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
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)