Gametogenesis and Reproductive Cycles — NEET Biology

Correct answer: A — A–I–P, B–II–Q, C–III–R, D–IV–S

This question requires a three-way matching of hormones/substances, their sources, and their primary roles as described in the NCERT text. Evaluating each row: - **A. Oxytocin:** NCERT states, "This triggers release of oxytocin from the maternal pituitary. Oxytocin acts on the uterine muscle and causes stronger uterine contractions..." (Page 38, Section 2.7). Thus, Oxytocin (A) is from Maternal Pituitary (I) and Induces uterine contractions (P). So, A–I–P. - **B. Estrogens:** NCERT states, "Placenta also acts as an endocrine tissue and produces several hormones like... estrogens..." (Page 37, Section 2.6). The summary mentions, "The process of childbirth is called parturition which is induced by a complex neuroendocrine mechanism involving cortisol, estrogens and oxytocin." (Page 39, Summary). Thus, Estrogens (B) are from Placenta (II) and are Involved in induction of parturition (Q). So, B–II–Q. - **C. Relaxin:** NCERT states, "In the later phase of pregnancy, a hormone called relaxin is also secreted by the ovary. Let us remember that hCG, hPL and relaxin are produced in women only during pregnancy." (Page 37, Section 2.6). Thus, Relaxin (C) is from Ovary (III) and is Produced only during pregnancy (R). So, C–III–R. - **D. Colostrum:** NCERT states, "The milk produced during the initial few days of lactation is called colostrum which contains several antibodies absolutely essential to develop resistance for the new-born babies." (Page 38, Section 2.7). The source of milk (and thus colostrum) is mammary glands. Thus, Colostrum (D) is from Mammary Glands (IV) and Provides antibodies for newborn (S). So, D–IV–S. Therefore, the correct option is A–I–P, B–II–Q, C–III–R, D–IV–S. The tested concept is the understanding of hormones and substances, their respective origins, and their specific functions during pregnancy, parturition, and lactation.