NCERT Class 10 Science Heredity and Evolution Answers

Multiple Choice Questions
1. (c) 2. (b) 3. (a) 4. (d)
5. (a) 6. (c) 7. (b) 8. (b)
9. (b) 10. (a) 11. (b) 12. (c)
13. (a) 14. (b) 15. (a) 16. (c)
17. (a) 18. (b) 19. (c) 20. (a)
21. (b) 22. (c) 23. (a) 24. (b)
25. (d)

Short Answer Questions

26. The sex of the individual is genetically determined i.e., genes inherited from parents decide whether the new born will be a boy or a girl. A new born who inherits an ‘X’ chromosome from father will be a girl and one who inherits a ‘Y’ chromosome will be a boy. 7. No, because mothers have a pair of X-chromosomes. All children will inherit an ‘X’ chromosome from their mother regardless of whether they are boys or girls.

28. (a) Fossils represent modes of preservation of ancient species.
(b) Fossils help in establishing evolutionary traits among organisms and their ancestors.
(c) Fossils help in establishing the time period in which organisms lived.

29. Human females have two X chromosomes called sex chromosomes. During meiosis at the time of gamete formation, one X chromosome enters each gamete. Hence all the gametes possess an X chromosome.

30. The sex of an infant is determined by the type of sex chromosome contributed by the male gamete. Since the ratio of male gametes containing X chromosome and those containing Y chromosome is 50 : 50, the statistical probability of male or a female infant is also 50 : 50.

Please refer to attached file for NCERT Class 10 Science Heredity and Evolution  Answers