In the spring and fall eastern pipistrelle bats roost deep inside cave

Question

In the spring and fall, eastern pipistrelle bats roost deep inside caves. They feed at night on flying insects and must leave the cave to catch their prey. Flying insects are much more abundant on warm nights than on cool ones. Researchers found that many more bats leave the caves on warm nights than on cool nights, even though the temperature within the caves where the bats roost remains virtually the same from one night to the next.

Which one of the following, if true, most helps to explain the researchers' findings?

(A) The researchers studied only female bats, which tended to catch more insects on warm nights than did the male bats.

(B) Eastern pipistrelle bats can detect changes in barometric pressure within the caves that correlate closely with changes in temperature outside the caves.

(C) Eastern pipistrelle bats are incapable of long periods of sustained activity outside the roosting caves on very cool spring and fall evenings.

(D) Because of the long period of winter inactivity, eastern pipistrelle bats tend to consume more insects per day in the spring and fall than in the summer.

(E) During the periods in which the researchers studied the bats, on most evenings over half of the bats left the caves in search of food.

ankushsambare · Answer

Premise
Bats roost inside caves where the temperature stays almost the same every night.
Flying insects are more abundant on warm nights.
Researchers found that more bats leave the caves on warm nights than on cool nights.
Question
How do bats know whether the outside night is warm or cool if cave temperature stays constant?
Prethinking
We need an explanation showing that bats can somehow sense outside weather conditions while still inside the cave.
Option check
A Only female bats studied → does not explain how bats know outside temperature
B Bats detect barometric pressure changes linked to outside temperature → explains how they know when warm nights occur
C Bats cannot stay active on cool nights → explains behavior partly, but not how they know before leaving
D Spring/fall eating habits → irrelevant
E Most bats left on many evenings → irrelevant
 Correct Answer B 
 Conclusion
B best explains the findings because it shows bats can detect pressure changes inside the cave that signal warmer temperatures outside, helping them decide when to leave and hunt.

guddo · Answer

In the spring and fall, eastern pipistrelle bats roost deep inside caves. They feed at night on flying insects and must leave the cave to catch their prey. Flying insects are much more abundant on warm nights than on cool ones. Researchers found that many more bats leave the caves on warm nights than on cool nights, even though the temperature within the caves where the bats roost remains virtually the same from one night to the next. 
 
Which one of the following, if true, most helps to explain the researchers' findings?

The puzzle is that bats leave more often on warm nights, even though the cave temperature stays almost the same. So the answer should explain how bats inside the cave can respond to outside conditions.  The key issue is how the bats detect that it is warm outside .

(A) The researchers studied only female bats, which tended to catch more insects on warm nights than did the male bats.

Wrong. This does not explain how the bats know whether the outside night is warm or cool.

(B) Eastern pipistrelle bats can detect changes in barometric pressure within the caves that correlate closely with changes in temperature outside the caves.

Correct. If bats can detect pressure changes inside the cave that correspond to outside temperature, then they can tell when warm nights are likely. That explains why more bats leave on warm nights, when  more insects are available .

(C) Eastern pipistrelle bats are incapable of long periods of sustained activity outside the roosting caves on very cool spring and fall evenings.

Tempting, but incomplete. This explains why cool nights are bad for activity, but it does not explain how bats inside a cave with stable temperature know whether the outside is cool.

(D) Because of the long period of winter inactivity, eastern pipistrelle bats tend to consume more insects per day in the spring and fall than in the summer.

Wrong. This compares seasons, not warm nights versus cool nights within spring and fall.

(E) During the periods in which the researchers studied the bats, on most evenings over half of the bats left the caves in search of food.

Wrong. This does not explain why more bats left on warm nights than on cool nights.

Answer: (B)

yc168 · Answer

OE for reference:

Overview:  
Eastern pipistrelle bats often leave their caves at night to hunt for flying insects. Researchers studying these bats found that the temperature inside the bats' caves remains constant, but that more bats leave the caves on warm nights—when insects are more abundant—than on cool nights. These findings are interesting: if the bats' caves don't vary in temperature, what causes the bats' behavior to change on warm nights as opposed to cool nights? You are asked to select the answer choice that most helps to explain these findings.

The Correct Answer:

B  If (B) is true, it identifies a factor—changes in barometric pressure—that the bats can detect, and that is closely associated with temperature changes. This helps to account for why the bats' behavior varies with temperature: while the bats cannot detect temperature changes directly, they can detect and respond to something that closely correlates with these changes. By identifying a mechanism that allows the bats to respond to changes in the temperature outside their caves, (B) goes a long way toward explaining the researchers' findings.

The Incorrect Answer Choices:

A  Even if the researchers studied only female bats, the finding that more female bats leave the caves on warm nights would still stand in need of explanation. Thus, (A) does not help us to account for the researchers' findings.

C  (C)'s claim that the bats cannot engage in sustained activity on very cool evenings gives us a reason why bats might not want to leave their caves on very cool evenings, but it doesn't help at all to explain why they are less likely to leave their caves on evenings that are merely cool. Moreover, (C) tells us nothing about why the bats' behavior varies with temperature even though temperature changes cannot be detected from within the bats' caves.

D  If the bats consume more insects during the spring and fall than during the summer, then they might leave their caves more often during the spring and fall than during the summer. If anything, this would make the researchers' findings harder to explain, since it would suggest that more bats leave the caves during relatively cool seasons, but also during relatively warm nights.

E  The statement that over half of the bats leave the caves on most nights does not change the researchers' observation that more bats leave on warm nights than on cool nights, nor does it explain why this is the case. Consequently, that statement does not help us to account for the researchers' findings.

In the spring and fall eastern pipistrelle bats roost deep inside cave

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In the spring and fall eastern pipistrelle bats roost deep inside cave

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

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