Grade 11 Zoology Note

Introduction To Biology

Nature and scope of Biology:

Biology: Biology is a branch of science which deals with the living beings whereas other branch of science is called physical science deals with physic, chemistry, math, meterology, etc.

                   The word biology is coined by two great scientists, John Baptist deLamarch and Trevivanusin 1802. In Biology which deals with the study of plants called botany and deals with the animals called zoology.

            The father of botany was Theophrastus (370 – 287 B.C). Similarly father of zoology, embryology and founder of taxonomy was great philosopher Aristotle (384-322 B.C).

Scope of Biology:

                    Biological members such as plants and animals have been utilizing in various fields because of their importance. The major or importance or scope of biology is as follows:

1. Economic value

2. Food value

3. Medicinal value

4. Research value

5. Industrial value

6. Ecological value

7. Aesthetic value

8. Game value

   Branch and relation with other sciences:

1. Morphology: Study of external form and structure of living organism is called morphology.

2. Anatomy: Study of internal structure of plants and animals.

3. Histology: Study of details of tissues structure of organisms.

4. Psychology: The study of human behavior and mental quality.

5. Paleontology: The study of extinct and fossils organisms.

6. Mycology: Study of fungi.

7. Phycology: Study of algae.

8. Bryology: Study of liverworts and mosses.

9. Helminthology: Study of worms/ helmints.

10. Parasitology: Study of parasitic organisms.

11. Entomology: Study of insects.

12. Ornithology: Study of birds.

13. Mammalogy: Study of mammals.

14. Herpetology: Study of reptiles and amphibians

15. Protozoology: Study of one – celled animals.

16. Zoology: Study of animals.

17. Botany: Study of plants.

18. Icthyology : Study of fishes.

19. Evolution: Study of origin.

20. Embroyology: Study of embryos.

21. Pollynology : Study of pollen grains.

22. Pteridology: Study of pteridophytes.

23. Cardiology: Study of heart.

24. Neurology: Study of neurons.

25. Virology: Study of virus.

26. Ethology: Study of animal behaviour.

27. Ethnology: Study of different rules mankind in different distribution.

28. Eugenics: Study of improvement of races.

29. Cytology: Study of cells.

30. Protozoalogy: Study of protozoans.

Relation of Biology with other Science:

Relation with Chemistry:

1. Body of all living organisms s made up of organic and inorganic compounds.

2.All the metabolic activities inside the body of living beings involve chemical reactions and chemical changes.

3.Genetic materials DNA and RNA are also chemicals.

4.Enzymes and hormones produced in the body of living organisms are also exclusively chemicals.

5.Acid-base equilibrium in a cell maintains the pH of the protoplasm for proper functioning.

6.Molecules move in and out of the cells by diffusion and osmosis.

Relation with Physics:

1.Biological instruments such as microscopes, X-rays, ECG etc. are based on the principles of physics.

2.Light induces various effects on living organisms.

3.Study on the structure and functioning of human eye require knowledge of optics.

4.Physical techniques such as: electron microscopy, X-ray diffraction, fractionation, Chromatography etc. have made possible the study of finer details of cellular and sub-cellular components.

Relation with Geography:

Distribution of plants and animals vary different geographical factors. e.g.  Climate, altitude, temperature etc.

Relation with Mathematics and Statistics:

Census of wild animals is based on application of mathematical and statistical applications. Such applications are helpful in data compilation and analysis of living organisms.

Relation with Sociology:

Study of human behavior, social relationship and antisocial relationships needs idea of biological science. For example, investigation on criminals and terrorists requires the study of human nervous system and study of glands, hormones, etc. It also requires the knowledge of principles of inheritance, pedigree analysis, etc.

Life Process of Living Beings:

       Living beings totally differs from non-living beings in having various life processes such as;

1.Respiration: It is defined as the process for releasing energy in the form of ATPs.

Steps of respiration:

A) External respiration:

a. Breathing

b. Exchange of gases

B) Internal respiration:

a. Oxidation of food

b. Release of energy

Types of respiration:

a. Aerobic

b. Anaerobic

Aerobic Respiration


Anaerobic Respiration


a.Respiration occurs in presence of oxygen.

a. Respiration occurs in absence of oxygen.

b. released more energy.

b. released less energy

c. It is very common.

c. It is rare and it is mainly shown by prokaryotic organism.

d. by products:

CO₂ + H₂O +E

d. by products:

C₂H₅OH +CO₂ +H₂O +E


 Plants and animals respire in similar ways but only differs in definite respiratory organs found only in the animals not in the plants.


       It is a part of physiological process related with food in which complex food simplifies into absorbable food. After absorption utilizes during body growth, body metabolic activities, physical or chemical activities, synthesis of enzymes and hormones, change worn out body portion and give energy, etc. Based upon the nature of the foods, nutrition classified into three types:

a. Autotrophic nutrition: It is shown by all kinds of green organism such as green plants. They manufactured food by themselves through the process of photosynthesis. So it is called as non- dependable organism.

b. Chemotrophic nutrition: It is shown by primitive organism like bacteria which depends upon the chemicals as the source of their food. Eg; N₂ fixative bacteria food (NO₃ compound)

c. Heterotrophic nutrition: It is shown by all kinds of animals. They depends upon the others as the source of the food. The sub types of heterotrophic are;

a. Holozoic nutrition

b. Holophytic nutrition

c. Saprozoic nutrition

d. Saprophytic nutrition

e. Parasitic nutrition

3. Adaptations:

        Any change in an organism that makes it slowly or rapidly better suited to its environment is called adaptation. The adaptation may be short term or long term.

Short term Adaptations:

a. The human skin becomes dark on exposure to sunlight for a long time. This is because of the accumulation of melanin pigments in the top layer of the skin.

b. Dormant seeds suspend their metabolic activities during dormant period. In favorable conditions, dormancy is broken and the seeds germinate.

Long term Adaptations:

a. Thick tail of kangaroo is used as a fifth limb to support the body weight.

b. The ankles bones of humans protrude backwards and help stand erect.

c. The limbs bones of horses and deer are modified for swift running.

4. Death:

 It is an inherent part of an organism’s life cycle. The period from birth till death is called life span. Ageing may be defined as deterioration in structure and function of the body cells, tissues and organs of an animal.

Significance of death:

a. Death maintains the number of individuals in a population. It is necessary because of the limitation of food and space.

b. The dead and decaying body of organisms is decomposed by microbes. They decomposed the complex organic compounds into simple inorganic forms. These are returned into environment and maintain the ecological balance.

Importance roles of Death Cells:

 a. Dead cuticle layer of leaves check transpiration.

b. In plants dead xylem vessels act as channels for conduction of water and minerals.

c. Dead tissues in animals like nails, horns, hooves, down feathers provide support and protection.

d. Dead tissues in plants like heartwood, cork, provide strength and support.

5. Levels of organization.

6. Molecular basis of life.

7. Organisms show metabolism.

8. Movement

9. Organism reproduces.

Difference between:



1. Plant cell generally contains vacuoles.

Vacuole is generally absent in animal cell.

2. Usually starch is the reserve food material in plant.

2. Glycogen is the general storage food material in animal.

3. Sense organs and nervous system are lacking.

3. Sense organs and nervous system are present.

4. In plant cell RBCs are lacking.

4. In animals circulation of RBCs takes place.


Biology is a science of exception:

1. Euglena shows both plant and animals characters. It lacks cell wall but bears chloroplast.

2. Virus is a living organism but it lacks the cellular organization.

3. DNA is double stranded whereas in bacteriophage it is single stranded.

4. Mangroves produce respiratory roots which grow towards light against gravity.

5. Animals must become adults to reproduce but larval stages of salamander can reproduce.

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