Identify the correct statements concerning the stages of spermatogenesis:
(I) Spermatogenesis begins at puberty due to a significant increase in hypothalamic GnRH. (II) Each diploid spermatogonium contains 46 chromosomes and multiplies by mitotic division. (III) Primary spermatocytes undergo meiotic reduction division to produce two unequal, haploid secondary spermatocytes. (IV) Secondary spermatocytes undergo the second meiotic division to produce four equal, haploid spermatids.
Explanation: Statements (I), (II), and (IV) are correct. Statement (III) is incorrect because the first meiotic division produces two equal haploid secondary spermatocytes.
Question 12 of 100
📘 CLASS XII
Consider the following terminologies of male gamete differentiation and release:
(I) The transformation of haploid spermatids into spermatozoa is known as spermiogenesis. (II) During spermiogenesis, the sperm heads remain free and do not interact with Sertoli cells. (III) The release of mature spermatozoa from the seminiferous tubules is called spermiation. (IV) Spermiation is directly stimulated by the hormone progesterone.
Explanation: Statements (I) and (III) are correct. Statement (II) is incorrect because sperm heads remain embedded in Sertoli cells during spermiogenesis. Statement (IV) is incorrect because spermiation is regulated mainly by FSH and androgens, not progesterone.
Question 13 of 100
📘 CLASS XII
Examine the hormonal regulation of the male reproductive system:
(I) GnRH is a hypothalamic hormone that acts on the anterior pituitary gland. (II) LH acts on Leydig cells and stimulates the synthesis and secretion of estrogens. (III) Androgens stimulate the process of spermatogenesis. (IV) FSH acts on Sertoli cells and stimulates the secretion of factors that help in spermiogenesis.
Explanation: Statements (I), (III), and (IV) are correct. Statement (II) is incorrect because LH stimulates Leydig cells to produce androgens, not estrogens.
Question 14 of 100
📘 CLASS XII
Read the statements regarding the structure of a mature human sperm:
(I) A plasma membrane envelops the entire body of the sperm. (II) The sperm head contains an elongated diploid nucleus. (III) The acrosome is a cap-like structure filled with enzymes that aid in fertilization. (IV) The middle piece contains numerous mitochondria that produce energy for tail movement.
Explanation: Statements (I), (III), and (IV) are correct. Statement (II) is incorrect because the sperm head contains an elongated haploid nucleus, not a diploid nucleus.
Question 15 of 100
📘 CLASS XII
Which of the following parameters are required for normal fertility in a human male ejaculate?
(I) A single coitus ejaculates about 200 to 300 million sperms. (II) At least 40% of the ejaculated sperms must have a normal shape and size. (III) At least 60% of the sperms must show vigorous motility. (IV) Secretions of epididymis, vas deferens, seminal vesicle, and prostate are essential for sperm maturation.
Explanation: Statements (I) and (IV) are correct. Statements (II) and (III) are incorrect because for normal fertility, at least 60% of sperms should have normal shape and size, and at least 40% should show vigorous motility.
Question 16 of 100
📘 CLASS XII
Analyze the statements below concerning the initiation of oogenesis:
(I) Oogenesis is initiated during the embryonic development stage of the female. (II) Millions of gamete mother cells (oogonia) are formed within each fetal ovary, and more oogonia are continuously formed after birth. (III) Oogonia enter prophase-I of meiotic division and get temporarily arrested at this stage as primary oocytes. (IV) Primary oocytes are diploid cells containing 46 chromosomes.
Explanation: Statements (I), (III), and (IV) are correct. Statement (II) is incorrect because no additional oogonia are formed after birth.
Question 17 of 100
📘 CLASS XII
Trace the development of ovarian follicles up to ovulation:
(I) At puberty, only 60,000–80,000 primary follicles are left in each ovary. (II) Secondary follicles are characterized by a fluid-filled cavity called the antrum. (III) The tertiary follicle has its theca layer organized into an inner theca interna and an outer theca externa. (IV) The secondary oocyte forms a new membrane called the zona pellucida.
Explanation: Statements (I), (III), and (IV) are correct. Statement (II) is incorrect because the fluid-filled cavity (antrum) appears in the tertiary follicle, not the secondary follicle.
Question 18 of 100
📘 CLASS XII
Regarding the first meiotic division during oogenesis, choose the correct statements:
(I) The first meiotic division is completed within the secondary follicle stage. (II) It is an equal division resulting in two secondary oocytes of the same size. (III) It produces a large haploid secondary oocyte and a tiny first polar body. (IV) The secondary oocyte retains the bulk of the nutrient-rich cytoplasm of the primary oocyte.
Explanation: Statements (III) and (IV) are correct. Statement (I) is incorrect because the first meiotic division is completed in the tertiary follicle. Statement (II) is incorrect because the division is unequal, producing a large secondary oocyte and a small first polar body.
Question 19 of 100
📘 CLASS XII
Analyze the statements regarding the human menstrual cycle:
(I) The first menstruation begins at puberty and is called menopause. (II) The cycle starts with the menstrual phase, which typically lasts for 3 to 5 days. (III) Menstrual flow results from the breakdown of the endometrial lining of the uterus and its blood vessels. (IV) During the follicular phase, the primary follicles grow and the endometrium regenerates through proliferation.
Explanation: Statements (II), (III), and (IV) are correct. Statement (I) is incorrect because the first menstruation is called menarche, whereas menopause is the permanent cessation of menstruation around the age of 50 years.
Question 20 of 100
📘 CLASS XII
Select the correct statements regarding the hormonal fluctuations during the menstrual cycle:
(I) Secretion of LH and FSH increases gradually during the follicular phase. (II) LH and FSH attain peak levels in the middle of the cycle (around the 14th day). (III) A rapid secretion of LH leading to its maximum level is called the LH surge. (IV) The LH surge induces the rupture of the secondary follicle to release the primary oocyte.
Explanation: Statements (I), (II), and (III) are correct. Statement (IV) is incorrect because the LH surge induces rupture of the Graafian follicle and releases the secondary oocyte, not the primary oocyte.
