BLAS notes

Nature of Biology

The word Biology comes from Greek words, Bios = life, logos= study, knowledge or discourse. It is the branch of Natural Science which deals with various aspects of living beings (animals and plants). Biology tries(seeks) to understand how animals and plants perform their life activities , how they interact with each other and with non living things. So, it is most appropriately called as the life science.

Though the definition of Biology is very simple, it is equally complex and extensive as it deals with various aspects of enormous number of living organisms spread in time and space.

This branch of science deals with structural organization of living organisms, functions of their body parts, habitat, relationship and interaction among themselves and surrounding. How they pass their specific characters to the next generation ? How do they evolve from simple or primitive to more advanced forms ?

Biology must have born very early in the remote past out of simple curiosity of man about himself and the living world around him. The study have begun in search of different articles of human use from living world so as to lead comfortable life. The science of living organism is as old as the history of man himself. However the first conceivable evidence of the study of living organisms comes from the work of great Greek philosopher Aristotle ( 384 – 322 BC) . He arranged all living organism in a hierarchy placing the simplest organism at the bottom and man at the top. Due to this creditable work, Aristotle is known as the Father of Biology. He is also known as the Father of Zoology and Founder of Embryology.

The term Biology was first used by French Naturalist Lamarck and Treviranus in 1801.

Scope of Biology

Biology is very much important branch of Natural Science. From the very ancient time, man has been benefited from the various parts of animals and plants found around him. The animals and plants are found to be helping man in various ways in making his life much easier.

Understand human life -- We are curious to know about our own health. Why we eat? How we grow? How we see and hear? What is the importance of balanced diet? The knowledge of Biology can help us to get the right answer of all such questions and others like these.

Understand natural phenomena -- Natural phenomena like flowering of plants, breeding mechanisms and seasons of animals, social behavior of some insects , dispersal mechanism of seed etc can better understood by the study of Biology.



Understand mechanism of

Heredity - the transmission of characters from generations to generations.
Evolution - Development of higher organisms from simple ones
Adaptation – Adjustment of organisms.
Scientific theory- various experiment are carried out on crops, animals like mice, guinea pig and their application on man.

Fulfill the basic need – Skillful biological techniques can be used to fulfill the need of food, shelter, clothes and drugs by improving farming practices.

Control population -- The knowledge of reproductive physiology of man and other harmful animals and plants can be used in controlling their population.

Control epidemics -- The epidemics like Malaria, Encephalitis, Sleeping sickness due to insects as vectors can be controlled by knowledge of feeding mode, life cycle, breeding habit etc.

Conservation of wild life -- if we know the habitat, feeding habit, breeding season etc, we can easily conserve these rare type of wild life.

Careers in Biology
A. Pure Science - Zoology, Botany, Microbiology, Genetics Entomology etc.
B. Medical Science - Homeopathy, Allopathy including Dental, Nutrition. Etc
C. Applied Science – Apiculture, Forestry, Fisheries, Diary technology, sericulture, soil science, Food technology, Animal husbandry etc


Branches of Biology

Biology is vast subject. We can not study Biology as a whole in our life. Our life is very short. To make the study of Biology much easier, it has been divided into various branches or fields or disciplines. We can study the branches of our interests.

The branches of Biology on the basis of the structure and function:

Morphology -- the study of external features of organisms
Anatomy -- the study of internal structure of organisms as seen by naked eye.
Cytology – the study of structure and functions of cell and cell inclusions.
Histology -- the study of structure and functions of cells that make up the internal organs of organisms.
Physiology -- the study of the functioning of organs of organism.



The branches of Biology on the basis of the specific unit or field:

Toxicology – the study of the toxic substances and their effects
Embryology -- the study of the development of organism
Evolution -- the study of origin of life and development into modern plants and animals.
Microbiology -- the study of micro organisms or microbs.
Parasitology – the study of parasites and their effects.
Ecology – the study of relationship between living organism and environment.
Paleontology – the study of animal or plant fossil

The branches of Biology on the basis of the specific group of organisms:

Entomology – the study of insects.
Protozoology -- the study of unicellular organisms
Parazoology – the study of sponges.
Cnidology – the study of Coelenterates like Hydra etc
Bacteriology – the study of Bacteria.
Virology – the study of Virus
Ornithology – the study of Birds

The branches of Biology related to the medical science:

Cardiology – the study of structure and function of heart
Nephrology -- the study of structure and function of kidney
Oesteology – the study of bones
Endocrinology – the study of endocrine glands and hormones.
Neurology – the study of functioning of brain
Hematology – the study of blood.
Enzymology—the study of enzymes



Relation of Biology with other branches of Science

Biology has relationship with other branches of science. We can not study biology without the help of other sciences. We need the knowledge of other sciences to understand biology.
Relation of Biology with Chemistry
In side the cells as well as body of animals and plants there are inorganic substances and organic compounds.
Enzymes, hormones , vitamins and minerals are all chemicals. They take part in different vital activities.
The acid base balance maintains pH. It is required to carry out biological reactions in the body.
Chemical processes like diffusion, osmosis, plasmolysis, solubility play important role in biological system. These chemical processes help in absorption, excretion, filtration , ascent of sap, transpiration in animals and plants,
The electrolytes like Na + and K+ play role in conduction of nerve impulse in brain.
The subject Biochemistry shows the relation of Biology and Chemistry.

Relation with Physics
The bones and cartilages of body of animals provide the mechanical strength. They act as efficient levers with joints and muscle.
The lens of eye is for focusing light during image formation, ears are sensitive to change in sound waves.
Photobiology is related to the role of light in different biological processes like photosynthesis, photoperiodism, phototaxis and phototropism etc.
Use of energy and maintaining certain temperature of body.
The subject Biophysics shows the relation of Biology and Physics


Relation with Statistics and Mathematics
The researches in biology requires the knowledge of statistics and mathematics. Many interpretations in biology are based on the knowledge of statistics. The Mendelian ratio of monohybrid and dihybrid cross is the examples of relation of biology with statistics and mathematics.

Relation with Geography
Animals and plants are distributed at different regions of the earth. The north and south poles have similar climatic condition but only the south pole (Antarctica) has the Penguins. The polar bears are found only at the north poles. The Elephants are found only in Asia and Africa. This shows the relation of biology with the geography. It is called as Zoogeography or biogeography.

Biology as science of exception

Though there are different rules and regulations in the different branches of sciences, there are many exceptions in biology. So biology is called as the science of exceptions.
The red blood corpuscles(RBC) of mammals are without nucleus except Camels.
DNA is the hereditary materials in all except the Viruses.
The heart of reptiles are three chambered except the Crocodiles.
Fishes have gills for respiration but Protopterus (Nile lung fish) has lungs.
Larva develops into adult but American Salamander larva becomes sexually matured and gives birth to larva.
Birds are usually adapted for flying but certain birds like Kiwi, Ostrich can never fly.
Stems are usually aerial but ginger, potato have underground stem.
Mammals are viviparous but duck billed Platypus, Echidna is oviparous

General approach to understand life processes

The living beings have certain unified and basic characters by which they become different from non living things. Each and every living being is a complex entity which is made up of one or many cells. In the cells, there are different bio molecules. Micro molecules like water, salt, monosaccharide, amino acid etc and macro molecules like complex carbohydrate, protein and fats are present. The molecules interact, aggregate and participate in the vital activities of organisms. In this connection, Linus Pauling says that life results due to a relationship of molecules and not a property of any one molecule.

The life processes are given below

Nutrition -- it is the process of getting food. Green plants have chlorophyll. They can manufacture their food by the process known as photosynthesis. They are called autotrophs. Animals are not capable of synthesizing their food. They get their food either from plants or other animals. They are heterotrophs. The non green plants which take food from the dead bodies are called saprophytes.
Growth and metabolism-- plants and animals grow in their size. Plants grow in height indefinitely but animals grow in height for certain period. However there is growth all the time. It involves an increase in volume through the formation of new protoplasm with or without division of their structural units cells. Cells grow by addition of new protoplasm. This process of growth in living is called intussusceptions. It is irreversible. A crystal also grows but it is addition of new material at the surface. It is accretion. Metabolism is building up (anabolism) and breakdown ( catabolism) of body. It is a continuous process from birth to death.
Respiration – both animals and plants respire. They take O2 from atmosphere. They burn the food (glucose) to produce energy. It is aerobic respiration. The lower organism break down glucose with out O2 to produce energy. It is anaerobic respiration.
Excretion – the waste materials produced in side the body is discharged out. It is excretion. The lungs throw out CO2. The large intestine gives out undigested materials. The kidneys filter out the urea, uric acid etc. Animals discharges wastes as soon as possible. The plants can store in the part of body and throws after certain period. They also can use waste for mechanical strength.
Irritability and movement -- it is response to external or internal stimuli. Animals show quick response. The plants are slow to show the response. But there is rapid movement in insectivorous plants like Venus’s fly trap. In Mimosa (touch me not plant) the gentle pressure can make the folding of leaves.
Homeostasis - - it is the state of balance of salts, water, temp, pH etc. it is coordinating mechanism to keep the internal environment at steady or normal state.
Adaptability – all plants and animals are capable of undergoing certain changes in their structure, habit and habitat to become suitable to the environment. The fishes are adapted to live in water. Birds made them suitable to fly in air etc.
Evolution -- organisms under go changes in their genetic material. These changes are passed on to offsprings in succeeding generation. Such changes are raw material for evolution. This property of evolution is a function of population of organism and not in individual organism.
Reproduction -- they can produce their own kind. Since the living things eventually die, reproduction ensures survival of the group. Living organism come from pre existing living organism.
Ageing and death -- ageing is the process of deterioration of body. The efficiency of working decreases slowly and gradually. At the end, there is the death. The heart beat and respiration are arrested. Death helps to maintain certain number in population. The decomposers act on dead body to convert into C, H O, N,S etc. These are returned to the nature for balance.