1.HEREDITY: Transmission of features or characters from one generation to another or from parents to offspring through their genes

2.VARIATION: It occurs due to sexual reproduction, inaccuracies during DNA replicating (mutation) and due to environmental factors.

3.GENETICS: Branch of biology dealing with the study of heredity and variations.

4.ALLELES :There is one pair of alleles which can express itself whether present in homozygous state or heterozygous state. Eg – T (tallness in pea plant), R(round seeds in pea plant)

5.GREGOR JOHANN MENDEL:- (1822-1884): He is known as the father of ‘genetics’. He worked on Sweet pea plant(pisum sativum).

6.GENOTYPE: genetic composition of an individual, eg – pure tall-TT, hybrid tall-Tt

7.PHENOTYPE: Visible traits of an individual. Eg – Tallness or Dwarfness.

8.EVOLUTION: gradual changes in traits of organisms from pre existing organisms is called evolution.

9.SPECIATION: It may take place when variation is combined with geographical isolation. (Formation of new species)




1.The number of chromosomes in human ovum is

a.21 b.22 c.23 d.24

2. An example of homologous organs is

a.our arm and a dog’s foreleg b./our seethe and an elephant’s tusk

c.potato and runners of glans. D. all of these.

3. The hereditary units are:

a. Segments of RNA b. Genes. c. Chromosomes f. Chromatin

4. The science dealing with biotechnology is called.

a.Heredity and variation b. paleontology c. genetics


1.If a trait exists in 10% of a population of an asexually reproducing species and a trait B in 60% of the same population which trait is likely to have arisen earlier?

2.Which of the following is not the example of artificial selection ?

A)Colours of rose b.Flavours of mangoes 3.colours of beetle 4.Starch quality of wheat.

3. Explain how advantages variations like long neck help an organism like Giraffe to survive better?

4. Which of the following is the clearly acquiered trait in human beings?

a.Intelligence b.Height C.Swimming d. Skin colour.

5. Why are human beings, who look different from each other size and colour belongs to the same species?

6. Acquiered characters are not inherited .Give reasons.

7. All the human races like Africans, Asians ,European and others might have from common ancestors provide few evidence in support of the view.

8. How is genetic drift different from natural selection? From the diagram given below which case shows natural selection?

Refer to diagram 9.7 ,page 147 of textbook.

9.Observe the diagram properly, mention the ration of round, yellow seeds and wrinkled,green seeds. Refer to diagram 9.5,page 145 of text book.

10.From the figures given below ,make a pair of homologous and analogous organs.Also justify the answer. Refer to page 132, diagram 9.8.



A. Decomposers are also called __________

B. Producers prepare their _____________

C. Ozone layer is destroyed by ___________

D. Ecology is the study of the interaction of_________ with each other and their surroundings.


A. Mendel’s work

B. Sex determination in organisms

C. Role play

D. Student in act as Aristotle ,Darwin,Lemark and Mendel and present the work done by these great people.


If Mendel had met!

Projects: 1. Save Tiger….. Children collect information about the Tigers from various national Parks and Wild life sanctuaries. Perform the stage shows to develop the awareness about the forests and wild life.

3. To collect information on artificial selection carried out in some crops and animals . Visit to Vetenary college.

4. Visit to an agricultural research Institute to understand the various techniques involved in Hybridisation.

5. 1.Conducting a survey on

A. Evolution of wisdom teeth in parents.

B. Free and attached earlobes.

C. Rolling of tongue.

D. Finger prints.

Debate: Use of Biotechnology in Human Welfare .

Activity; To study vestigial organs in Human beings . Students define vestigial organs and discuss the use of every part of the body.Then come to the conclusion.

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