FREE NEET Biology Practice MCQ Test: Human Reproduction Exercise 1 Questions Answers With Detailed Explanations [PDF]

Answer: (d)

Answer: (b)

Answer: (d)

Ovum contains the haploid set of chromosomes with one of the X chromosomes. The haploid set of chromosomes in the male gamete, sperm has either the X or Y chromosome. Thus, the sex of the foetus depends on the male gamete fertilizing the ovum.

Answer: (a)

Answer: (c)

Answer: (c)

The testes are situated outside the abdominal cavity within a pouch called scrotum. The scrotum helps in maintaining the low temperature of the testes (2– 2.5°C lower than the normal internal body temperature) necessary for spermatogenesis.

Answer: (b)

Spermatogenesis is initiated at puberty due to the increase in Gonadotropin Releasing Hormone (GnRH) by hypothalamus.

Answer: (d)

In human beings, ovum is released from the ovary in the secondary oocyte stage. The maturation of secondary oocyte is completed in the mother's oviduct (Fallopian tube) usually after the sperm has entered the secondary oocyte for fertilisation. Entry of the sperm restarts the cell cycle breaking down MPF (M-phase promoting factor) and turning on APC (Anaphase promoting complex). Completion of meiosis II converts the secondary oocyte into a fertilised ovum (egg) or zygote (and also a second polar body).

Answer: (a)

Spermatogenesis is the process of formation of haploid spermatozoa (sperms) from diploid spermatogonia inside the testes of the male. At sexual maturity, the undifferentiated primordial germ cells divide several times by mitosis to produce a large number of spermatogonia or sperm mother cells. Each spermatogonium actively grows to a larger primary spermatocyte by obtaining nourishment from the nursing cells. The phenomenon of formation of primary spermatocytes from spermatogonia, is called spermatocytogenesis. Each primary spermatocyte undergoes two successive divisions, called maturation divisions. The first maturation division is reductional or meiotic. Hence, the primary spermatocyte divides into two haploid daughter cells called secondary spermatocytes. Both secondary spermatocytes now undergo second maturation division which is an ordinary mitotic division to form four haploid spermatids, by each primary spermatocyte. The transformation of spermatids into spermatozoa is called spermiogenesis or spermateleosis or differentiation phase.

Answer: (c)

Answer: (a)

Sertoli cells are present in the germinal epithelium of the seminiferous tubules. These cells nourish the developing sperms. These cells differentiate spermatogonia into sperms. They are under the influence of FSH released by anterior pituitary gland.

Answer: (a)

Answer: (c)

The male sex accessory ducts include rete testis, vasa efferentia, epididymis and vas deferens. The seminiferous tubules of the testis open into the vasa efferentia through rete testis. The vasa efferentia leave the testis and open into epididymis located along the posterior surface of each testis. So if vasa efferentia gets blocked, the gametes will not be transported from testes to epididymis.

Answer: (c)

Answer: (d)

Answer: (b)

A-Interstitial cells, B-Spermatogonia, C-Spermatozoa, D-Sertoli cells. In the lining of seminiferous tubules, interstitial cells and sertoli cells are present.

Answer: (c)

Answer: (c)

During fertilization in humans, when many sperms reach close to the ovum, the secretion of acrosome helps the sperm to enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This induces the completion of the meiotic division of the secondary oocyte.

Answer: (a)

Answer: (b)