Question 22N.1A.HL.TZ0.40
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1A.HL.TZ0.40 |
| Level | HL | Paper | 1A | Time zone | TZ0 |
| Command term | Question number | 40 | Adapted from | N/A |
What is the role of HCG in pregnancy?
A. It is secreted by the embryo to stimulate progesterone secretion by the ovary during early pregnancy.
B. Together with oxytocin, it is involved in the positive feedback required for uterine contractions during birth.
C. It sustains the secretion of progesterone by the placenta throughout pregnancy.
D. It stimulates the ovary to maintain secretion of estrogen in early pregnancy.
[1]
A
This question was answered correctly by less than half of candidates and the discrimination index was relatively low. The expected answer was A because embryos do secrete HCG, and because HCG does stimulate progesterone secretion by the ovary. The answer is a direct restatement of one of the understandings in sub-topic 11.4 of the program. Some of the better-prepared candidates must have rejected this answer and chosen another instead. Answers B and C were undoubtedly incorrect. Answer D stated that HCG stimulates the ovary to maintain secretion of estrogen during early pregnancy. Estrogen levels are low during the months when HCG from the embryo is sustaining pregnancy and they are lower than progesterone levels until about week 24 of a pregnancy, when the placenta has become responsible for HCG secretion. Answer A was therefore a better answer than D, though in retrospect a more obviously incorrect distractor should have been used for D.
