals which helps in the digestion of food. Some
bacteria also synthesize vitamin "B" and "K" in the large
intestine of man and other mammals.
Bacteria as Bio-Insecticides
Recently the use of bacteria in bio-insecticides
has become popular.
Harmful Bacteria
1. Bacterial decomposition on one hand is
beneficial but on other hand causes damage to food, wood, clothes and other
things.
2. Denitrifying bacteria in soil decrease the
amount of nitrogen in soil and reduce the soil fertility. These are called
identifying bacteria.
3. Many bacteria are harmful and cause many
diseases in plants, such as canker disease in citrus fruits, rot and fire
blight in peach, pear and apple, and potato scab in potato.
4. In animal like cattle bacteria cause T.B and
anthrax. Bacteria also cause many diseases in man like T.B, Whooping Cough,
Diphtheria, Typhoid, Pneumonia, Tetanus, Plague, Bacterial Dysentery, Cholera,
Leprosy etc.
Ways of Bacteria Transmission
1. Whooping cough, Diphtheria, T.B and Pneumonia
causing bacteria are transmitted from one person to other person through
sneezes and cough droplets released in air.
2. Bacteria causing Typhoid and Cholera, are
transmitted from one organism to another through contaminated water and food.
3. Plague and bacterial dysentery read through
vectors like flies and animals.
Cyanobacteria
1. Cyanobacteria are also called blue green
algae. They are simplest living organisms which have the ability to manufacture
their own food by photosynthesis.
2. Structurally they resemble bacteria. Bacteria
and Cyanobacteria are prokaryotes and they are placed in kingdom Monera.
3. Generally Cyanobacteria are found in moist
places like of trees, rocks and soil, fresh water and oceans.
4. Some of them are symbionts and some are
epiphytes.
5. Cyanobacteria are usually unicellular and
solitary.
NOSTOC
A common example of cyanobacteria which has
filamentous structure which is found in the form a ball is called Nostoc.
Characteristics of Nostoc
The important characteristics of Nostoc are:
1. It has a filamentous structure which form a
ball like structure of Nostoc.
2. It floats on water.
3. Each filament of Nostoc is unbranched and has
a single row of rounded or oval cells.
4. Each cell of Nostoc has double layered wall.
5. The protoplasm is differentiated into two
parts.
6. Endoplasmic reticulum, mitochondria, golgi
bodies and vacuoles are not present in the structure of Nostoc.
7. Heterocyst are found which help in nitrogen
fixation.
8. Nostoc is an autotroph like other Blue-green-Algae.
Taxonomic Position of Nostoc
According to new classification, Nostoc belongs
to kingdom prokaryota or Monera.
Structure of Nostoc
The structure of Nostoc is filamentous. The
filaments are interring mixed in agelatinuous mass forming a ball like
structure. It floats on water. A single filament looks like a chain of beads.
Each filament is unbranched and has a row of rounded or oval cells.
Bryophytes
and Tracheophytes
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Bryophytes
Bryophytes are on of the two main groups of
kingdom 'Plantae' the second being the 'tracheophytes'. Bryophytes is a group
of plants which are multicellular, photosynthetic eukaryotes; and their
reproductive organs are multicellular; their zygote develops into small,
protected embryo that develops into a complete new hence bryophytes have also
been called embryophytes. The cell of these plants is made up to cellulose.
Characteristics of Bryophytes
The important characteristics of Bryophytes are
as follows:
1. Bryophytes are plants without vascular tissue
(xylem a phloem), whereas tracheophytes have vascular tissue. Therefore
tracheophytes are vascular plants, whereas bryophytes are non-vascular plants.
2. Bryophytes are the simplest land plants.
Bryophytes divided into three groups. Liverworts, hornworts, and mosses.
3. Marchantia is an example of liverworts; its
plant body is a thick branched green thallus.
4. Anthoceros is a horn wort, and Funaria is a
moss.
5. All bryophytes and generally found growing in
moist habitants such as damp soil and rocks, moist brick walls, and along the
banks of streams.
Life Cycle of Funaria Moss
It is a common moss found grwoing t moist
places. Green leafy, moss plant of Furania, as like all Bryophytes, Funaria is
haploid gametophyte, its height is about 0.5 - 1 inch.
(Diagram)
Gamatophyte Generation
It consists of 3 parts:
1. A vertical stem like structure.
2. Leaf like photosynthetic structures arranged
on the stem, which are composed of a single layer of cells, and without stalk.
3. Numerous multicellular rhizoids, arising from
the lower side of the stem and which absorb water and salts, and anchor the
plant to the soil.
Male sex organs, called antheridia (singular
antheridium) are located at the tip of male branch, and the female sex organs,
called archegonia (singular archegonium) are located at the tip of female
branch.
Fertilization takes place in the presence of
water within the archegonium located at the tip of female branch. The zygote
develops into the embryo (2n). The embryo forms the sporophyte (2n). The
sporophyte remains attached to the tip of female branch. The sporophyte gets
water, slts and also part of its food, from the parent gametophyte plant.
Sporophyte Generation
The sporophyte consists of three parts:
1. A foot
2. A long stalk like seta
3. Capsule
The foot is anchored to the female branch and
absorbs nutrients from the gametophyte. The seta elevates the capsule in the
air. Within the capsule, haploid spores are produced by meiosis. The spores are
dispersed by wind. Each spore develops eventually into new haploid gametophyte
plant, and the life cycle continues.
Like other bryophytes, Funaria also has well
defined alteration of generations; haploid gametophyte generation is dominant,
whereas diploid sporophyte is attached to and more or less dependent on the
gametophyte.
Pteridophytes
1. Unlike bryophytes the plant body in
Pteridophytes is differentiated into root, stem and leaves.
2. In contrast to other vscular plants
Pteridophytes do not bear flowers, fruits and seeds.
3. Due to presence of vascular tissues, they are
similar to gymnosperms and angiosperms.
4. Although the dominant generation in
Pteridophytes is also the sporophyte but unlike gymnosperms and angiosperms
both sporophyte and gametophyte generations are independent and free living.
However, the gametophyte in much reduced and smaller in size.
Spermatophytes
Seed plants or Spermatophytes are that group of
vascular plants which produce seeds. Seed is a ripened ovule. It contains a
young plant with embryonic root, stem and one or more leaves, which has stored
food material and is protected by a resistant seed coat or testa.
Spermatophytes like pteridophytes possess
vascular tissues. They also have life cycles with alternation of generations.
Unlike bryophytes and pteridophytes, spermatophytes do not have free living
gametophyte; instead the gametophyte is attached to and nutritionally dependend
upon the sporophyte generation.
Main Groups of Spermatophytes
Gymnosperms
They produce seeds which are totally exposed or
borne on the scales of cones.
Angiosperms
They are flowering plants which produce their
seeds within a fruit.
Pinus and Thuja - The Typical Gymnosperm
Pinus is normally grows at an altitude of 5000
ft to 8000 ft. It has many types e.g. chir, kail, chilghoza etc. However, some
species are found in the plains. It is also grown as ornamental plants. Pinus
tree is a sporophyte, which is evergreen and quite tall. It consists of an
extensive root system and a strong, stout and woody stem and its branches. The
upper branches progressively become shorter in length. In this way, the tree
assumes a symmetrical conical shape.
(Diagram)
Thuja
Thuja (common known as Mor Pankh) is a short
tree. It has profuse branches, which are covered with small, dark green scale
leaves. It is conical in appearance. It is grown as ornamental plant in parks
and homes.
Leaves of Thuja
Thuja has small scale like green leaves that
cover the stem.
Female Cone of Thuja
In Thuja the female cones are spherical or oval in
shape. These are about the size of a bair (berry). They consist of hard, brown
colour scales with triangular apices.
Pinus
Pinus has two types of shoots.
Shoots of Pinus
Long Shoots or Shoots of Unlimited Growth
They are formed on the main stem and continue
growth indefinitely by buds borne at their apices. They are covered by scale
leaves.
Dwarf Shoots or Shoots of Limited Growth
These shoots originate in the axils of the scale
leaves on the long shoots. They are very short (only a few millimeters in
length). Each dwarf shoot bears 1 t 5 foliage leaves in addition to scales
leaves.
Leaves of Pinus
Scale Leaves
These are small, membranous and brown in colour.
They cover the stem.
Foliage Leaves or Needles
These are commonly long and narrow, tough, and
leathery. In contrast to scale leaves they are green and photosynthetic.
Depending upon the type of species, a cluster of 2 to 5 needles is produced on
each dwarf shoot. Each dwarf shoot with its cluster of needles is called a
spur.
Reproduction in Pinus
Pinus tree produces reproductive structures
known as cones every year. Cones are of two types, male and female c9ones. Both
male and female cones are produced on the same tree but on different branches.
Male Cone of Pinus
Male cones, usually 1 cm or less in length, are
much smaller than the female cones. They are produced in clusters. These are
generally born on the lower branches of the tree. Each male cone is composed of
spirally arranged leaf-like structures called scales or microsporophylls. Each
microsporophyll has two long sacs called pollen sacs of microsporangia on it
are under surface. Asexual reproductive cells, microspores or pollen grains are
produced by meiosis in the microsporangia. Pollen grains are haploid. After
being transferred to the ovule, the pollen grain forms pollen tube. It is the
male gametophyte in which male gametes or sperms are produced.
Female Cone of Pinus
The female cones are much larger than the male
cones. These are usually found on the upper branches. Each female cone is also
made of spirally arranged scales which are called megasporophylls. These scales
become woody on maturity. Two ovules are present side by side at the base of
each scale. Haploid megaspores are formed in the ovule by meiosis. Measpores
give rise to female gametophytes which produce female gametes. Fertilization
results in the formation of embryo after which the ovule is ripened to form
seed. Female cones normally remain attached for three years on the plant. On
maturity the cones open up and the seeds are set free and dispersed.
Angiosperms
Angiosperms are the flowering plants which are
most successful plants. They are more important than the gymnosperms. They have
adapted to almost every type of environment. There are about at least 235,000
species. They are dominant plants. Angiosperms are vascular plants which bear
flowers. Their seeds are produced within fruits. The fruit protects the
developing seeds and also helps in their dispersal. Seed and fruit producing
habit have helped flowering plants in their evolutionary success.
Angiosperms are found in wide variety of sizes
and forms. Ensize they range from over 300 ft in height (some species of
Eucalyptus) to searcely 1mm in length (duckweed, Woiffia).
On the basis of size and woody texture,
angiosperms are classified as herbs, shrubs (bushes) and trees. Herbs are the
plants which are small in size. Their stems are Herbs which are then cut or
pulled from the soil. In contrast shrubs and trees have hard woody stems, which
retain their shape even after being cut. Shrubs are shorter than trees but have
more branches. In addition to tracheids, angiosperms have efficient water
conducting structures known as vessels in their xylem.
Classes of Angiosperms
On the basis of the number of cotyledons in the
seed, angiosperms are divided, into two classes.
1. Monocotyledons or Monocots
2. Dicotyledons or Dicots
Monocots
1. Monocot seeds have only one cotyledon or
embryonic leaf.
2. A nutritive tissue called
"endosperm" is usually present in the mature seed.
3. Monocots are mostly herbs with long narrow
leaves.
4. Leaves have parallel veins i.e. in the lamina
of the leaf veins run parallel to one another.
5. The floral parts of most flow3ers usually
occur in threes or multiples of three (i.e. 3, 6, 9 ...)
6. Monocots include different grasses, cereals
(wheat rice, maize etc) ,palms, onions and lilies.
Dicots
1. Dicot seeds have two cotyledons.
2. In mature seed, te endosperms is usually
absent.
3. Their leaves vary in shape but usually are
broader than monocot leaves.
4. Leaves have reticulate veins i.e. branched
veins resembling a net. The flower parts are four or five in number or
multiples of 4 or 5.
5. Dicots include rose, peas and pulses,
sheesham, Kiikar (Acacia), sarsoon (mustard), cacti, mango, orange and
sunflower etc
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Invertebrata
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Protozoa
1. According to two-kingdom classification,
protozoa are the first phylum of invertebrate animals but according to five
kingdom classification it is placed in a separate kingdom, "protista"
in which all other eukaryotic unicellular organisms are also placed.
2. Body of all protozoans consists of one cell
and istherefore called unicellular.
3. They are so small in size that they cannot be
seen with naked eye. They can be seen with the help of a microscope.
4. They are unicellular but they intake food,
respire, reproduce.
5. Protozoans mostly live in damp, watery
places. Their habitat is mostly moist soil, decaying matter of animals and
plants. Most of them live singly but some form colonies. In a colony,
unicellular organisms become partially interdependent and limit themselves to
perform specific functions in a group. If separated from group they still can
perform all life activities and can live independently.
6. Some protozoans are parasites and causes
different diseases e.g. a type of Amoeba causes dysentery, plasmodium causes
malaria.
7. Protozoans are also useful for man because
they feed and destroy bacteria which are harmful for human health, for example
Amoeba can feed on bacteria.
Paramecium
It is unicellular animal which is found in pools
and ponds. It is slipper shaped its body is covered with cilia. Cilia are small
hair like out structures arising from protoplasm. Their lashing movement in
water acts as oars and help in swimming (locomotion) of the animal. Paramecium
feed on algae. Bacteria and other small protozoans, through an oral groove
provided with cilia. Cilia push food inside the protoplasm through a canal
called gullet making a food vacuole in the protoplasm. There are two
contractile vacuoles, one at each end of the body for discharging surplus water
there are two nuclei one large, mega nucleus which controls almost all
functions of cell other small, micro or reproductive nucleus which controls
reproduction. Many protozoa like Amoeba and Paramecium are unicellular but they
respond to the intensity of light like all other multicellular organisms. They
can detect high intensity of light and move towards the area having low
intensity of light.
Phylum Porifera
1. This phylum is called porifera because
animals belonging to this phylum have numerous small pores on their bodies.
2. They are also called sponges.
3. They are multicellular but they have no
organs or true tissues.
4. Every cell performs its all function.
5. Sponges are aquatic animals. Most of them are
found in sea water but some live in fresh water.
6. Sponges have different colours.
7. Green colour of sponge is due to algae that
live in their body. Algae produce oxygen during photosynthesis which is used by
sponges and the sponges release carbondioxide, which is used by algae for
photosynthesis. This association in which both the organisms benefit from each
other is called mutualism.
Phylum Cnidaria
1. Animals belonging to this phylum have a
special cavity in their body which is called coelenteron and due to this reason
they are called coelenterates.
2. They are diploblastic animals as their bodies
have two layers of cells. Outer layer is called ectoderm and inner layer is
called endoderm. Between these layers a jelly like substance the mesoglea is
present.
3. Coelentrates are aquatic animals. They are
mostly marine but few live in fresh water.
4. Most of the animals of this phylum can move
freely but a few remain attached to stones or rocks throughout their life.
5. Hydra, Jellyfish and Sea anemone are common
examples of this phylum.
Phylum Platyhelminthes
They are triploblastic animals because their
body is made of three layers, an outer ectoderm, a middle mesoderm and an inner
endoderm layer. They are also called flat worms because their body is thin,
flattened and tape like. Some animals are free living but most are parasite.
Parasites live in liver, stomach and intestine of other animals. They attach
themselves to the walls of intestine of their host by sucker and suck blood and
food. Tape worm sucks food from intestine and sometimes grows up to 40 feet in
length. Liver fluke, tape worm and planaria are common examples of this phylum.
Phylum Mollusca
1. This phylum is one of the largest phyla of
animal kingdom. It has about fifty thousand species.
2. Mollusca are a latin word which means
"soft". Their body is soft so in most of the animals and external
shell is present for support and protection.
3. Some animals have internal shell and some
lack shell. They are also known as shell fish.
4. They are found in aquatic and moist habitat.
5. Most of Mollusca are used as human food.
6. Buttons are made from their shell.
7. The pearls are produced by these animals.
8. Their body is quite complicated.
9. They have a muscular foot for locomotion and
gills for respiration.
10. Snails, Fresh water mussel, Cuttle fish,
Octopus and Oyster are common examples of this phylum.
Phylum Arthropoda
1. The bodies of these animals are also
segmented but these segments are external.
2. Their bodies are covered with the hard shell
composed of chitin, forming an exoskeleton.
3. They have jointed legs on their body and
therefore they are called arthropoda (arthro means jointed and poda means foot)
4. These animals are found in all habitats, in
air, water and on land.
5. Common examples are Prawn, Crab, Spider,
Scorpion, Centipede, Millipede and Insects.
Phylum Echinodermata
1. The animals of this phylum are exclusively
marine.
2. They are called echinoderms because their
bodies are covered with spines or spicules.
3. All animals have internal skeleton consisting
of dermal caleareous ossicles.
4. They have a water vascular system and dermal
gills.
5. These animals are considered to be closest to
the chordates from evolutionary point of view, Sea star (known as star fish).
Brittle star, Sea urchin and Sea cucumber are examples of this phylum.
Phylum Annelida
1. Animals in this group have elongated
segmental body.
2. Annelids occur in water as well as on land.
3. They have well developed systems in their
bodies.
4. They have close type circulatory system.
Phylum Nematode
1. Nematodes or round worms have long smooth
cylindrical body which is pointed at both the ends.
2. The body is un-segmented.
3. Nematodes have a complete and one way
digested tube.
4. They are free-living as well as parasites of
animals, man and even plants
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Chordata
and Vertebrata
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Characters of Class Pisces (fishes)
1. The class of fishes is called Pisces. They
are aquatic vertebrates.
2. According to their size and shape, the fishes
are of many kinds.
3. They have a head, a trunk and a tail.
4. The head and trunk are directly jointed
together and neck absent.
5. Body of fish is flexible tapering at both
ends and streamlined. This type of body helps in swimming.
6. They can swim with fins, which are attached
to the trunk.
7. They body is covered with scales which remain
moist by special type of secretion of body.
8. Breathing organs are gills which are present
in the hollow spaces found on both sides of the head for exchange of gases i.e.
oxygen and carbon dioxide.
9. Mouth has teeth, which is used for grasping
instead of grinding of food.
10. In some fishes air pouch is present, which
is called air bladder. The air bladder is used for buoyancy.
Class Amphibia
1. This group of animals can live both in water
and on land.
2. They need water for reproduction. Therefore
they are called Amphibians.
3. The skin is thin, moist and slimy.
4. Small teeth are present in the upper jaw
which is only used for grasping the prey.
5. Breathing organs are two lungs. Skin is also
used for the exchange of gases.
6. Eggs are laid in water or moist places and
their outer shells are not hard.
7. They are cold blooded animals e.g. they
cannot maintain their body temperature constant.
8. They become very slow and bury themselves in
the mud. This process is called hibernation.
9. During the process of reproduction fertilized
egg is changed into adult passing through a number of physical changes. This
process is called metamorphosis.
10. The fertilized egg develops into larva. The
larva of frog is called Tadpole. It has tail and gills. This larva later
changes into adult.
Class Reptilia
The animals of this class are called reptiles.
They have following features.
Reptiles
1. Most of the reptiles are terrestrial and only
a few five in water.
2. They are also called crawlers.
3. They have thick, dry and rough skin.
4. The skin is covered with scales which
originate from the ectoderm.
5. There are present lungs for respiration.
6. Teeth are present in their buccal cavity,
which are used for cutting and biting.
7. The locomotary organs are legs but snakes and
a few types of lizards have no legs.
8. Most of the lizards are not poisonous except
members of the genus Heloderma which are found in American desert.
9. All the reptiles lay their eggs on land.
Water dwelling reptiles e.g. turtle also lay their eggs on land.
10. Their eggs have a tough outer shell of
calcium carbonate.
Class Aves
The animals included in this class are called
Birds. Their distinguishing characters are as follows.
1. Birds have a single unique feature, which
makes them different from other animals which is the presence of feathers.
Their forelimbs are modified to form wings while hind limbs help in walking,
wading and sitting on the branches.
2. All the birds have horny beaks without teeth.
3. All the birds lay eggs.
4. All the birds must have two wings for support
and propulsion, strong but light and hollow bones.
5. Their digestive system is able to digest high
caloric food.
6. They have a higher blood pressure and higher
metabolic rate.
7. Nervous system and especially eye sight is
very well developed so that they can track their path even at a very high
speed.
8. They migrate during winters towards warmer
places covering thousands of miles.
9. It is the most studied and most observable
class in the world.
10. The birds are very beautiful and have
melodious voices.
Types or Groups of Birds
Running Birds (Ratitae)
They have following characters:
1. They have flattened sternum.
2. Their pectoral muscles are weak.
3. Their examples are Ostrich, Emu, Rhea and
Casso wary.
Flying Birds (Carinatae)
They have following characters:
1. A keel is present on sternum in these birds.
2. Keel is vertical bony part that is present
below the sternum in the centre from anterior to posterior end.
3. Pectoral muscles are very strong, powerful
and are inserted on the keel. These muscles help them to fly.
4. Their common examples are pigeon, hen, crow,
kite etc.
Class Mammalia
All the animals included in this class are
called "mammals". These animals are highly advanced vertebrates.
There are almost four thousand species of mammals including man.
Characteristics of Mammals
Their distinguishing characters are given below:
Hair
The body of mammals is covered with hair. In
most of the mammals hair may cover the whole body but in a few may be
restricted to some areas. The hair conserves heat of the body.
Glands
Their skin is provided with sweet glands, scent
glands, sebaccous glands and mammary glands.
Skeleton
Two occipital condyles, secondary bony palate,
three bones in middle ear and fused pelvic bones and seven cervical vertebrae
are present in their skeleton.
External Ear
Fleshy external ears are present in mammals.
Eyelids
Moveable eyelids are present in mammals.
Teeth
Two sets of teeth are present. Milk teeth are
replaced by permanent set of teeth.
Brain
Brain is higly developed. It perform more
functions than that of other vertebrates.
Cranial Nerves
Twelve pairs of cranial nerves are present.
Circulatory System
Circulatory system has four chambered heart,
persistent left aorta and non-nucleated biconcave red blood corpuscles are
present in female.
Sexes
Sexes are separate i.e. there are two individuals,
male and female.
Fertilization
Most of them have internal fertilization and
fetus developed inside the uterus of female giving birth to their children.
Breast Feeding
They feed the children by milk from mammary
glands.
Endothermic
They are endothermic i.e. they can maintain
their body temperature according to the environment. It means that they are
warm-blooded animals.
Egg Laying Mammals
These mammals lay eggs. Mostly two eggs are laid
in one year. Fertilization of egg is internal i.e. inside the body of mother.
Eggs are laid in burrows of animals. Young ones are hatched from the eggs.
Mother feed their children with milk. Their egg laying character shows their
relationship with reptiles. Duck bill platypus and Spiny ant eater are the examples
of egg laying mammals.
Pouched Mammals or Marsupial Mammals
These mammals have a pouch outside the belly
called marsupium, this is the reason that they are also known as Marsupial
mammals.
1. Fertilization of eggs and development of
embryo is internal.
2. The embryo is at first encapsulated by shell
membrane and floats free for several days in the uterine fluid.
3. There is no placenta.
4. After hatching from the shell membranes, the
embryo does not implant or "take root" in the uterus and absorb
nutrient secretions from the vascularized yolk sac.
5. The gestation period is brief and the
marsupials give birth to tiny young that is effectively still an embryo.
6. These young creeps into the marsupium where
it gets milk from mother through nipple.
7. It lives in marsupium until it can take care
of itself.
8. Examples are Kangaroo, Koala, Tasmanian wolf
and Wombat etc. These are found in Australia and Tasmania, Opossum is found in
America. It lives on trees.
Placental Mammals
This is common group of mammals in which embryo
completes its development inside the mother's uterus. After gestation period
young ones are born. Embryo remains in the uterus and gets its nourishment from
mother through umbilical cord and placenta. Gestation period of these mammals
is longer than those of other mammals. Pregnancy is called Gestation Period. In
man it is of 9th months.
In mice it is 21 days, in rabbit 30 to 36 days,
in cats and dogs 60 days, in cattle 250 days and in elephants 22 months. It is
lengthier in large mammals.
The conditions of young ones at time of birth
are different in different mammals. For example in antelope, at the time of
birth, the body of young is covered over, with heavy fur, eyes are open and it
can walk about. In case of rat, young is very weak, eyes are closed and has no
hair on the body.
Flora and Fauna of Pakistan
Flora
Definition
"Different types of plans present in a particular region constitute
its flora."
Details
1. Hilly regions of Pakistan have snow fall and
low temperature. These regions have thick forests where trees of Juniper
(Sanober), Cedar, Chir, Chalghoza, Olive Apple, Plum Peach and Loqaut are very
common.
2. Plain areas of Pakistan have fertile and less
fertile soils. In areas where rainfall is low, desert environment is present in
which Aeacia (Babool), Kikar, Ber, Pilas etc grow.
3. Fertile plains have trees of Sheesham,
Bakain, Cane, Bamboo and Eucalyptus. These are source of timber whereas; fruit
trees include mango, banana, Kino, Orange, Grapes, Jamman etc.
4. Plain and hilly areas have natural pasture
lands that provide fodder for cattle.
5. In sea, rivers, ponds, canals and streams,
algae are abundant, which on one hand are the source of food for aquatic
animals and on the other hand they provide oxygen to atmosphere.
6. A large number of plants are used as
ornamental plants. These include flowering plants like rose, motia, jasmine,
lady of night, chrysanthemum etc.
7. Besides this wheat, maize, rice, oats,
burley, grams garlic, onion, potatoes, carrots, cabbage and turnips etc are
cultivated in plains and hilly areas to meet our food requirements.
Fauna
Definition
"Different kinds of animals present in a particular region are known
as its Fauna."
Detail
1. In the seas adjoining our coastal areas
numerous types of animals are found starting from protozoa to mammals. The most
noticeable are octopus, mussels, star fish, sea urchins, crabs, prawns, fishes,
amphibians, whale, dolphin etc.
2. Many animals are used as food e.g. prawns,
crabs and fish etc. Our rivers are rich in fish life particularly Rohu, Khagga,
Malhi, Trout, and carps are abundant and used as human food, as well as a
source of earning lively hood.
3. Frogs and toads are abundant.
4. The tortoises, turtles, snakes, crocodiles
are also common.
5. On the plains of Pakistan we have very rich
wild life. There is a great diversity of land fauna starting from earthworms,
almost all kinds of insects, spiders, myriapods, snails, slugs to toads,
lizards, snakes and enormous variety of birds and mammals.
6. Some of the birds peculiar to Pakistan are
Houbara bustard, partridge, pheasant, falcons etc.
7. The mammals peculiar to Pakistan include
Black buck, Blue ball, Brown bear, Musk deer, Urial, Ibex, Asiatic ass.etc.
8. Most of the animals provide milk, meat, hide
and wool. Some are used for transportation. Some of the animals are now
endemgered species because of their excessive hunting and pollution.
WARM BLOODED ANIMALS
The animals which do not change their body
temperature with the change of temperature in environment are called as Warm
Blooded Animals. Their body temperature remains constant.
Example
Common examples of warm blooded animals are
following.
(i) Parrot
(ii) Sparrow
(iii) Pigeon
(iv) Ostrich
(v) Kiwi
(vi) Duck billed platypus
(vii) Kangaro
(viii) Oppossum
(ix) Elephant
(x) Whale
(xi) Monkey
(xii) Man
COLD BLOODED ANIMALS
The animals in which the body temperature is
changed with the changes of temperature in the environment are called Cold
Blooded Animals.
Example
Common example of cold blooded animals are
following.
(i) Shark
(ii) Labeo (Rohu)
(iii) Trout
(iv) Hilsa (Pullah Fish)
(v) Cat Fish (Khagga)
(vi) Frog
(vii) Toad
(viii) Snake
(ix) Wall-Lizard
(x) Crocodile
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Light
and Dark Reactions
Friendsmania.net Light Reactions
When light falls on the leaves, it is absorbed
by chlorophyll. The solar energy is used to split water into oxygen and
hydrogen and this is called photolysis (photo means light and lysis means to
break). The oxygen is released into the atmosphere as by-product of
photosynthesis. As this process takes place only in the presence of light, it
is called light reaction.
During light reaction, two compounds are formed
when the solar energy is converted into chemical energy these are:
1. NADPH (Nicotinamide Adenine Dinucleotide
Phosphate)
2. ATP (Adenosine Triphosphate)
NADP, already exists in the cells of the leaf.
The hydrogen released on the splitting of water molecule is accepted by this
compound and it is reduced to NADPH.
ADP (Adenosine Diphosphate) is already present
in the cell; it combines with the phosphate group using light energy to form a
compound called ATP.
These compounds are energy rich compounds which
are needed for the dark reactions of the process. Light reaction is called high
dependent reaction.
(Diagram)
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Dark Reactions
Using the energy of ATP and the NADPH, water
combines with carbon dioxide to form carbohydrate. Thus the solar energy is now
converted into chemical energy to form glucose. Other organic compounds are
also synthesized from this glucose.
This stage is completed in a series of chemical
reactions with the help of enzymes. Neither light energy nor chlorophyll is
needed for dark reactions. Therefore dark reaction is also called light
independent reaction.
Various steps of the dark reactions were studied
by a scientist called Melvin Calvin so the dark reaction is also called the
Calvin's Cycle.
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Definition
of Enzymes
Enzymes are chemical compounds. They are protein
in nature. They are formed in living cells. They are not consumed in a reaction
but act as a catalyst as they only speed up the chemical reactions.
Types of Enzymes
There are two types of enzymes:
1. Intracellular Enzymes
2. Extracellular Enzymes
Intracellular Enzymes
They work within a cell, in which they are
produced.
Extracellular Enzymes
Some enzymes are secreted out of the cells where
they work. They are called extracellular enzyme. Bacteria and fungi secrete
such extra cellular enzymes into the medium in which they are growing. The
higher organisms secrete extracellular enzymes into the lumen of alimentary
canal to act on the food.
The enzymes acting on the starch are known as
Amylases; those acting on proteins are known as Proteinases, while those acting
on fats are known as Lipases.
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Characteristics of Enzymes
The characteristics of enzymes are as follows:
1. All enzymes are protein in nature; they can
be destroyed by heating.
2. They act best within a narrow, temperature
range.
3. They work efficiently in narrow range of
acidity or alkalinity.
4. A particular enzyme forms the same
end-product, because it acts on a particular/specific substrate.
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Digestion
of Food
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First of all food comes in the oral cavity where
the teeth crush and break the food and convert it into small particles. The
tongue rolls the morsel of food and pushes it under teeth again and again so
that the food is evenly divided into fine particles and the saliva secreted
from the salivary glands gets mixed with the food. The saliva lubricates the
food and makes the particles adhere to one another, forming a ball of food
called bolus. Now the chemical digestion of food begins. Saliva contains an
enzyme to digest starch in the food. The combined action of teeth, tongue and
saliva pushes the bolus through the throat into the oesophagus, and then it
reaches the stomach.
Definition of Digestion
Digestion is the process in which the insoluble
and non-diffusible components of food are broken down and by the action of
enzymes are converted into soluble and diffusible substance to be absorbed into
the blood stream.
Types of Digestion
1. Mechanical digestion
2. Chemical Digestion
Mechanical Digestion
In mechanical digestion, the food consisting of
large sized particle is broken into fine pieces by cutting, grinding, chewing
and churning up, so that enzymes can act upon it efficiently and effectively.
Mechanical digestion of food takes place in the mouth and stomach.
Chemical Digestion
In chemical digestion, the digestive enzymes mix
with the food and act upon it to break it down further into simple and
diffusible chemical forms. The enzymes act on carbohydrates, proteins and fats
separately. Chemical digestion takes place in all the major parts of the
digestive system. The digestive glands such as liver and pancreas also play
very important role in this digestion.
Digestive System
All living things require food to live and carry
on their life functions. Animals are unable to synthesize their food.
Digestion is the process in which the
non-diffusible molecules of food are changed to diffusible ones by the action
of enzymes. All the organs which take part in this process make a system which
is called the digestive system.
Human Digestive System
The process of digestion takes place in the
alimentary canal. It starts from the mouth and ends at the anus. The tube
assumes different shapes according to their role in the process of digestion.
It consists of the mouth, oesophagus, stomach, small intestine, and large
intestine. Besides these organs liver and pancreas, also play important roles
in digestion.
Peristalsis
The muscles of alimentary canal produce rhythmic
waves of contraction which is called peristalsis. Due to this process, food is
carried through various parts of the alimentary canal.
Ingestion
The food of animals and human is in the solid
form and may be bulky. Taking in of the food in the oral cavity and swallowing
is called ingestion.
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Digestion of Food in the Mouth
During mastication, the food is mixed thorougly
with the saliva while the food is in the oral cavity (buccal cavity). The
saliva is secreted by three pairs of salivary glands located in the buccal
cavity. The saliva is continuously secreted by the salivary glands in response
to the presence of food in the buccal cavity.
Saliva is alkaline and contains an enzyme
ptyalin. This enzyme converts starch into sugar (maltose). The morsel of food
after being chewed and thoroughly mixed with the saliva is called a bolus. It
is rolled down by the swallowing action into the oesophagus which conveys it to
the stomach by the wave of peristalsis. The end of stomach lined with
oesophagus is called cardiac end.
Digestion of Food in the Stomach
Stomach is a thick sac like structure, in which
food is stored for some time. Its wall is strong and muscular. Its inner
surface has numerous glands called gastric glands. These glands secrete a juice
called gastric juice. Human stomach secretes about one to two liters of this
juice daily; Gastric juice contains Hydrochloric acid and two enzymes, renin
and pepsin. Hydrochlroic acid changes the medium of food to acidic. This medium
kills the bacteria that may be found in the food. the pepsin acts on proteins
and breaks them down into peptones. Renin helps to curdle milk in infants.
There is no chemical action on carbohydrates and fats present in food. the
regular movements of the stomach churn up the food. the food is changed into a
thick fluid called chyme. When digestion in the stomach is complete, the distal
end of the stomach called the pyloric end relaxes, and allows a small amount of
chyme to pass into the first part of the small intestine. Food stays in stomach
for about 2-3 or 3-4 hours.
Digestion of Food in the Small Intestine
Food from stomach enters the duodenum which is
the first part of the small intestine. An alkaline pancreatic juice from the
pancreas and bile juice from the liver and poured into the duodenum by a common
duct. Both the juices contain bicarbonates which neutralize the acidic chyme
and make. It rather alkaline besides these juices other intestinal juices from
the walls of the small intestine are also poured. These entire juices act on
food and help in digestion of food.
Liver
It is largest gland, in the body. Its colour is
reddish brown. It lies just below the diaphragm on the right side of the body
under the ribs. It has five lobes, three on the right side and two on the left.
The cells of the liver secrete a greenish yellow alkaline fluid which is called
the bile juice. It contains bile salts and bile pigments which give greenish
yellow colour to the juice. Bile contains no digestive enzymes, but it does
contain bile salts which break down the large molecules of fats to small fat
droplets. This process is called emulsification. This process helps in the
digestion of fats. Bile juice also contains bile pigments that are by products
of red blood cells, these pigments are eliminated from the body along with the
faeces, and the colour of faeces is due to these pigments. Besides this, bile
juice also kill the germs in the food.
Functions of Liver
1. Liver stores glycogen and regulates the level
of glucose in the blood.
2. It breaks down excess amino acids. this
process is called deamination.
3. It is involved in detoxification.
4. It produces and secretes bile juice which is
stored in the gall bladder.
5. It metabolizes carbohydrates, fats, proteins
and other compounds.
6. As a result of chemical changes a lot of heat
is produced, therefore liver helps to keep the body warm.
7. It makes fibrinogen and other blood proteins.
8. It decomposes the damaged red blood cells.
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Pancreas
It is a leaf like organ. It lies below the
stomach and between the two arms of duodenum. The pancreas produces a juice
which is called the pancreatic juice. This juice flows down the pancreatic duct
into the duodenum. It contains three enzymes.
1. Pancreatic amylase which acts on undigested
starches of the food and converts them into maltose.
2. Enzyme trypsin which breaks down proteins
into peptides.
3. Lipase which splits fats into fatty acids and
glycerol.
If any of the constituents of food still remain
undigested, enzymes secreted by the glands in the small intestine act upon them
and complete the digestion by converting peptides to amino acids, maltose and
other sugars to glucose and fats to fatty acids and glycerol.
The enzymes secreted by the intestinal walls are
amino-peptidases and disaccharidase,(which form glucose from maltose, lactose
and sucrose). In this way food is completely digested at intestine
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Teeth
God has blessed animals and human beings with
teeth. They help in breaking and chewing of the food. They are present in oral
cavity.Teeth are attached to the upper and lower jaws.
Kinds of Teeth
Humans have two sets of teeth during their
lives.
Milk Teeth
The first set of teeth begins to come through
the gums when the baby is about six months old. these are called the milk teeth
and all twenty teeth are formed over a period of two years.
Permanent Teeth
The milk teeth begin to drop out at the age of
six years and are gradually replaced by the second set of teeth called the
permanent teeth. In man the milk teeth do not fall off simultaneously, they
fall off one by one and similarly permanent grow one by one as well. Healthy
teeth are strong and give a beautiful and lustrous look. You must brush your
teeth at least twice a day.
Structure of a Tooth
A tooth has two permanent parts, the Crown and
the Root. The crown is that part of tooth which projects out of the gum and
jaws. The root the the tooth is embedded into the gums and is therefore,
hidden.
Enamel
This is the outer most part of tooth which is
very hard and lustrous. It is deposited on the outside of the crown of the
tooth by cells in the gum. The enamel is a non-living substance. It is made up of
calcium salts. It imparts beauty to the tooth and protects the tooth. If the
enamel gets removed then the teeth start decaying.
Dentine
It is the part of teeth present under the enamel
which is hard. But it wears off if the enamel gets removed. Running through the
dentine are strands of cytoplasm arising from the cells in the pulp. These
cells keep on adding more dentine to the inside of the tooth.
Pulp
The innermost part of the tooth is hollow and is
made up of soft connective tissue which is called the pulp. The strands of
cytoplasm in the dentine derive their food and oxygen from the pulp which
enables the tooth to live and grow. The pulp contains sensory nerves and blood
capillaries. These nerve endings are sensitive to heat and cold and can produce
the sense of pain e.g. toothache.
Cement
Cement is a thin layer of very hard material
which covers the dentine at the root of the tooth. the fibers holding the tooth
in the jaw are embedded in the cement at one end and in the jaw at the other.
In this way teeth remain firmly embedded in the jaws.
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Protection and Cleanliness of Teeth
Teeth are a gift of nature. For a good health,
presence of clean, good healthy teeth is necessary if we wish our teeth to
remain healthy; we should wash and clean them after every meal. Our tongue
helps in cleansing the upper portion of teeth to some extent. If food particles
are firmly trapped up between the teeth, or between gums and teeth, then it
becomes difficult to remove them with the tongue. The main cause of tooth decay
is a sugar coating left by sugary food on the teeth, which is converted into
acid by bacteria. The acid damages the enamel and allows the bacteria to infect
the soft dentine and reach the pulp cavity. The dentine begins to decay and
causes toothache. Sugary foods such as sweets, toffees and chocolates, the
bacteria which cause decay, form a thin layer of scum over the surface of the
teeth. This layer becomes very hard with the passage of time and becomes
difficult to remove. This scum is called plaque.
The teeth should be cleansed properly and
regularly with a miswaak or a tooth brush. So that there is no formation of
plaque. We should eat less sugar or sweet and sticky foods and also cleanse the
teeth afterwards. Balanced diet should be taken, especially by young people who
have growing teeth.
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Health Problems Related to Nutrition
Friendsmania.net
Under Nutrition
During under nutrition a person's diet is
deficient in the required calories. children are mostly affected due to
availability of less than normally required diet and they suffer from a disease
called marasmus. In this disease, children are reduced to a skeleton as the
body becomes completely depleted. Some of the countries like Ethiopia are
famine stricken. Although international community does try its best to rescue
the famine inflicted areas yet it is not possible for them to meet their
complete nutritional requirements on such a large scale. The world population
is continuously and rapidly increasing each year. It has been estimated that by
2025, the world population will rise to ten billion, whereas water and soil
resources are being continuously depleted by increasing use by the continuously
growing population. The experts therefore envisage that increasing human
population if not checked will soon eat up all the food resources of the world
which may lead to destruction of human race.
Malnutrition
If malnutrition (a diet missing in one or more
essential nutrients) continues for a prolonged period, particularly under
special circumstances, such as during pregnancy or immediately after
childbirth, it is found to be very harmful.
If malnutrition occurs during lactation period,
it causes irrepairable damage to the infant. During the last quarter of
pregnancy when foetus is rapidly developing its cerebral tissues, the protein
deficient diet of the mother results in mental retardness and nervous
abnormalities in foetus, which may prove fatal or lead to permanent disorders.
These abnormalities may also occur in infants if the lactating mother is taking
a protein deficient diet during the first year of breast-feeding.
If a human diet lacks essential elements or
nutrients, the body will fail to prepare vital compounds, and thus the person
will suffer from various diseases. Deficiency of a few amino acids, vitamins,
fatty acids (about thirty compounds) and 21 mineral elements, called as
essential nutrients in diet are responsible for various diseases.
In the poor countries like ours packaged or junk
food(sugar coated cumin seeds, betal nuts, chewing gums and drinks) are not
prepared under proper care. The food colours scents and flavours are added to
make them commercially attractive. But these are substandard and harmful for
human health. The use of food additives may be the cause of dangerous diseases
like cancer and ulcer etc. These items should, therefore, be avoided.
Over Nutrition
It is the problem of the developed countries
where people eat too much. Obesity is the most common disorder due to over
nutrition. Obesity is the cause of a large number of diseases too.
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Methods
of Food Preservation
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Pasteurization
This method was discovered by famous biologist,
Louis Pasteur. By this method milk is prevented from turning sour. In this
process, milk is heated to 71 C for a few seconds and then cooled rapidly. This
kills most of the bacteria. The bacteria which survive this treatment may
become retarded in growth. In this way, the milk is preserved for a few days.
Refrigeration
In this methods, food is kept at very low
temperature usually below freezing point. It retards the action of enzymes and
the growth of bacteria. In deep freezers food can be preserved for many years.
Quick freezing helps to maintain the taste and texture of meat, fruit and
vegetables.
Dehydration
In this method food is dried. Such food can be
kept safe for a long period at normal temperature. Bacteria do not grow without
water, therefore when water content is removed from meat and vegetables, they
can be preserved for long durations. Pickling of food is another common
indigenous technology in which taste and texture of pickled food is maintained
for long.
Canning
In this method the food is first heated at a
high temperature. This kills bacteria and destroys enzymes. Then, the food is
sealed in a metallic container. In this way; food becomes safe from
contamination. Metallic cans are usually lacquered to prevent food from
chemically reacting with metals and producing toxic substances.
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Nutrition
and Food Technology
Friendsmania.net
For thousands of years, man has been making
efforts to grow more food for storage so that it can be used when needed.
Modern man knows how to preserve food for use subsequently when needed. Man has
adopted modern techniques of food preservation in which its nutritional value
and taste are preserved. Foods are damaged by bacteria; fungi and other
micro-organisms, which occur everywhere. These organisms make food unsafe for
use and storage, so it is necessary to kill bacteria or other organisms as soon
as they enter food.
Early methods of preservation affected the taste
of the preserved food, but modern scientific techniques prevent contamination
of food, keep the taste and make it consumable even after a long period of
storage. To achieve this, temperature plays an important role.
Food that we take is usually made up of dead
tissue and it can be spoiled for two reasons, either the food is contaminated
and destroyed by bacteria or fungi or the enzymes still active in tissue start
breaking down the cells, thus making food poisonous and tasteless to eat.
All bacteria, fungi and micro-organisms must be
killed or their growth must be retarded in order to protect the food from
spoilage. Heat is the best source, as extreme increase in temperature retards
bacterial growth and enzymes can also be denatured. Thus temperature extreme
can be useful in the preservation of food.
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Dietary
Fiber (Roughage)
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These are foods which provide fibers to our
body.
Sources of Dietary Fibers
All fruit and vegetables provide fibers to the
body for example, citrus fruits, cereals, spinach, cabbage and salads. The cell
wall in plant cells are largely made of cellulose which cannot be digested by
man. Bacteria living in the gut of ruminants digest the cellulose and convert
it into fatty acids, which renders it absorbable.
Importance of Dietary Fibers
1. Roughage adds bulk to the food enabling the
muscles of the alimentary canal to grip it and keeps the food moving by
peristalsis.
2. Absence of roughage in our diet may lead to
constipation and related disorders.
3. Fibers keep the intestines in a healthy
condition, thus our daily diet must contain a lot of fruit and vegetables.
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Role
of Water
Friendsmania.net Water
Water makes approximately 70% of the body
tissues. It is an essential component of the protoplasm. One can live without
food for more than a week but a person can die within two to three days due to
lack of water.
Importance of Water
1. It plays an important role in digestion.
2. It helps in transport of digested food and
other materials in dissolved form.
3. All the chemical reactions inside the cell
take place in the presence of water.
4. It helps in excretion of urine, removal of
faeces.
5. Enzymes become more active in solution form.
6. It keeps the blood thin and so that it can be
easily circulated.
7. Water regulates the body temperature.
8. Its deficiency in tbe body causes
dehydration, which can prove fatal.
9. Plants cannot photosynthesize without water.
10. The people living in hot and dry places need
more water. By breathing, sweating and urination about 2-3 liters of water is
lost per day.
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Mineral Salts
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Mineral salts are inorganic compounds. They do
not provide energy to the body. However, they are required for the normal
chemical activities of the body. Man can obtain them from animals or plants
which absorb them from the soil. Some minerals are needed by man and mammals in
relatively large quantities, other are required in very small quantities.
Trace Elements
The mineral required by organisms in minute
quantity are called Trace Elements.
Few Important Minerals
Calcium, Sodium, Potassium, Magnesium, Chlorine,
Iron, Phosphorous and iodine etc.
Role of Minerals
Sodium Chloride
It helps to make hydrochloric acid in the
stomach which is very important for the digestion of food. Along with potassium
it helps to conduct messages through nerves.
Potassium
It is found in the living cells especially in
the red blood cells and muscles and it helps in the growth of the organism. The
body acquires it through cereals.
Magnesium
It is an important component of the bones. It is
obtained by eating different vegetables. It helps the enzymes which control
different metabolic reaction.
Calcium
It plays an important role in strengthening the
bones and teeth. It helps in blood clotting, muscular contraction and in the
conduction of nerve impulse. It is found in milk, eggs, fruit, cereals and
green leafy vegetables.
Iron
It is very important mineral. It helps in making
hemoglobin in the red blood cells. It occurs in meat, liver, eggs, peanuts, spinach
and other vegetables.
Flourine
It helps in the growth and development of the
bones and teeth. If it is mixed in drinking water in suitable amounts, dental
decay (caries) can be reduced in children. The body can obtain this mineral
from vegetables and fish.
Note: In addition to these mineral trace
elements like cobalt, manganese, zinc and copper are also necessary for the
better health of the human body.
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Vitamins
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Vitamins are very complicated compounds. When
vitamins were discovered, their chemical nature was not well known. Therefore,
they were denoted with English letters as A, B, C, D, E and K. Now it is known
that vitamin B is not a single vitamin but a group of vitamins call ed as
vitamin B complex. It has eight different compounds as B1, B2 etc although they
have no energy value but they are essential in small quantities for the normal
activities of life. It has been observed that when animals were given a diet
rich in carbohydrates, fats and proteins but lacking vitamins, the growth and
development of the organisms were affected and the animal suffered from various
diseases. Vitamins are needed for healthy growth and development of the body.
They also serve as enzyme.
Plants can prepare their vitamins from simple
substances but animals obtain it directly or indirectly from plants. Fifteen or
more vitamins have been isolated and most of them seem to act as essential part
of coenzyme involved in chemical changes taking place in the body.
If our diet has variety and consists of fresh
fruit and vegetables, our body will receive all those vitamins which are
necessary for us.
Fat Soluble Vitamins
Some vitamins are fat-soluble and can be stored
along with fat.
Water Soluble Vitamins
Some vitamins are water soluble and hence cannot
be stored in the body, thus their in take is required continuously.
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Lipids
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Lipids are obtained from two sources:
Animal Sources
Ghee, butter, cream, animal fat and fish oil.
Plant Sources
Oils from mustard, olives, coconut, maize, soya
beans, sunflower and peanuts.
Importance of Lipids
1. The use of fat rich products increase in
winters because they provide double the amount of energy as compared to
carbohydrates.
2. They provide 9000 cal/gm energy to the body.
3. In plants fats are stored in seeds, and in
animals, they are found beneath the skin and around the kidneys where they are
not only stored but also protect these parts.
4. They provide materials for building new
protoplasm and cell membrane.
5. Some fatty acids are essential for man.
6. Saturated fats (animal fats) should be used
with, great care in our diet as they lead to rise in the cholesterol level,
which accumulates in the blood vessels, and thus affects the flow of blood in
the arteries This can result in heart attack.
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Nutrition
in Man
Like all other animals human beings need food
for following activities:
1. To get energy this may be used to carry out
different activities in the body.
2. To build new protoplasm in the cells, renew
and replaced damaged cells and tissues for grwoth and reproduction.
3. To maintain health and build resistance
against various diseases.
Man's diet consists of following components:
1. Carbohydrates
2. Proteins
3. Lipids
4. Vitamins
5. Mineral Salts
6. Water
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Photosynthesis
Friendsmania.net
Photosynthesis is a Latin word derived from two
words photo (light) synthesis (building up). In this process, green plants
manufacture carbohydrates from carbon dioxide and water. The energy needed for
this process is obtained from sunlight, which is absorbed by chlorophyll and
oxygen is produced as by-product. Leaves are the major sites of photosynthesis
in most plants but all green parts of a plant including green stems; un-ripened
fruit can carry out photosynthesis. Temperature also plays a very important
role in photosynthesis. Temperature affects the rate of photosynthesis. This
process occurs during day time only.
Conditions and Factors Necessary for
Photosynthesis
Water
Plants need water for many functions of life.
Water enters the root hair from the soil. It passes through various cells and
reaches the xylem of the root. From here it moves to the stem and then the
veins of the leaves. Finally, it reaches the mesophyll cells in the leaves. It
provides hydrogen for the synthesis of glucose and helps in opening and closing
of stomata. If leaves get less water, less stomata open, this reduces the rate
of photosynthesis. Opening of more stomata provide more carbon dioxide for
photosynthesis.
Carbon Dioxide
This is an important factor which affects
photosynthesis. The amount of carbon dioxide in the atmosphere is about 0.03%
and does not vary much. Its amount differs from place to place which may affect
the rate of photosynthesis. e.g. the concentration of carbon dioxide close to
the ground in a dense forest is higher than in an open field. Although carbon
dioxide is needed in very little amount by the plants, yet photosynthesis
cannot take place without it. It diffuses from the air into the intercellular
spaces through stomata and enters the chloroplasts in the mesophyll cells.
Carbon dioxide provides carbon to build up glucose molecule. If the amount of
carbon dioxide in the atmosphere increases to 1% rate of photosynthesis also
increases, and it starts decreasing if concentration of carbon dioxide is
decreased. If the concentration of carbon dioxide decreases below 0.03% the
rate of photosynthesis also declines.
Chlorophyll
It is the green substance. It is found in
special organelles called chloroplasts, which are found in the green leaves and
herbaceous stems. In leaves, it is present in the mesophyll cells. Chlorophyll
changes light energy into chemical energy and makes food in plants. Plants
lacking chlorophyll cannot carry out photosynthesis occurs only in those parts
where chlorophyll is present.
Sunlight
Light is very important for the process of
photosynthesis. Without light the photosynthesis cannot take place. It provides
energy needed for the synthesis of glucose molecule. Light intensity varies
from day to day and from place to place. Plants photosynthesize faster on a
bright sunny day than on a cloudy day. While light consists of seven colours.
The blue and red are best for photosynthesis.
Is Chlorophyll Necessary for Photosynthesis?
Experiment
Since it is not possible to remove chlorophyll
from a leaf without killing it, so it becomes necessary to use a leaf where
chlorophyll is present only in patches. Such a leaf is known as variegated leaf
and a plant with such leaves is used in this experiment.
For destarching the leaves, the pot is kept in a
dark place for a couple of days and then exposed to day light for a few hours.
The leaf is then removed from plant. Its outline is carefully drawn to note the
position of presence or absence of chlorophyll on it.
Now iodine is applied to the leaf to test for
the presence of starch (starch when ever comes in contact with iodine turns
blue).
This test shows that only those parts which were
prevously green turned blue with iodine while the white parts turned brown.
This result indicates that starch is formed only in those parts of the leaf
where chlorophyll exists (i.e. green parts). In other words photosynthesis is
not possible without chlorophyll. If this were possible the white parts of the
laf should have also given a blue colour with iodine.
(Diagram)
Is Light Necessary for Photosynthesis
Experiment
A potted plant is destarched by keeping it in
the dark room for two days. It is then transferred to light. Two of its leaves
are selected for the examination. One leaf is wrapped completely in black
paper. The other leaf is also wrapped in black paper but an L-shaped part of
the paper is cut out so that light can reach this part of the leaf through it.
The plant is placed in the sunlight for 4 to 6 hours. The two leaves are now
detached from the plant and tested for presence of starch. It would be observed
that the leaf which does not receive any light is free of starch (remains brown
with iodine). However, in the second leaf, light could pass through the
L-shaped opening in the black paper. Only this L-shaped area turns dark blue
while the other parts of the leaf remain brown. This shows that light plays a
vital role in the manufacture of starch since starch is manufactured due to
photosynthesis, light is essential for this process.
(Diagram)
Is Carbon Dioxide Necessary for Photosynthesis
Experiment
Two potted plants are destarched by keeping them
in a dark room they are watered properly during this period. Each pot is
enclosed in a transparent polythene bag as show in figure. A petri dish
containing soda lime (potassium hydroxide) is placed on one of the pots to
absorb any carbon dioxide present in the polythene bag. In the other pot a
petri dish is placed containing sodium bi-carbonate solution which would
produce carbon dioxide. The plants are then left in light for several hours. A
leaf from each pot is detached and tested for starch. The leaf from the pot
containing soda lime does not turn blue. soda lime had absorbed any carbon
dioxide present in the bag. The leaf from the other pot where carbon dioxide
was being released by the sodium bicarbonates solution turns blue indicating
the presence of starch. These results show that carbon dioxide is essential for
photosynthesis.
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Fats and Oils
They are also organic compounds found in plants,
animals and humans. They are very important compounds made up of carbon,
hydrogen and oxygen. Fats contain more carbon and hydrogen as compared to
oxygen. A fat molecule has two parts, glycerol and fatty acids.
Fatty Acids
Different kinds of fats contain different fatty
acids. Fatty acids are basically of followin two types:
1. Unsaturated Fatty Acids
2. Saturated Fatty Acids
Unsaturated fatty acids (molecules with one or
more than one double bonds) are liquids at room temperature and are called
oils. These are good for human health. Saturated fatty acids (molecules without
double bond) are solid at room temperature and are called fat. They are not
good for human health because they increase cholesterol level in the body. They
cause narrowing of blood vessels which may result in heart attack.
Vegetable Sources
Vegetable fats are liquid and are called oils
e.g. mustard oil, olive oil, coconut oil, corn oil. etc.
Animal Sources
Animal fats are solids e.g. butter, ghee and
fatty meat.
Source of Energy
Fats and oils are rich source of energy they
provide double energy as compared to carbohydrates and proteins. One gram of
fat on oxidation releases 9.1 kilo cal of energy to make ATP.
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Proteins
- Food and Nutrition -
Friendsmania.net
Proteins
Proteins are very important organic compounds
found in all organisms. Proteins contain carbon, hydrogen, oxygen and nitrogen
and sometimes some amount of sulphur. There is no 2:1 ratio between hydrogen
and oxygen. A protein molecule is composed of many building units linked
together to form a chain. A chain of amino acids is called polypeptide. Amino
acids are building units of a protein molecule. About twenty different amino
acids occur in nature that combines in different manners to make different type
of proteins. Proteins are structural part of the cell membrane. Some proteins
are fibrous. They form different structures in the body like muscles, bones and
skin. They also occur in our blood and cells. The enzymes which control
different chemical reactions in the body are also proteins in nature. As a
result of protein catabolism, energy is released. One gram of protein produces
4.3 kilo cal of energy which is used to synthesize ATP.
Amino Acids
Plants can synthesize all the amino acids they
need from carbohydrates, nitrates and sulphates but animals can not synthesize
all amino acids. Amino acids are the building units of proteins.
There are about twenty different types of amino
acids which are used in the synthesis of protein found in the human body.
Non-Essential Amino Acids
There are many amino acids which a human body
can synthesize within the body. These are called non-essential amino acids.
Essential Amino Acids
There are approximately ten amino acids, which
human beings cannot make. These are called essential amino acids and can be
obtained directly from proteins in the diet.
Sources of Proteins
Following are the sources of proteins:
Animal Sources e.g. meat, fish, chicken, milk
and cheese.
Plant Sources e.g. legumes, pulses, dry fruit
and cereals.
Importance of Proteins in Human Body
1. Proteins are essentially required for growth
and development.
2. Growing children ,pregnant women and
lactating mothers need a lot of proteins.
3. An adult requires 50-100 gms of proteins
daily.
4. Protein deficiency in children and cause a
disease called Kwashiorkor.
5. Proteins play an important role in the
building of cellular protoplasm.
6. They also play an important role in the
building of muscles and connective tissues.
7. Many proteins are required for making
enzymes, hormones and antibodies.
8. If proteins are eaten in excess than needed
by body, the excessive amino acids are converted into carbohydrates by the liver,
which are either oxidized to release energy and converted into glycogen and fat
and stored.
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Need for Food
* Nutrients of Food and Their Importance
* Carbohydrates
* Proteins
* Fats and Oils
* Photosynthesis
* Nutrition in Man
* Lipids
* Vitamin
* Minerals
* Role of Water
* Dietary Fibers
* Nutrition and Food Technology
* Methods of Food Preservation
* Health Problems Related to Nutrition
* Balanced Diet
* Teeth
* Digestion of Food
* Enzymes
* Light and Dark Reactions
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Food
and Nutrition
Friendsmania.net
* Need for Food
* Nutrients of Food and Their Importance
* Carbohydrates
* Proteins
* Fats and Oils
* Photosynthesis
* Nutrition in Man
* Lipids
* Vitamin
* Minerals
* Role of Water
* Dietary Fibers
* Nutrition and Food Technology
* Methods of Food Preservation
* Health Problems Related to Nutrition
* Balanced Diet
* Teeth
* Digestion of Food
* Enzymes
* Light and Dark Reactions
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Nutrients
of Food and Their Importance
The food of organisms and the organic compounds,
building their bodies are almost same. Their bodies are composed of
carbohydrates, proteins and fats etc. These substances are used by organisms as
their food. They get energy from these substances. They use the components of
food in growth and repairing of damaged tissues. Thus substances acquired by
organisms to obtain energy are called nutrients and the process by which they
are obtained is called nutrition. The food of all organisms which depends upon
already prepared food has been found to consist of six basic components. These
are as follows:
1. Carbohydrates
2. Proteins
3. Fats, Oils
4. Vitamins
5. Minerals
6. Water
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Respiration Chapter 10 - Biology
Friendsmania.net
Respiration
The oxidation of the absorbed food material in
order to obtain energy is called respiration.
There are two types of Respiration in the
organisms:
1. Anaerobic Respiration
2. Aerobic Respiration
Aerobic Respiration
In most of the higher and larger organism, the
glucose etc is oxidized by using molecular oxygen. This type of respiration is
known as Aerobic Respiration. In aerobic respiration a mole of glucose is
oxidized completely into carbon dioxide and water releasing enormous amount of
energy. One glucose molecule in this respiration produces 686,000 calories of
energy. Aerobic respiration thus produces 20 times more energy than the
anaerobic respiration.
In aerobic respiration food is oxidized in
presence of molecular oxygen.
Stages of Aerobic Respiration
There are two stages of Aerobic Respiration:
(a) External Respiration
In this stage, the organisms take the air
(containing oxygen) into their bodies. This is called external respiration.
this stage includes the transport of oxygen obtained from the inhaled oxygen to
each cell of the body.
(b) Internal Respiration
The second stage is called internal respiration.
It consists of the oxidation of glucose, amino acid and fatty acids etc, with
molecular oxygen. In this stage all these reactions are included which extract
the chemical energy of glucose and other compounds and store it in the form of
ATP molecule, this respiration is also called cellular respiration as it occurs
within cells.
In the internal or cellular respiration glucose
and other compounds are passed through such enzymatic reactions which release
the chemical energy gradually in small amounts with the help of which ATP
molecules are synthesized.
Anaerobic Respiration
Some organisms oxidize their food without using
any molecular oxygen. This is known as Anaerobic Respiration. In this type of
respiration considerably less amount of energy is released as compared with the
other type of respiration.
In anaerobic respiration a glucose molecule is
broken down into two molecules of lactic acid with a release of only 47,000
calories of energy.
Glucose --------> 2 Lactic Acid + Energy (47,000 calories)
Importance of Anaerobic Respiration
1. When earth came into being its environment
was totally devoid of oxygen. The aerobic organisms cannot lie in anaerobic
environment. The early organisms started respiration in the absence of oxygen
to produce energy for survival of organisms.
2. Some existing organisms like bacteria and
parasites which live in oxygen environment have anaerobic respiration.
3. Many useful bacteria and yeasts are
anaerobic.
4. Even in the aerobic respiration of the first
phase is anaerobic. The glycolysis which is the first phase of carbohydrate
metabolism involves reaction which does not require the expenditure of
molecular oxygen. This proves the idea that aerobic organisms have evolved from
anaerobic organisms.
5. In our skeletal muscles, although aerobic
metabolism takes place but in sustained activity when the oxygen supply cannot
keep pace with energy demand, anaerobic respiration supplies the energy
continuously by the breakdown of glucose to lactic acid.
ATP (Adenosine Triphosphate)
It is a chemical compound. ATP is an
abbreviation of adenosine triphosphate. Its name indicates that it contains
adenosine and three phosphate groups. Adenosine is formed of a nitrogenous base
called adenine and a sugar called ribose. In ATP three phosphate groups are
attached to the adenosine in a series one after the other.
Significance of ATP
ATP is a big source of energy. The two terminal
bonds between the phosphate groups contain large amount of the chemical energy.
When these bonds are broken in enzymatic reaction, large amount of energy is
released by which energy requiring activities are accomplished, like synthesis of
various compounds of carbohydrates, fats, proteins and hormones etc or for
carrying out any physical work like muscle contraction, heat production or
transport of substances etc.
When the terminal bond is broken the ATP is
changed into ADP and phosphate 7300 calories of energy are released.
Gaseous Exchange in Plants
Plants get their energy from respiration. Plants
have no special organ or system fro exchange of gases. The gaseous exchange in
plants occurs in cells, of every part of the plant i.e. roots, stems and leaves
etc according to their energy demand. The conducting system (xylem and phloem)
of plants transports water and nutrients but plays no role in the transport of
gases. The air spaces present between the cells of parenchyma of leaves, stem
and roots are involved in the gaseous exchange.
Gaseous Exchange in Leaves and Young Stems
In the leaves and young stems, gaseous exchange
occurs through stomata. Some gaseous exchange also occurs through cuticle.
Gaseous Exchange in Woody Stems and Roots
In woody stem and roots, there are present dead
cells beneath the epidermis which form cork tissue. Later on, this tissue
becomes porous. The pores are called lenticels. These are involved in gaseous
exchange.
Gaseous Exchange in Leaves
The aquatic parts obtain oxygen for their
respiration by diffusion from the dissolved oxygen in water. Whereas the land
plants get their oxygen from air directly through their stomata which are more
abundant on the lower surface than the upper surface of leaves.
Gaseous Exchange in Roots
The roots get their oxygen for gaseous exchange
through diffusion from the air existing in the space between soil particles.
Process of Respiration in Plants
The respiration in plants continues day and
night. In this process, the oxygen from the airspaces in the leaves and stems
is diffused into tissues and cells after getting dissolved in the film of water
which is present over the cells. In the cells this oxygen oxidizes the
carbohydrates and other organic compounds into carbon dioxide and water to
produce energy. Some of the water (vapours) comes in the airspaces from where
they diffuse out to the atmosphere through lenticels and stomata. The
elimination of carbon dioxide is more evident from the parts without
chlorophyll like growing seeds and buds. The water produced in this process
becomes a part of the already present water in the body of plants. The various
chemical reactions of respiration are controlled by the specific enzymes. This
process occurs at a faster rate in the parts of the plant having rapid growth
like growing seeds, buds, apical meristem of roots and shoots, because these
parts require more energy to accomplish the growth process.
Relationship between Respiration and Photosynthesis
The gaseous exchange in plant is not very
evident during the day time as the products of respiration i.e. carbon dioxide
and water are used in the process of photosynthesis. In the bright sunshine,
because of high rate of photosynthesis the carbon dioxide produced in respiration
falls short and therefore, some carbon dioxide has to be taken into the plant
from outside for photosynthesis.
In the day time the plants therefore, take in
carbon dioxide and expel out oxygen. The process of photosynthesis occurs in
chloroplasts whereas the process of respiration takes place in cytoplasm and
mitochondria.
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Gaseous Exchange in Animals
The gaseous exchange in different animals takes
place by different methods and organs. In unicellular aquatic animals like
amoeba, the dissolved oxygen in water diffuses directly through their cell
surface into the interior of the animal and the carbon dioxide similarly
diffuses out from their bodies into the external water. This is the simplest
way of gaseous exchange and it can occur only in small animals with a diameter
of less than one millimeter. These animals have greater surface area of volume
ratio and have low rate of metabolism.
During evolution, as the animals became complex
and complex and grew in their size, their skin or external body surface become
impervious to water. Thus the gaseous exchange became impossible through
diffusion. In large animals certain organs were developed for exchange of gases
w.g. the moist vascular skin, gills, lungs and tracheoles. These large animals
have developed blood vascular system which transports oxygen from the
respiratory surface to the deep cells and tissues in all parts of the body. The
blood in all animals has some respiratory pigments like haemoglobin which carry
large amount of oxygen efficiently from respiratory surface to the interior
cells.
Properties of a Respiratory Surface
1. Respiratory surface should have large surface
area.
2. Respiratory surface should be moist.
3. Respiratory surface should be thin walled.
4. Respiratory surface should have blood supply.
Gaseous Exchange Through Skin
For the exchange of gases through the skin the
skin must be moist and richly supplied with blood. The oxygen is diffused from
the external water to the blood and the carbon dioxide is diffused from the
blood to exterior water. In amphibia and fishes the gaseous exchange occurs
through the skin besides through the gills or lungs. The frogs and tortoises
breath through the skin during their hibernation period.
Gaseous Exchange by Gills
The gills are very effective for gaseous
exchange in aquatic animals. Gills are of two types:
(a) External Gills
(b) Internal Gills
(a) External Gills
Some animals have external gills which project
out of body of animals. These gills have very thin and highly vascularized
surfaces e.g. the dermal papillae of star fish and arthropods.
(b) Internal Gills
These are present inside the body inner to skin
e.g. in fishes and arthropods. Have you ever examined a fish closely? How ill
you know that the fish is fresh or not? If the colour of gills is red then it
is fresh but if the colour of gills is changed, it is definitely not fresh. The
red colour of the fish gills shows the presence of oxygenated blood.
Gills of Fish
In fishes the gills are present in the branchial
cavity present on lateral sides of the body behind the head. This branchial
cavity is covered over by an operculum. There is a counter current flow of
water and blood in gills which ensures maximum exchange of oxygen and carbon
dioxide between the blood and the bathing water. Water enters through the
mouth, flows over the gills and goes out of the body from the opercular
aperture.
Human Respiratory System
In humans, there is very efficient respiratory
system. It consists of certain organs which are called respiratory organs these
include nose, pharynx, larynx, trachea, bronchi and bronchioles.
Nose
The air enters through the external nostrils
into the nasal cavity. This is lined with mucous secreting epithelium and
ciliated epithelium. The nostrils are lined with hairs. The nasal cavities,
located above the oral cavity and behind the nose are covered with epithelial
tissue.
The beating of cilia creates a current in the
mucus that carries the trapped particles towards the back of the nasal cavity.
From here the mucus drips into the throat and is swallowed. Mucus keeps the
nasal cavities moist. Bones of the nose warm up the air. Mucus moistens the
air. Hair filter the air and stop the dust particles bacteria and any other
foreign substance from going to next part of respiratory system. In this way
air is purified and is then pushed into the pharynx.
A number of cavities called sinuses open into
the nasal cavity. The sinuses are lined with mucus secreting epithelium. The
opening of sinuses into the nasal cavity is very narrow. If these openings are
closed due to cold or inflammation, the sinuses get filled up with mucus this
results in headache and changed voice.
Pharynx
The nasal cavity opens into the pharynx (throat)
through two small apertures which are called internal nares or internal
nostrils. The pharynx is muscular passage which extend from behind the nasal
cavities to the opening of oesophagus and larynx. The air goes from the pharynx
into the larynx.
Larynx
The upper most part of the wind pipe (trachea)
is called the larynx. The larynx is a cartilaginous box. Two fibrous bands
called vocal cords are located in this box. These vibrate to produce sound.
Larynx is, also called sound box or voice box. The air enters the larynx
through a small aperture called glottis which is guarded by a muscular flap
called epiglotis which fits into this opening while the food is being swallowed
into the oesophagus. It prevents the food from entering into the trachea and
choking it. During breathing epiglottis keeps the glottis open so that air goes
to trachea.
Trachea
The air tube (wind pipe) is known as trachea. It
is about 12 cm long and lies in front of the oesophagus. It has incomplete C
shaped cartilagenous rings which are regularly placed in its wall and all along
its length. These rings prevent the collapsing of the tube nd thus keep the air
passage wide open all the time. Trachea is also lined with ciliated mucous
epithelium. Any foreign particles present in the inhaling air get trapped in
the mucous that is moved out of the trachea by breathing of the cilia in the
upward direction. In trachea air is further cleansed and filtered and then
moved towards the lungs.
Bronchi
The trachea while passing the chest cavity
divides into two smaller tubes which are called bronchi (single bronchus).
Bronchi are similar in structure to the trachea but are smaller in diameter and
they have in their walls small irregular catilageuous plates. Each bronchus
enters into the lungs of its own side. The right bronchus divides into three
secondary bronchi and the left bronchus divides into two secondary bronchi
which serve the 3 right and 2 left lobes of the lungs respectively.
Bronchioles
the secondary bronchi further divide into very
fine branches until they end in thousands of passage ways called respiratory
bronchioles. The bronchioles have not cartilaginous plates in their walls. They
have smooth muscle and elastic fibers.
Alveoli
The walls of the respiratory bronchioles have
clusters of tiny branches(like bunches of grapes) that along with the
respiratory bronchioles re the sites of gaseous exchange, these pouches or air
sacs are called alveoli (singular: alveolus). The alveoli are enormous in
number. Each lung has about three hundred million alveoli.
Pulmonary artery brings deoxygenated blood from
the heart into the lung. Here, it divides and re-divides until it forms a
network of fine capillaries over the wall of each alveolus. The walls of
alveoli are very thin (1/1000 mm thick) and moist. Thus, alveoli are efficient
site for gaseous exchange.
The Lungs
There is a pair of lungs present in the chest in
man. Actually, the masses of alveoli constitute lungs and their lobes. The
lungs re protected by the chest box from sides and by a doem shaped muscular
diaphragm from below. Chest box or ribcage is made up of ribs. Between the
ribs, there are present inter-costal muscles. The diaphragm is a muscular sheet
which partitions the chest and abdomen.
The two lungs re covered by a double layered
membrane called pleural membrane. There is a thin film of fluid in between the
two layers. This watery fluid makes the movements of the lungs (expansion and
contraction) easy. It also protects the lungs from external injuries.
(Diagram)
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Mechanism of Breathing
Breathing occurs in two phases:
1. Inspiration
2. Expiration
Inspiration
1. During inspiration, the dome-shaped diaphragm
contracts and becomes flat some what and thereby lowering the floor of the
thoracic cavity.
2. The external inter-costal muscles contract
raising the ribcage. A combined action of these two events expands the thoracic
cavity, which in turn expands the lungs.
3. The air pressure within the lungs decreases.
4. Thus air from the environment outside the
body is pulled into the lungs to equalize the pressure of both sides.
Expiration
1. The diaphragm relaxes and assumes dome like
shape. During expiration, the external inter-costal muscles relax and the
internal inter-costal muscles contract as a result of which ribcage drops.
2. The combined action of these two event
decreases the volume of the thoracic cavity which in turn decreases volume of
lungs.
3. The air pressure with in the lungs increases.
4. The air is thus forced out of the lungs.
Bad Effects of Smoking on Heath
Smoking is injurious to human health. The smoke
contains many chemical and gases. Dried tobacco leaves are used in cigarettes.
The tobacco on burning produces a number of dangerous and toxic compounds.
Chemicals Present in Cigarette Smoke and Their Harmful Effects
(a) Nicotine
1. Man is addicted to cigarette damages brain
tissues.
2. Causes blood to clot more easily.
3. Harden walls of arteries.
(b) Tar
1. Kills cells in air passages and in lungs.
2. Increases production of mucous and phlegm in
lungs.
3. Causes lung cancer.
(c) Carbon Monoxide
Prevents red blood cells from combining with and
transporting oxygen around the body.
(d) Carcinogens
promote the growth of cancerous cells in the
body.
(e) Irritants
1. Irritate air passages and air sacs in the
lungs.
2. Kill cells at the surface of air passages.
3. Causes smoker's cough and lung cancer.
Combustion
A chemical reaction in which a substance combines
with oxygen and produce heat, light and flame is called Combustion.
Respiration
A process that liberates chemical energy from
organic molecules when oxidized is called Respiration. It occurs in all living
cells. In fact respiration is a series of complex oxidation and reduction
reactions in which energy is released bit by bit.
Photosynthesis
The process in green plants by which green
plants manufacture their own food by using carbon dioxide and water with the
help of energy absorbed by chlorophyll from sunlight is called photosynthesis.
Relation of Combustion, Respiration and Photosynthesis
Combustion is the process of burning in which
wood, coal, methane, gas etc are burnt in the presence of oxygen, producing
carbon dioxide and water accompanied with the release of energy. It is an
exothermic chemical reaction.
Cellular respiration can be compared to burning
of fuel in which organic food (carbohydrates, fats and proteins) rich in carbon
burn in the presence of oxygen producing carbon dioxide, water and energy.
Respiration like combustion is a catabolic
exothermic chemical process. However, the difference between the combustion and
respiration is that the combustion takes place in one go, releasing the entire
energy as the heat, which may be utilized or is lost into the environment. the
respiration completes in several small steps. Each step is under the control of
a specific enzyme, releasing energy in small amounts which can be stored in the
form of ATPs. Photosynthesis, another metabolic process, is just opposite to
combustion. Combustion is a catabolic process; the photosynthesis is an
anabolic process. In photosynthesis organic substance is synthesized from
carbon dioxide and water in the presence of sunlight energy and chlorophyll.
The molecular oxygen is evolved as the by-product combustion is exothermic and
releases energy, photosynthesis is endothermic and absorbed energy.
Photosynthesis and respiration are the two
metabolic reactions opposite to each other. Photosynthesis takes place only in
the gree parts of the plant body having chlorophyll, whereas respiration takes
place in all the living cells of plants and animals. Mitochondria are the
cellular organelles where respiration takes place while the organelles for
photosynthesis re chloroplasts. Photosynthesis takes place during the day time
only, whereas respiration takes place day and night. In photosynthesis body
weight is increased but in respiration weight is decreased. Respiration is an
oxidation reaction whereas photosynthesis is a reduction reaction and can be
well understood by comparing their chemical reactions.
(Diagram)
Chemical Equation in Respiration
Glucose + Oxygen -------> Carbon dioxide + Water + Energy (In
presence of mitochondria and enzymes)
Chemical Equation In Photosynthesis
Carbon dioxide + Water --------> Glucose + Oxygen (In
presence of chloroplast and solar energy)
Respiratory Organs of Insects
The respiratory system of insects is called the
Tracheal system. It is a network of interconnecting air filled tubes called
trachea delivering air directly to the body tissue cells. Trachea open outside
through pores called spiracles.
Each trachea has chitinous cuticle lining which
prevents it from collapsing.
A pair of spiracles is usually located on the
sides of each segment of the thorax and abdomen. Spiracles have valves to open
or close them regulated by special muscles. This controls water loss from
internal body tissue.
(Diagram)
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Trachea break up into numerous smaller tubes
called tracheoles which ramify among the body tissues ending blindly.
Tracheoles lack a chitinous lining. At rest the tracheoles are filled with
watery fluid through which gaseous exchange tkes place in dissolved state.
Ventilation is brought about by contraction and
relaxation of abdominal muscles which result in a rhythmic pumping of air into
and out of the trachea.
Gas exchange takes place in tracheoles which are
permeable to gases and are filled with a fluid in contact with the body tissue.
Since oxygen diffuses directly into the tissue cells, blood of insects does not
have hemoglobin so it is white. However, removal of carbon dioxide is dependent
on blood plasma which takes it up for removal via spiracles.
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