MCAT Behavioral Sciences Question 233: Answer and Explanation

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Question: 233

3. A researcher removes the adrenal glands from a rat and then supplements the rat with baseline levels of steroids for the remainder of its lifespan. Which of the following would be expected?

I. Blunted sympathetic nervous system response

II. Slowing of age-related neurodegeneration

III. Enhancement of LTP

  • A. II only
  • B. II and III
  • C. I and II
  • D. I, II and III

Correct Answer: C

Explanation:

Item I is true: The adrenal glands secrete both steroid hormones (from the adrenal cortex) and epinephrine (from the adrenal medulla). If the researcher only replaces the steroids, then the sympathetic response (which relies on epinephrine) could be blunted (choices A and B can be eliminated). Since both remaining answer choices include Item II, then Item II must be true and we only need to evaluate Item III. Item III is false: Based on Figure 1, corticosteroids do not seem to play an integral role in LTP. In addition, the passage only discusses their possible involvement in neuronal cell death at high concentrations. Keeping baseline levels may not lead to cell death, but would not necessarily enhance LTP (choice D can be eliminated and choice C is correct). Note that Item II is in fact true: Based on information in the passage (the Glucocorticoid Aging Hypothesis), stress levels of corticosteroids could lead to age-related neurodegeneration. Thus, if the levels of these hormones are kept at baseline throughout the life of the animal, it is possible to attenuate age-related neurodegeneration.

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