PSAT Reading Question 507: Answer and Explanation

Question: 507

According to the passage as a whole, the overall role of Methanosphaera stadtmanae with respect to human health is

• A. uniformly positive.
• B. primarily beneficial.
• C. somewhat harmful.
• D. mostly parasitic.

Correct Answer: B

Explanation:

(B) The author states that Methanosphaera stadtmanae is helpful to humans because it conserves energy and aids in digestion (lines 44–50). He also says that it likely contributes to IBD in some individuals. Therefore, M. stadtmanae plays an important and helpful role in the body. However, if homeostasis is not maintained, it can also have negative effects in the body. Therefore, it is primarily beneficial, choice (B). It isn't uniformly positive, choice (A), because of its role in IBD. It isn't somewhat harmful, as in choice (D), because the author explicitly states in the first paragraph that M. stadtmanae is beneficial to humans. It's necessary for energy conservation and digestion.