NEET Biology Human Reproduction MCQs Set 24

Answer: (b) In stimulating sperm activity

Explanation:
1. Prostate secretion is slightly alkaline.
2. It activates sperm motility and neutralises vaginal acidity.

Teacher's Note:
1. Prostatic fluid is rich in citrate and zinc.
2. Seminal vesicles provide fructose.

Answer: (a) Spermatogenesis

Explanation:
1. Spermatogenesis needs a temperature below that of the abdomen.
2. Hence the testes descend into the scrotum.

Teacher's Note:
1. Descent happens in the last months of fetal life.
2. Failure leads to sterility.

Answer: (a) Sertoli cells

Explanation:
1. Sertoli (sustentacular) cells nourish developing spermatids.
2. Interstitial (Leydig) cells secrete testosterone.

Teacher's Note:
1. Spermatids remain embedded in Sertoli cells.
2. These cells form the blood-testis barrier.

Answer: (b) Mesodermal in origin

Explanation:
1. Gonads develop from intermediate mesoderm.
2. So the gametes arise through mesodermal gonads.

Teacher's Note:
1. Primordial germ cells migrate to the gonad.
2. Kidney and gonads share a mesodermal origin.

Answer: (a) Breast

Explanation:
1. Breast development is a secondary sexual character in females.
2. Ovary and testis are primary sex organs.

Teacher's Note:
1. Secondary sexual characters appear at puberty under sex hormones.
2. They are not directly involved in reproduction.

Answer: (d) Coelom

Explanation:
1. At ovulation the secondary oocyte bursts out into the body cavity (coelom).
2. The fimbriae of the oviduct then catch it.

Teacher's Note:
1. The ostium of the oviduct lies near the ovary.
2. Ovulation is controlled by the LH surge.

Answer: (b) Cervix

Explanation:
1. The cervix is the narrow lower end that opens into the vagina.
2. The cervical canal with the vagina forms the birth canal.

Teacher's Note:
1. Cervical cancer is detected by a Pap smear.
2. The cervix is a muscular, gland-rich region.

Answer: (c) Both testes and ovary

Explanation:
1. The seminiferous tubules and the ovarian surface have germinal epithelium.

Teacher's Note:
1. Both gonads form gametes from germinal epithelium.
2. The ovarian surface layer is cuboidal.

Answer: (b) 11-14 years

Explanation:
1. Puberty begins around 11-14 years in girls.

Teacher's Note:
1. Menarche occurs during puberty.
2. It is triggered by GnRH from the hypothalamus.

Answer: (a) Ovary

Explanation:
1. Mesovarium attaches the ovary to the broad ligament of the uterus.

Teacher's Note:
1. Mesorchium is the male equivalent.
2. It carries blood vessels to the ovary.

Answer: (b) Atresia

Explanation:
1. Many follicles never ovulate and degenerate; this is atresia.

Teacher's Note:
1. Only about 400 oocytes ovulate in a lifetime.
2. At birth there are about 2 million follicles.

Answer: (c) Uterus

Explanation:
1. The endometrium is the innermost glandular layer of the uterus.

Teacher's Note:
1. It undergoes cyclical changes in the menstrual cycle.
2. The embryo implants in the endometrium.

Answer: (d) Labia minora

Explanation:
1. Two labia minora meet at the top and enclose the clitoris.

Teacher's Note:
1. Mons pubis is the fatty pad above.
2. Labia majora are the outer folds.

Answer: (d) Epididymis

Explanation:
1. The vulva includes the mons pubis, labia, clitoris and vestibule.
2. The epididymis is a male structure.

Teacher's Note:
1. Vulva = external genitalia of the female.
2. Epididymis stores sperm.

Answer: (d) Sertoli cells

Explanation:
1. Spermatids remain attached to Sertoli cells until spermiation.

Teacher's Note:
1. Kupffer cells are in the liver.
2. Sertoli cells provide nutrition.

Answer: (c) First maturation division

Explanation:
1. Meiosis I is the reduction division; the chromosome number halves.
2. Meiosis II is equational.

Teacher's Note:
1. Primary spermatocyte (2n) gives two secondary spermatocytes (n).
2. Meiosis II separates chromatids.

Answer: (b) Equational division

Explanation:
1. The second meiotic division separates sister chromatids with no change in the chromosome number.

Teacher's Note:
1. Meiosis I is reductional.
2. Meiosis II resembles mitosis.

Answer: (c) 4

Explanation:
1. A primary spermatocyte divides by meiosis I into 2 secondary spermatocytes.
2. Each divides again to give 2 spermatids: total 4 sperm.

Teacher's Note:
1. Oogenesis gives only one ovum per primary oocyte.
2. Sperm number is multiplied at the spermatogonial stage.

Answer: (a) Leeuwenhoek

Explanation:
1. Antonie van Leeuwenhoek first observed human sperm using a microscope.

Teacher's Note:
1. Graaf described the mammalian follicle.
2. Leeuwenhoek lived in the 17th century.

Answer: (d) Tail

Explanation:
1. The distal centriole gives rise to the axial filament of the tail.
2. The head contains the nucleus and acrosome.

Teacher's Note:
1. The proximal centriole helps in cleavage of the zygote.
2. Mitochondria are in the middle piece.

Answer: (a) Complete sperm

Explanation:
1. In humans (as in most mammals) the whole sperm enters the ooplasm.

Teacher's Note:
1. In some animals only the head enters.
2. The tail degenerates afterwards.

Answer: (b) Perforatorium

Explanation:
1. The perforatorium lies between acrosome and nucleus.

Teacher's Note:
1. Nebenkern is the mitochondrial sheath.
2. Perivitelline space is in the egg.

Answer: (c) Present in very little amount

Explanation:
1. The head is mostly nucleus with a very thin cytoplasmic layer.

Teacher's Note:
1. Excess cytoplasm is shed during spermiogenesis.
2. This makes the sperm light and motile.

Answer: (c) Penetration of sperm into the ovum

Explanation:
1. The acrosome releases enzymes (hyaluronidase, acrosin) that dissolve egg coverings.

Teacher's Note:
1. Fusion of nuclei is karyogamy.
2. Motility needs the tail.

Answer: (a) Elongated nucleus and acrosomal material

Explanation:
1. The head contains a haploid nucleus and an acrosome cap.

Teacher's Note:
1. Centrioles are in the neck.
2. Mitochondria are in the middle piece.