NEET Biology Human Reproduction MCQs Set 23

Answer: (c) Testis

Explanation:
1. Primary sex organs (gonads) produce gametes and sex hormones.
2. In a male, the testis is the gonad; the others are accessory organs.

Teacher's Note:
1. Gonads = testes in males, ovaries in females.
2. Everything else in the reproductive tract is an accessory organ.

Answer: (d) Vas deferens

Explanation:
1. Accessory sex organs are ducts and glands that help in the transport and nourishment of gametes.
2. The vas deferens is an accessory duct; the beard is a secondary sexual character, not an organ.

Teacher's Note:
1. Distinguish sex organs from sexual characters.
2. Ducts, glands and external genitalia are accessory organs.

Answer: (a) Citric acid

Explanation:
1. Seminal plasma contains fructose, calcium, citric acid and some enzymes and prostaglandins.
2. Citric acid is the acid reported in semen.

Teacher's Note:
1. Seminal vesicles supply fructose for sperm energy.
2. Remember: fructose, citrate, prostaglandins.

Answer: (c) To provide a medium for the movement of sperms

Explanation:
1. Seminal plasma is alkaline and nutrient rich.
2. It acts as a transport medium and provides energy to sperm.

Teacher's Note:
1. It neutralises the acidity of the vagina.
2. It contains fructose as the energy source.

Answer: (a) Testes with epididymis

Explanation:
1. Rete testis opens into 10-12 vasa efferentia.
2. These tubules carry sperm into the epididymis.

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

Answer: (c) Cryptorchidism

Explanation:
1. Testes normally descend from the abdomen to the scrotum before birth.
2. Failure of descent is cryptorchidism and it prevents spermatogenesis because the abdomen is too warm.

Teacher's Note:
1. Spermatogenesis needs a temperature lower than body temperature.
2. Castration means removal of the testes.

Answer: (b) Inguinal canal

Explanation:
1. The testes descend from the abdomen through the inguinal canal.
2. The canal remains as the link between scrotal sac and abdominal cavity.

Teacher's Note:
1. Weakness of the canal wall can cause an inguinal hernia.
2. The spermatic cord passes through this canal.

Answer: (b) Testis

Explanation:
1. Each testis is covered by a dense fibrous capsule, the tunica albuginea.
2. It sends septa inwards and divides the testis into lobules.

Teacher's Note:
1. Each lobule holds 1-3 seminiferous tubules.
2. The ovary has a similar capsule, also called the tunica albuginea.

Answer: (c) Seminiferous tubules

Explanation:
1. Sperm are produced in the seminiferous tubules.
2. Uriniferous tubules are renal and Malpighian tubules are insect excretory organs.

Teacher's Note:
1. About 250 testicular lobules in each testis.
2. Leydig cells lie between the tubules.

Answer: (d) Germinal epithelium

Explanation:
1. The wall of the tubule has germinal epithelium that includes spermatogonial cells.
2. It also contains Sertoli cells.

Teacher's Note:
1. Germinal epithelium = cells that divide to form gametes.
2. Sertoli cells are the supporting cells.

Answer: (c) Extra-abdominal cavity (scrotum)

Explanation:
1. Testes hang outside the abdomen in the scrotum.
2. This keeps them 2-3 degrees Celsius cooler than the body core, which is needed for sperm production.

Teacher's Note:
1. The cremaster muscle adjusts the testes' position with temperature.
2. The scrotum is the thermoregulator of the testes.

Answer: (a) Testis of mammals

Explanation:
1. Sustentacular cells are the Sertoli cells in the seminiferous tubules.
2. They nourish the developing sperm.

Teacher's Note:
1. Sertoli cells also secrete inhibin and androgen-binding protein.
2. Spermatids stay attached to Sertoli cells until spermiation.

Answer: (b) Prepuce

Explanation:
1. The enlarged tip of the penis is covered by a loose fold of skin called the prepuce (foreskin).
2. Removal of the prepuce is circumcision.

Teacher's Note:
1. The prepuce is also called foreskin.
2. Clitoris has a similar covering, the hood.

Answer: (a) Inguinal canal

Explanation:
1. The inguinal canal links scrotal sac and abdominal cavity.
2. Haversian canals occur in bone.

Teacher's Note:
1. Testes descend through it during development.
2. It is a possible site of hernia.

Answer: (d) Requirement of low temperature for spermatogenesis

Explanation:
1. Sperm formation needs a temperature slightly below body temperature.
2. The scrotum provides this cooler environment.

Teacher's Note:
1. Abdominal testes (cryptorchidism) are sterile.
2. Birds are exceptions with internal testes.

Answer: (c) Testis

Explanation:
1. Leydig (interstitial) cells lie between the seminiferous tubules.
2. They secrete testosterone.

Teacher's Note:
1. LH stimulates Leydig cells.
2. FSH acts on Sertoli cells.

Answer: (c) Cowper's gland

Explanation:
1. Cowper's (bulbourethral) gland is male specific.
2. Bartholin's glands occur in the female.

Teacher's Note:
1. Female counterpart of Cowper's gland: Bartholin's gland.
2. Male accessory glands: seminal vesicles, prostate, bulbourethral glands.

Answer: (d) Testis

Explanation:
1. They are the sperm-forming tubules of the testis.

Teacher's Note:
1. Do not confuse with uriniferous tubules of the kidney.
2. About 800 tubules per testis.

Answer: (d) Sperm gradually disappear from semen

Explanation:
1. Vasectomy blocks the vas deferens but sperm already in the tract remain for some time.
2. So sperm disappear from semen gradually; seminal fluid is still produced.

Teacher's Note:
1. Contraceptive effect is not immediate after the operation.
2. Testosterone production is not affected.

Answer: (c) 3 degrees Celsius

Explanation:
1. The scrotum is 2-3 degrees Celsius cooler than the abdominal cavity.
2. Of the options, 3 degrees Celsius is correct.

Teacher's Note:
1. Sperm production is temperature sensitive.
2. The cremaster muscles raise or lower the testes.

Answer: (a) Male mammals

Explanation:
1. Cowper's glands are the bulbourethral glands of male mammals.

Teacher's Note:
1. They are paired.
2. Their pre-ejaculatory secretion lubricates the urethra.

Answer: (a) Tunica propria

Explanation:
1. Each seminiferous tubule is surrounded by a thin fibrous layer, the tunica propria.
2. Tunica albuginea covers the whole testis.

Teacher's Note:
1. Tunica propria surrounds tubules; tunica albuginea surrounds the whole organ.
2. This is a common NEET confusion.

Answer: (c) Male accessory glands

Explanation:
1. Seminal plasma from the male accessory glands contains fructose, calcium and enzymes.
2. It forms the bulk of semen.

Teacher's Note:
1. Seminal plasma = fluid portion of semen.
2. Sperm form only a small part of semen volume.

Answer: (c) Prostate gland

Explanation:
1. The prostate is a single, chestnut-sized gland below the bladder.
2. Seminal vesicles and Cowper's glands are paired.

Teacher's Note:
1. Prostate secretion is alkaline and milky.
2. Bartholin's glands are female.

Answer: (c) Removal of the movable skin (prepuce) of the glans penis

Explanation:
1. The prepuce is a retractable fold of skin covering the glans.
2. Circumcision removes it.

Teacher's Note:
1. The glans itself remains intact.
2. The foreskin can retain secretions (smegma).