CBSE - Biology - How do Organisms Reproduce?

16. Which of the following statements are true for flowers?
(i) Flowers are always bisexual
(ii) They are the sexual reproductive organs
(iii) They are produced in all groups of plants
(iv) After fertilisation they give rise to fruits
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (ii) and (iv)
Ans. (d) (ii) and (iv)
Explanation: Some flowers are unisexual and hence statement (i) is incorrect. Flowers are produced by angiosperms only and hence statement (iii) is incorrect.

17. Which among the following statements are true for unisexual flowers?
(i) They possess both stamen and pistil
(ii) They possess either stamen or pistil
(iii) They exhibit cross pollination
(iv) Unisexual flowers possessing only stamens cannot produce fruits
(a) (i) and (iv)
(b) (ii), (iii) and (iv)
(c) (iii) and (iv)
(d) (i), (iii) and (iv)
Ans. (b) (ii), (iii) and (iv)
Explanation: Since a unisexual flower has either stamen or pistil, hence cross pollination is necessary in them. Fruit is a mature ovary and hence a flower possessing only stamens cannot produce fruit.

18. Which among the following statements are true for sexual reproduction in
flowering plants?
(i) It requires two types of gametes
(ii) Fertilisation is a compulsory event
(iii) It always results in formation of zygote
(iv) Offspring formed are clones
(a) (i) and (iv)
(b) (i), (ii) and (iv)
(c) (i), (ii) and (iii)
(d) (i), (ii) and (iv)
Ans. (c) (i), (ii) and (iii)
Explanation: Offspring produced after sexual reproduction are never clones of their parents. Hence, statement (iv) is incorrect.

19. In Figure 8.1, the parts A, B and C are sequentially

(a) cotyledon, plumule and radicle
(b) plumule, radicle and cotyledon
(c) plumule, cotyledon and radicle
(d) radicle, cotyledon and plumula
Ans. (c) Plumule, cotyledon and radicle
Explanation:

20. Offspring formed as a result of sexual reproduction exhibit more variations because
(a) sexual reproduction is a lengthy process
(b) genetic material comes from two parents of the same species
(c) genetic material comes from two parents of different species
(d) genetic material comes from many parents
Ans. (b) genetic material comes from two parents of the same species
Explanation: In sexual reproduction, genetic materials are contributed by two parents.
Members of two different species cannot interbreed and hence option �c� is incorrect.
21. Reproduction is essential for living organisms in order to
(a) keep the individual organism alive
(b) fulfill their energy requirement
(c) maintain growth
(d) continue the species generation after generation
Ans. (d) continue the species generation after generation
Explanation: Other life processes are essential for keeping the organism alive. Reproduction is essential to continue the lineage of an organism.

22. During adolescence, several changes occur in the human body. Mark one change
associated with sexual maturation in boys
(a) loss of milk teeth
(b) increase in height
(c) cracking of voice
(d) weight gain
Ans. (c) cracking of voice
Explanation: Other changes; as shown in options happen in girls also.

23. In human females, an event that reflects onset of reproductive phase is
(a) growth of body
(b) changes in hair pattern
(c) change in voice
(d) menstruation
Ans. (d) Menstruation
Explanation: Other changes; as shown in options happen in boys also.

24. In human males, the testes lie in the scrotum, because it helps in the
(a) process of mating
(b) formation of sperm
(c) easy transfer of gametes
(d) all the above
Ans. (b) Formation of sperm
Explanation: The fact that testes lie in the scrotum ensures that the temperature of testes is below body temperature. It ensures optimum production of sperms.

25. Which among the following is not the function of testes at puberty?
(i) formation of germ cells
(ii) secretion of testosterone
(iii) development of placenta
(iv) secretion of estrogen
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
Ans. (c) (iii) and (iv)
Explanation: These events take place in females and not in males. Testes are present in males.

26. The correct sequence of organs in the male reproductive system for transport of
sperms is
(a) testis → vasdeferens →urethra
(b) testis →ureter →urethra
(c) testis →urethra →ureter
(d) testis →vasdeferens →ureter
Ans. (a) testis →vasdeferens →urethra
Explanation: Ureter is connected to kidneys only.

27. Which among the following diseases is not sexually transmitted?
(a) Syphillis
(b) Hepatitis
(c) HIV - AIDS
(d) Gonorrhoea
Ans. (b) Hepatitis
Explanation: It is a water-borne disease.