HEREDITY AND EVOLUTION– 2020 Important Questions


Q1. In any population, no two individuals are absolutely similar. Why?

Q2. What is the cause of variation in asexually reproducing organisms?

Q3. Give an example where sex is determined by environmental factors.

Q4. In a beetle population, the number of green beetles is more than blue and red beetles. Give a reason behind this situation.

Q5. Write one word for the formation of new species due to gradual change over long period of time.

Q6. Give an example of a characteristic being used to determine, what relationship do two species have in terms of evolution?

Q7.  What is a gene?

Q8.  What is heredity?

Q9. Give the respective scientific terms used for studying:

(i) the mechanism by which variations are created and inherited and,

(ii) the development of new type of organisms from the existing ones.

Q11.  What is speciation?

Q12. List any two factors that could lead to speciation?

Q13.  When does the process of gene flow take place?

Q14.  When is a recessive trait able to show up?

Q15.  Which among the males and females are homogametic?

Q16.  In which animals, the feathers do not fulfil the purpose of flying?

Q17.  Enumerate the functions of chromosomes.

Q18.  What is F2 -generation?

Q19. Genes and chromosomes have similar behaviour. Justify.

Q20. Among all the chromosomes, what is different about a sex chromosome?

Q21.  Give the role of genes in evolution.

Q22.  Name two important factors that cause development of a new species.

Directions (Q. Nos. 23 – 27) In the following questions, a statement of Assertion is followed by a statement of Reason. Mark the correct choice as

(a) If both Assertion and Reason are true, and Reason is the correct explanation of Assertion

(b) If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion

(c) If Assertion is true, but Reason is false

(d) If Reason is true, but Assertion is false

(e) If both Assertion and Reason are false

Q23. Assertion: Mendel self-crossed F1 tall plants with wrinkled seeds to obtain F2 generation.

            Reason: F1 progeny of a tall plant with round seeds and a dwarf plant with wrinkled. seeds are all dwarf plants having wrinkled seeds.

Q24.  Assertion: The experiences of an individual during its lifetime cannot be passed on to its progeny.

             Reason: Change in non-reproductive tissues cannot be passed on to DNA of germ cells.

Q25.  Assertion: Mendel choose pea plants for his experiment.

            Reason: Pea plants were the only plants he could gather for his experiment.

Q26.  Assertion: Evolution of also occurs by way for ‘Genetic Drift’.

             Reason: Genetic Drift leads to selection animals who have the most advantageous mutations.

Q27.  Assertion: Homologous and Analogous organs are method of tracing Evolutionary relationship.

             Reason: Homologous and Analogous organs are studied on the basis of fossils found in the Earth.

Q28. If pea plants having round green seeds and wrinkled yellow seeds are crossed, what phenotypic ratio will be obtained F2  progeny plants?

(a) 1: 2: 1             

(b) 3: 1                 

(c) 9: 3: 3: 1        

(d) 9: 3: 4

Q29. Section of DNA that provides information for one protein is called

(a) genotype        

(b) chromosome

(c) gene

(d) character

Q30.  An example of analogous organs is

(a) the wings of birds and bats

(b) our teeth and an elephant’s tusks

(c) potato and runners of grass

(d) our arm and dog’s foreleg.

Q31.  In human beings, the sex of child depends on whether the paternal chromosome is

(a) x (for boys) or Y (for girls)       

(b) X (for girls) or Y (for boys)

(c) present                                         

(d) absent


Q1.   In a   monohybrid cross, pink coloured flowers are dominant over white coloured flowers. If parent plants belong to pure breeding dominant trait and pure breeding recessive trait, what will be the phenotype or morphological feature of F1-generation? If F1 plants are self-fertilised, what would be the phenotypic ratio or how many dominant and recessive traits will be produced in the progeny? Explain with an illustration.

Q2.  Distinguish between acquired and inherited characters with an example of each.

Q3.  Traits that are acquired during lifetime do not result in evolution. Why?  Give atleast two examples to support your answer.

Q4.  The two areas of study namely ‘evolution’ and ‘classification’ are interlinked. Justify the statement.

Q5.  What are homologous structures? Give an example. Is it necessary that homologous structures always have a common ancestor?

Q6.  Mention three important features of fossils which help in the study of evolution.

Q7.  How do Mendel’s experiment show that traits are inherited independently?

Q8.  If we cross-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant, we will get plants of F1 generation. If we now self-cross the pea plant of F1 generation, we obtain pea plants of F2 generation.

(i) What do the plants of F1 generation look like?

(ii) State the ratio of tall plant to dwarf plants in F2 generation.

(iii) State the type of plants not found in F1generation but appeared in F2 generation. Write the reason for the same.

Q9. What is DNA copying? State Its Importance.

Q10. (i)  Name the unit of inheritance. What is its functions?

            (ii) How are inherited traits different from acquired traits? Give example.

Q11. (i) Define Genetics.

            (ii) Who is regarded as the ‘Father of Genetics’? Name the plant on which he performed his experiment.

            (iii) Why did he select that specific plant for his experiments?

Q12.  How did Mendel interpret his result to show that traits may be dominant or recessive? Describe briefly.

Q13. ‘Different species use different strategies to determine sex of a newborn individual. It can be environmental cues or genetically determined.’ Explain the statement by giving example for each strategy.

Q14.  A blue colour flower plant denoted by BB is crossbred with a white colour flower plant denoted by ww.

(i) State the colour of flower we would expect in their F1progeny.

(ii) Write the percentage of plants bearing white flower in F2 generation when the flowers of F1 plants were selfed.

(iii) State the expected ratio of the genotype BB: Ba: ww in the F2 progeny.

Q15. The genotype   of green-stemmed tomato plants is denoted   by GG and that of purple-stemmed tomato plants as gg. When these two plants are crossed:

(i) What colour of stem would you expect in their F1 progeny?

(ii) Give the percentage of purple-stemmed plant if F2 plants are self-pollinated.

(iii) In what ratio would you find the green and purple colour in the F1 progeny?

Q16. In Mendel’s monohybrid cross between tall and short pea plants, all offsprings were tall.  What does this tell us about the trait? What is the ratio of tall and short plants in the F2 generation?

Q17. What are chromosomes?   Explain how in sexually reproducing organisms the number of chromosomes in the progeny is maintained.

Q18.‘It is a matter of chance whether a couple will give birth to a male child or a female child’. Justify this statement with the help of a flow chart showing the fusion of sex chromosomes.

Q19.In human beings, the statistical probability of getting either a male or a female child is 50%. Give reasons and explain with the help of a diagram.

Q20. Explain the following: (a) Speciation (b) Natural Selection

Q21. ‘Natural Selection and Speciation leads to evolution’. Justify this statement.

Q22.  Explain with   an   example   for   each, how   the following    provides       evidences    in    favour    of evolution in organisms:

(i) Homologous organs

(ii) Analogous organs

(iii) Fossils

Q23. List three main factors responsible for the speciation and briefly describe each of them.

Q24. Define evolution. How does it occur? Explain how fossils provide evidences in support of evolution?

Q25. What are homologous organs? Give one example. Can the wings of a butterfly and the wings of bat be regarded as homologous? Give reason in support of your answers.

Q26. What are fossils? State their importance in the study of evolution with the help of a suitable example.

Q27. (i) Which   of the following fossil is invertebrate and which one is vertebrate?

(a) Dinosaur, (b) Ammonite.

          (ii) How can the age of fossil be ascertained? State in brief any two methods.

Q28. Give an example of the characteristics being used to determine how close two species are in evolutionary terms.

Q29.There are two different types of organs, homologous and analogous. Differentiate between them by giving three points.

Q30.‘Variations that confer an advantage to an individual organism only will survive in a population.’ Justify.

Q31. (i)  A husband has 46 chromosomes, his wife has also 46 chromosomes.  Then why don’t their offsprings have 46 pairs of chromosomes, which is obtained by the fusion of male and female gametes?

           (ii) “Geographical   isolation   is not a major factor in the speciation of a self-pollinating plant species.” Justify this statement with the help of an example.

Q32. What are heredity and variation?  Why did Mendel select garden pea plant to conduct his genetics experiments?

Q33. ‘Variations that confer advantage to an individual organism only will survive in population’. Justify.                                                                                                     

Q34. What does help scientists to reconstruct the pattern and trends that existed in the history of life on the Earth?

Q35.  What do you understand about independent inheritance of traits?

Q36.  A man having blood group ‘O’ marries a woman with blood group ‘B’.  What will be the blood group of their children?

Q37.  How are contributions of Darwin different from that of Mendel?

Q38.  How do homologous organs help in determining the evolutionary trend?


Q1.         ‘A trait may be inherited, but may not be expressed’. Justify this statement with the help of a suitable example.

Q2.         Define evolution.  How does it occur? Describe, how fossils provide us evidences in support of evolution.

Q3.         Name any five vegetables generated from a common ancestor through artificial selection rather than natural selection. Also mention the features for which each vegetable is selected?           

Q4.         Does geographical isolation of individuals of a species lead to formation of a new species? Provide a suitable explanation.

Q5.         Why is it more appropriate to compare the process of evolution with’ branches of a tree rather than with a ladder?

Q6.         How did Mendel explain that it is possible that a trait is inherited but not expressed in an organism?

Q7.         (i) What is meant by traits of an individual?

                 (ii) Explain inherited trait and acquired trait.

                 (iii) Define speciation.  List the factors which could lead to rise of a new species.

 Q8. (i) Explain whether traits like eye colour or height is genetically inherited. Do power to lift weights and reading  French also belong to the same category?

        (ii) How do variations affect the evolution of those organisms that reproduce sexually?

Q9. Name the phenomenon that governs the following:

(i) Green beetles living in green bushes are not eaten by the crows.

(ii) Number of blue beetles in green bushes increases only because the red beetles, living there, were trampled by a herd of elephants.

(iii) No ‘medium height plants’ are obtained in F1 generation, upon crossing pure tall and dwarf pea plants.

(iv) Tails of mice were surgically removed for several generations, still mice had tails in the following generations.

(v) A migrant beetle reproduces with the local population; as a result, genes of migrant beetle enter the new population.

Q10. What are fossils? How are they formed? List two methods of determining the age of fossils. Explain in brief the importance of fossils in deciding the evolutionary relationships.

Q11. (a)  What are fossils and how is age of fossils determined?

            (b) During artificial selection, which features of wild cabbage were selected to give rise to

(i) Cabbage and

 (ii) Cauliflower

Q12.  Ovum and sperm are both female and male gametes, respectively. But what is so intricate in sperm which makes it solely responsible for determining the sex of the child? Explain.

Q13. Define the following.

 (a) Speciation

(c) Recessive trait

(e) Genetics

 (b)  Genetic drift

(d) Evolution

Q14.       How does comparing DNA of different species help in tracing evolutionary relationship?


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