NEET Biology Human Reproduction MCQs Set 33

Answer: (b) pelvic region

Explanation:
1. The male reproductive system lies in the pelvic region.
2. It includes a pair of testes, accessory ducts, glands and the external genitalia.

Teacher's Note:
1. The testes lie outside the abdominal cavity in the scrotum.
2. The rest of the system is within the pelvis.

Answer: (b) 2-2.5°C

Explanation:
1. The scrotum keeps the testes at 2-2.5°C below body temperature.
2. This lower temperature is needed for spermatogenesis.

Teacher's Note:
1. Failure of the testes to descend (cryptorchidism) causes sterility.

Answer: (b) 4-5 cm and 2-3 cm

Explanation:
1. Each testis is about 4 to 5 cm long and 2 to 3 cm wide.

Teacher's Note:
1. Testes are the primary sex organs of the male.

Answer: (b) Leydig cells

Explanation:
1. Interstitial or Leydig cells lie between seminiferous tubules and secrete testosterone and other androgens.
2. They respond to LH.

Teacher's Note:
1. Androgens control male secondary sexual characters and spermatogenesis.

Answer: (a) ii - iv - iii - i

Explanation:
1. Sperms pass from seminiferous tubules to rete testis, then through vasa efferentia into the epididymis.
2. From the epididymis they go to the vas deferens.

Teacher's Note:
1. Sequence: seminiferous tubules, rete testis, vasa efferentia, epididymis, vas deferens.

Answer: (a) foreskin

Explanation:
1. The enlarged end of the penis, the glans, is covered by a loose fold of skin called the foreskin (prepuce).

Teacher's Note:
1. Circumcision is the removal of the foreskin.

Answer: (a) bulbourethral glands

Explanation:
1. Accessory glands are paired seminal vesicles, a single prostate and paired bulbourethral (Cowper's) glands.
2. Their secretions form the seminal plasma.

Teacher's Note:
1. Bulbourethral glands lubricate the penis.
2. Bartholin's glands belong to the female system.

Answer: (c) Primary spermatocytes are diploid

Explanation:
1. A primary spermatocyte has 46 chromosomes, so it is diploid, and it completes meiosis I.
2. Secondary spermatocytes are haploid and undergo meiosis II, and spermatogenesis begins only at puberty.

Teacher's Note:
1. Meiosis I makes haploid secondary spermatocytes from diploid primary spermatocytes.

Answer: (b) spermiogenesis

Explanation:
1. The conversion of spermatids into sperms is spermiogenesis.
2. The release of sperms from the seminiferous tubules is spermiation.

Teacher's Note:
1. Do not confuse spermiogenesis (formation) with spermiation (release).

Answer: (b) spermiation

Explanation:
1. After spermiogenesis, sperm heads are embedded in Sertoli cells and are finally released into the lumen by spermiation.

Teacher's Note:
1. Spermiation occurs before the sperms enter the epididymis.

Answer: (a) a significant increase in the secretion of GnRH

Explanation:
1. At puberty GnRH secretion rises sharply.
2. GnRH stimulates the anterior pituitary to release LH and FSH, which start spermatogenesis.

Teacher's Note:
1. Hypothalamus secretes GnRH, pituitary secretes LH and FSH.

Answer: (b) Sertoli; spermiogenesis

Explanation:
1. FSH acts on Sertoli cells, which secrete factors that help in spermiogenesis.
2. LH acts on Leydig cells.

Teacher's Note:
1. FSH works on Sertoli cells and LH works on Leydig cells.

Answer: (b) haploid nucleus

Explanation:
1. A sperm is a haploid gamete, so its head contains a haploid nucleus.
2. The acrosome covers the anterior part of the nucleus.

Teacher's Note:
1. Sperms have 23 chromosomes.

Answer: (b) fertilisation of the ovum

Explanation:
1. The acrosome contains hyaluronidase and other enzymes that dissolve the egg membranes.
2. This allows the sperm to enter the ovum.

Teacher's Note:
1. The acrosome is formed from the Golgi complex of the spermatid.

Answer: (a) epididymis, seminal vesicle and prostate

Explanation:
1. The epididymis, seminal vesicles and prostate secrete substances needed for sperm maturation and motility.
2. Sperms are stored in the epididymis.

Teacher's Note:
1. Seminal plasma is rich in fructose, calcium and some enzymes.

Answer: (a) seminal plasma

Explanation:
1. The seminal plasma from the accessory glands mixes with sperms to form semen.

Teacher's Note:
1. Seminal plasma supplies nutrients and a medium for transport.

Answer: (c) vas deferens

Explanation:
1. The vas deferens is part of the male system.
2. Ovary, oviduct, uterus, cervix, vagina and hymen are female structures.

Teacher's Note:
1. The vas deferens carries sperm from the epididymis to the urethra.

Answer: (a) primary

Explanation:
1. Ovaries are primary sex organs because they produce ova and the steroid hormones (oestrogen and progesterone).

Teacher's Note:
1. Uterus and oviducts are accessory sex organs.

Answer: (b) 2-4 cm long

Explanation:
1. Each human ovary is about 2 to 4 cm in length.
2. The statement of 5-8 cm is incorrect.

Teacher's Note:
1. Ovaries lie on each side of the lower abdomen.

Answer: (b) cortex; medulla

Explanation:
1. The stroma has a peripheral cortex that contains follicles and an inner medulla of connective tissue, blood vessels and nerves.

Teacher's Note:
1. Follicles develop in the cortex.

Answer: (b) an inverted pear

Explanation:
1. The uterus is pear-shaped (inverted pear) and is also called the womb.
2. It opens into the vagina through the cervix.

Teacher's Note:
1. The uterus is single and is supported by ligaments.

Answer: (b) myometrium

Explanation:
1. The myometrium is a thick layer of smooth muscle that contracts strongly during parturition.
2. The endometrium is the layer that sheds in menstruation.

Teacher's Note:
1. Oxytocin stimulates strong contractions of the myometrium.

Answer: (c) fimbriae

Explanation:
1. Fimbriae are part of the oviduct (internal).
2. Mons pubis, labia and hymen are external.

Teacher's Note:
1. Fimbriae are fringe-like extensions of the infundibulum.

Answer: (a) a-iii, b-iv, c-ii, d-i

Explanation:
1. Mons pubis is a cushion of fatty tissue: a-iii.
2. Labia majora are fleshy folds: b-iv.
3. The clitoris is a tiny finger-like structure: c-ii.
4. Labia minora are paired thin folds of tissue: d-i.

Teacher's Note:
1. Labia majora are outer, labia minora are inner.

Answer: (b) female mammals only

Explanation:
1. Mammary glands are found only in female mammals.
2. Their function is to nourish the young after birth.

Teacher's Note:
1. Mammals are named after mammary glands.