HEREDITY AND EVOLUTION – 3 Mark Questions

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?

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