Introduction to 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.
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.
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.
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.
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
Virus, Bacteria and Cyano Bacteria
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.
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
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
Invertebrata
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