Question

UNIT 8-2 The female reproductive hormone cycle An endocrinologist has been studying an enzyme that she suspects is the rate-limiting step in the conversion of cholesterol to estrogen. It is reported in the literature that female mice with a mu the gene coding for this enzyme reach sexual maturity earlier than wild type mice. She measures plasma estrogen levels in mutant and wild type mice at 3 weeks of age, prior to sexual maturity which typically occurs by 6 weeks of age. tation in TrialWild type Mutant 2 8.1 4.5 The results, in estrogen pg/mL of plasma are given in the table: 7.6 5.5 What conclusion can be made based on this data? 12.5 10.7 8.6 8.2 A The presence of the wild type enzyme increases estrogen concentration. B. The presence of the wild type enzyme 8 6.3 increases cholesterol concentration. C. The presence of the mutant enzyme increases estrogen concentration. D. The presence of the mutant enzyme increases cholesterol concentration. Recent studies have shown that cholesterol levels in women can vary significantly depending on where a woman is in her reproductive cycle. Most notable is the fact that total and LDL cholesterol typically decline at the points in the cycle where estrogen levels are at their highest. Based on this we would expect that total and LDL cholesterol levels would be lowest A. following menopause B. during menstruation C. during ovulation D. prior to puberty Based on the data presented, it is likely that A. B. C. D. wild type mice reach sexual maturity faster than the mutant mice the mutant strain mice will not reach sexual maturity the mutant strain mice will have a lower cholesterol level than wild type mice wild type mice will not reach sexual maturity If plasma cholesterol levels were to be measured, what would you expect to see in female mice that have reached sexual maturity as compared to female mice that are far from reaching sexual maturity? A. B. C. D. Cholesterol levels would be increased in wild type mice that have reached sexual maturity as compared to wild type mice that have not reached sexual maturity. Cholesterol levels would be the same in wild type mice that have reached sexual maturity as compared to wild type mice that have not reached sexual maturity. Cholesterol levels would be increased in mutant mice that have reached sexual maturity as compared to mutant mice that have not reached sexual maturity Cholesterol levels would be decreased in mutant mice that have reached sexual maturity as compared to mutant mice that have not reached sexual maturity

I got C for the first three and a little confused on the fourth one, could anyone tell me if I'm correct on 1-3 and what the answer and reasoning of #4?

Answer 1

For question 4, the answer is

D. cholesterol levels would be decreased in mutant mice that have reached sexual maturity as compared to mutant mice that have not reached sexual maturity.

The reason is that in mutant mice which have reached sexual maturity, cholesterol is converted into estrogen, and so its levels decrease. However, those mice that have not reached sexual maturity does not convert cholesterol into estrogen, and the levels remain as such.

Answers for remaining questions are option (C).