IB DP Biology- D3.1 Reproduction- IB Style Questions For HL Paper 2 -FA 2025

What is a function of human chorionic gonadotropin (HCG)?

A. To stimulate the corpus luteum to produce progesterone during early pregnancy

B. To stimulate contraction of uterine muscles at the start of labour

C. To suppress progesterone release and prevent menstruation during pregnancy

D. To prevent polyspermy during fertilization in the oviduct

▶️ Answer/Explanation

Answer: A. To stimulate the corpus luteum to produce progesterone during early pregnancy

Explanation:

Human chorionic gonadotropin (HCG) is produced by the embryo shortly after fertilization and later by the placenta.
Its main function is to maintain the corpus luteum, ensuring continued progesterone production.
Progesterone preserves the uterine lining, prevents menstruation, and supports the early stages of pregnancy.

Why the other options are incorrect:

B: Uterine contractions at birth are triggered by oxytocin, not HCG.

C: HCG increases progesterone production rather than inhibiting it.

D: Polyspermy prevention occurs through rapid membrane changes in the egg, not through HCG.

Resources