Human reproduction — NEET Biology Questions 2026

Pregnancy halts the menstrual cycle due to hormonal changes.

Alveolar cells in the mammary gland synthesize milk and store it in their lumens.

The vas deferens ascends and loops to ensure sperm movement toward the ejaculatory duct.

NCERT states “In adults, each testis is oval in shape, with a length of about 4 to 5 cm and a width of about 2 to 3 cm.” The Assertion is false because it removes the qualifier “about” - NCERT provides approximate ranges acknowledging natural variation. The Reason is also false - there is no standardization of testicular size, and NCERT’s use of “about” indicates individual variation exists.

Let's arrange the events in chronological order based on the NCERT description of the menstrual cycle: 1. Follicular growth and estrogen production (A) characterize the follicular phase, where primary follicles mature and secrete estrogens. 2. Rapid secretion of LH (LH surge) (B) occurs around mid-cycle, following the follicular phase, and is crucial for ovulation. 3. Release of ovum from Graafian follicle (C) is directly induced by the LH surge, marking ovulation. 4. Formation of corpus luteum (D) occurs after ovulation, from the remaining parts of the Graafian follicle. 5. Secretion of large amounts of progesterone for endometrial maintenance (E) is the primary function of the corpus luteum during the luteal phase. 6. Breakdown of endometrial lining and its blood vessels (F) occurs if fertilization does not happen, due to the degeneration of the corpus luteum and subsequent drop in progesterone, leading to menstruation. Thus, the correct sequence is A → B → C → D → E → F.