How do Organisms Reproduce: Class 10 Important Questions with Answers

Case-based questions (4 marks each)

(i) Name the mode used for roses and grapes. (1) (ii) Give two advantages of this mode. (1) (iii) Name the laboratory technique and write its steps. (2)

(i) Name the alga and its mode of reproduction. (1) (ii) Name the bread mould and what the black dots are. (1) (iii) Why did the mould spread so fast, and how are spores protected? (2)

(i) What role do the bees play? Name the process. (1) (ii) Trace the path of the pollen tube. (1) (iii) What do the ovary and ovules become, and why do the petals fall? (2)

(i) Name the hormone causing puberty changes in girls and its gland. (1) (ii) Why does menstruation occur? (1) (iii) Name one STD each caused by bacteria and by viruses. Which contraceptive also protects against STDs, and why? (2)

20 MCQs (1 mark each)

1. The information for inheritance is carried by
   (a) protein (b) DNA (c) lipid (d) sugar
2. Leishmania causes
   (a) malaria (b) kala-azar (c) typhoid (d) AIDS
3. Multiple fission occurs in
   (a) Amoeba (b) Plasmodium (c) Leishmania (d) yeast
4. Spirogyra reproduces by
   (a) budding (b) fragmentation (c) spores (d) fission
5. Regeneration is seen in
   (a) Planaria (b) Plasmodium (c) Rhizopus (d) yeast
6. Buds in leaf notches are found in
   (a) money plant (b) Bryophyllum (c) rose (d) potato
7. The mass of cells in tissue culture is called
   (a) zygote (b) callus (c) embryo (d) spore
8. In Rhizopus, spores are produced in
   (a) hyphae (b) sporangia (c) rhizoids (d) buds
9. Gametes have
   (a) double (b) half (c) the same (d) no chromosomes compared to body cells
10. The male reproductive part of a flower is the
    (a) pistil (b) stamen (c) sepal (d) petal
11. Ovules are present in the
    (a) anther (b) stigma (c) ovary (d) style
12. After fertilisation the ovary becomes
    (a) seed (b) fruit (c) embryo (d) flower
13. Future shoot of the embryo is the
    (a) radicle (b) plumule (c) cotyledon (d) testa
14. Papaya flowers are
    (a) bisexual (b) unisexual (c) both (d) none
15. Sperms are formed in the
    (a) prostate (b) testes (c) vas deferens (d) urethra
16. Fertilisation in humans occurs in the
    (a) uterus (b) ovary (c) fallopian tube (d) vagina
17. The embryo is nourished through the
    (a) placenta (b) ovary (c) cervix (d) oviduct
18. Menstruation lasts about
    (a) 1 day (b) 2–8 days (c) 14 days (d) 28 days
19. Vasectomy means blocking the
    (a) fallopian tube (b) urethra (c) vas deferens (d) ureter
20. A viral STD is
    (a) gonorrhoea (b) syphilis (c) warts (d) tuberculosis

Answer key

Assertion–Reason (10)

(a) Both A and R true, R explains A · (b) Both true, R does not explain A · (c) A true, R false · (d) A false, R true

1. A: DNA copies made during reproduction are not identical. R: No biochemical reaction is absolutely reliable. → (a)
2. A: Variation is always useful for an individual. R: Variation helps a species survive changes in its niche. → (d)
3. A: Human populations show a great deal of variation in traits. R: All variations in a species have equal chances of surviving. → (c)
4. A: Testes are located outside the abdominal cavity. R: Sperm formation needs a lower temperature than the body temperature. → (a)
5. A: Banana is grown by vegetative propagation. R: Banana has lost the capacity to produce seeds. → (a)
6. A: Regeneration is the same as reproduction. R: Planaria pieces grow into new individuals. → (d)
7. A: Gametes have half the number of chromosomes. R: Gametes are formed by meiosis. → (a)
8. A: Petals are brightly coloured. R: Petals contain the ovules. → (c)
9. A: Copper-T prevents pregnancy. R: Copper-T protects against STDs. → (c)
10. A: Placenta allows glucose and oxygen to pass to the embryo. R: Placenta has villi giving a large surface area. → (a)

Give reasons (2 marks each)

1. Complex organisms cannot reproduce by fission.

Their cells are organised into tissues and organs at definite positions; cell-by-cell division cannot rebuild such an organised body. 2

2. Sexual reproduction produces more variation.

It combines DNA from two different individuals, each with its own accumulated variations, giving new combinations. 2

3. The uterus lining thickens every month.

To receive and nourish a fertilised egg (embryo) with a rich blood supply, in case fertilisation occurs. 2

4. Prenatal sex determination is banned.

It is misused for female foeticide; this lowers the female–male sex ratio, harmful for a healthy society. 2

5. Rhizopus spores have thick walls.

To protect them from harsh conditions until they reach a moist surface where they can grow. 2