Challenging Biology Question Example - Ovarian Cycle
One of the toughest things about the MCAT is that it requires you not only to have a good understanding of the topics that it covers, but also to be able to combine them and apply them to novel scenarios. The following problem is an example of an MCAT question that asks you to do just that. However, by simplifying in a step-by-step way, it becomes easier to narrow in on the correct answer!
Menopause is characterized by ovarian failure, meaning that follicles no longer respond to gonadotropin stimulation. Which of the following would be the expected result of a Western blot analysis on a blood sample of a post-menopausal woman (as compared to pre-menopausal)?
The first step to solving this question is to determine what menopause actually entails. The MCAT doesn’t expect you to know this kind of thing – the question is actually telling you, which is something a lot of people don’t realize! So, once we see that menopause means follicles don’t respond to gonadotropins, we can go on to determine what this actually means for the various hormone levels.
Gonadtropins are the tropic hormones that stimulate the gonads, and include FSH (follicle stimulating hormones) and LH (luteinizing hormone). Normally, in a woman, they stimulate the ovarian follicles to produce estrogen, which then feed back and inhibit the release of the gonadotropins from the anterior pituitary. However, if the follicles can no longer respond, estrogen will NOT be produced. That means estrogen will NOT feed back and inhibit release of the gonadotropins, so their levels will be higher than usual. With this, we can eliminate the answer choices “elevated estrogen” (since estrogen will be low, not high) and “reduced FSH and LH” (since FSH and LH will be high, not low).
Now, this is the point at which a lot of people would get stuck. How do we decide between the two remaining answer choices, which both seem correct? This is where noticing the experimental technique mentioned in the question becomes critical. The question specifies that these hormones are being measured with a Western blot, which is a method that detects protein. FSH and LH are peptide hormones, so are made of protein, whereas estrogen is a steroid hormone, and is considered a lipid. That means that only FSH and LH levels can be detected with a Western blot, NOT estrogen levels. So even though “reduced estrogen” is technically accurate, it would not be detected by the method listed in the question, and is therefore not correct. Instead, “elevated FSH and LH” is our correct answer.
This question is a great example of how the MCAT expects you to be able to combine concepts from seemingly unrelated topics (for example, here we’re combining the physiology of the ovarian cycle with a biochemistry technique) and apply them. Any questions? Comment 🙂
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