Question 126·Hard·Inferences
Biologist Karen Tse investigated whether roosting temperature influences parasite load in two species of cave-dwelling bats. She compared colonies that selected warm roof crevices (about 32 °C) with those that roosted in cooler limestone fissures (around 18 °C). Although previous studies show that the bats’ immune systems work more efficiently at higher body temperatures, Tse found that colonies in the cooler sites harbored significantly fewer mites. She proposes two non-exclusive explanations: mites reproduce more readily in heat, and the warm-roosting bats expend extra energy on cooling behaviors, leaving less time for grooming.
These findings most strongly suggest that, for these bat species, ______
Which choice most logically completes the text?
For inference-based sentence completions, restate the key result in your own words, especially any mismatch between what you’d expect and what the study found. Then pick the choice that captures that takeaway with careful, evidence-based wording. Eliminate choices that (1) contradict the stated result, (2) introduce a new causal factor the passage doesn’t discuss, or (3) overcommit to one explanation when the passage indicates multiple possibilities.
Hints
Focus on the key result
Pay attention to the surprising outcome: which roost temperature is associated with fewer mites?
Use the contrast to form an inference
The passage says immune efficiency is better at higher temperatures, but the mite result goes the other way. What does that imply about what matters most for mite load?
Use the proposed explanations as support
The author gives two reasons warm roosts might still have more mites. Use those reasons to decide which conclusion is best supported.
Avoid choices that overcommit to one cause
Be cautious with answers that claim one factor is the primary or only cause when the passage explicitly offers two non-exclusive explanations.
Step-by-step Explanation
Clarify what the question is asking
The question asks what the findings "most strongly suggest" about these bat species. You need a conclusion that follows from the study’s result and the researcher’s proposed explanations, without adding new claims.
Identify the key contrast in the passage
The passage presents a contrast:
- Prior research: bats’ immune systems work more efficiently at higher body temperatures.
- Tse’s finding: colonies in cooler roosts have significantly fewer mites than colonies in warm roosts.
So the expected benefit of warmth (better immune efficiency) does not correspond to fewer mites in this study.
Connect the result to Tse’s proposed explanations
Tse proposes two non-exclusive explanations for why warm roosts have more mites:
- Mites reproduce more readily in heat.
- Warm-roosting bats spend energy on cooling behaviors, leaving less time for grooming.
Both explanations point to roost temperature (directly or indirectly) increasing mite load despite the immune advantage of higher temperatures.
Choose the option that matches the supported inference
The best-supported inference is that roost temperature’s overall impact on mite infestation can outweigh the temperature-related immune benefit.
Therefore, the correct completion is: "roost temperature can exert a stronger influence on mite infestation levels than temperature-dependent immune efficiency."