Human Reproduction: Class 12 Important Questions with Answers

Practice set: test yourself

Try every question before looking at the answers below. 64 or more out of 80 means you are ready for the board.

C. Very short answer (1 mark each)

1. Name the duct from epididymis to ejaculatory duct.
2. Number of chromosomes in a spermatid.
3. Name the layer of uterus that contracts during delivery.
4. Name the finger-like projections of the infundibulum.
5. Where is the acrosome located?
6. Name the hormone surge that causes ovulation.
7. What is the inner cell mass?
8. Which hormone is produced by the ovary late in pregnancy?
9. Name the cells released with the secondary oocyte at meiosis I.
10. Which antibody is rich in colostrum?

D. Short answer I (2 marks each)

1. Distinguish between spermiogenesis and spermiation.
2. Why are testes located in the scrotum?
3. Give two differences between spermatogenesis and oogenesis.
4. How is polyspermy prevented?
5. What happens to the corpus luteum if fertilisation does not occur?
6. Name the three germ layers and state the fate of the inner cell mass.
7. Give two functions of the placenta.
8. Why is the follicular phase called the proliferative phase?

E. Short answer II (3 marks each)

1. Draw a labelled diagram of a seminiferous tubule section.
2. Trace the path of sperms from the seminiferous tubule to the outside.
3. Describe the role of hormones in spermatogenesis.
4. Describe the events of the luteal phase.
5. Explain how the sex of a baby is determined.
6. Explain the foetal ejection reflex.

F. Long answer (5 marks each)

1. Describe oogenesis from the foetal stage to fertilisation, with a schematic diagram.
2. Describe the events from fertilisation to implantation, and the formation of the placenta.

G. HOTS (higher-order thinking)

1. Why does a woman not ovulate during pregnancy?
2. Why is the first polar body much smaller than the secondary oocyte?
3. A man has normal sperm count but none are motile. Which part of the sperm may be defective?
4. Why can stem cells of the inner cell mass give rise to all tissues?

20 MCQs

1. Number of lobules in each testis
   (a) 100 (b) 500 (c) 250 (d) 50
2. Cells that nourish germ cells
   (a) Sertoli cells (b) Leydig cells (c) spermatogonia (d) granulosa
3. Seminal plasma is rich in
   (a) glucose (b) lactose (c) sucrose (d) fructose
4. Number of chromosomes in a secondary spermatocyte
   (a) 46 (b) 23 (c) 44 (d) 92
5. LH acts on
   (a) Sertoli cells (b) Leydig cells (c) spermatids (d) epididymis
6. The middle piece of the sperm contains
   (a) acrosome (b) centrioles only (c) nucleus (d) mitochondria
7. Primary oocytes are arrested in
   (a) prophase I (b) metaphase II (c) anaphase I (d) telophase II
8. The antrum appears in the
   (a) primary follicle (b) corpus luteum (c) tertiary follicle (d) oogonium
9. Ovulation occurs on about day
   (a) 5 (b) 28 (c) 21 (d) 14
10. Progesterone is secreted mainly by
    (a) Graafian follicle (b) corpus luteum (c) pituitary (d) hypothalamus
11. The proliferative phase is under the control of
    (a) progesterone (b) oxytocin (c) oestrogen (d) relaxin
12. Site of fertilisation
    (a) ampullary region (b) uterus (c) cervix (d) vagina
13. The embryo with 8–16 blastomeres
    (a) blastocyst (b) morula (c) gastrula (d) zygote
14. The outer layer of the blastocyst
    (a) inner cell mass (b) endoderm (c) trophoblast (d) chorion only
15. Which is not secreted by the placenta?
    (a) hCG (b) oestrogen (c) hPL (d) relaxin
16. First movements of the foetus are noticed in
    (a) 5th month (b) 2nd month (c) 8th month (d) 1st month
17. Oxytocin for parturition comes from
    (a) maternal pituitary (b) foetal pituitary (c) placenta (d) ovary
18. Colostrum contains antibodies of class
    (a) IgE (b) IgD (c) IgM (d) IgA
19. Meiosis II of the oocyte is completed
    (a) at ovulation (b) at sperm entry (c) at puberty (d) in the foetus
20. The sex of the baby is decided by
    (a) the ovum (b) the placenta (c) the sperm (d) hormones of the mother

1 (c) · 2 (a) · 3 (d) · 4 (b) · 5 (b) · 6 (d) · 7 (a) · 8 (c) · 9 (d) · 10 (b) · 11 (c) · 12 (a) · 13 (b) · 14 (c) · 15 (d) · 16 (a) · 17 (a) · 18 (d) · 19 (b) · 20 (c)

Assertion–Reason (6)

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

1. A: Testes are placed outside the abdominal cavity in the scrotum. R: Spermatogenesis needs a temperature 2–2.5 °C below body temperature.
2. A: One primary oocyte gives only one ovum. R: Both meiotic divisions of oogenesis are unequal.
3. A: Menstruation does not occur during pregnancy. R: The corpus luteum persists and keeps secreting progesterone.
4. A: Androgens are secreted by Sertoli cells. R: Leydig cells lie between the seminiferous tubules.
5. A: Fertilisation occurs in the uterus. R: The ampulla is the widest part of the oviduct.
6. A: The hymen is a reliable sign of virginity. R: It may tear during sports or cycling.

Key: 1 (a) · 2 (a) · 3 (a) · 4 (d) · 5 (d) · 6 (d)

Answers to the practice set