Acacia trees are shrub-like, with some species having swollen thorns t

Question

Acacia trees are shrub-like, with some species having swollen thorns that serve as nests for three species of ants. A healthy tree can have hundreds of thorns, many containing one hundred ants each. Both the ants and the trees benefit. The ants get shelter and nectar from the base of the acacia leaves. And because the ants swarm to defend against birds or animals that interfere with the trees, the trees get protection from a major threat, browsing animals.

Researchers were puzzled to find that a grove of acacias fenced off from wild mammal herbivores looked sickly compared with their unfenced counterparts—the opposite of what might be expected, given that browsers had fed voraciously on the unfenced trees. The researchers had expected that without mammals to eat the fenced trees, the trees would shelter fewer and less aggressive ants—which turned out to be true—and that the trees would benefit from not having to use their resources to support the ants. But further investigation revealed that with reduced colonies, the ants became less well able to defend against a fourth species of ant. This ant species does not eat acacia nectar; it feeds away from the tree and does not defend it from attackers. Rather, it uses as its home the cavities created in the acacia trees by a wood-boring beetle.

1. According to the passage, which of the following is true?

A. The cavities sometimes created in certain species of acacia trees by wood-boring beetles benefit the trees.
B. Browsing animals that would usually feed off certain species of acacia trees do not do so if those trees are inhabited by certain species of ants.
C. At least one species of ant that can inhabit certain species of acacia tree does not feed on acacia nectar.
D. Certain species of acacia trees are inhabited by no more than three species of insects.
E. Certain species of acacia trees thrive best when entirely protected from browsing animals.

2. Information presented by the passage undermines which of the following claims?

A. Healthy acacia trees of the species in question may have hundreds of thorns.
B. With reduced colonies, the ants on the species of acacia trees in question become less able to defend their territory.
C. Acacia trees of the species in question are better off if there are fewer and less aggressive ants on the trees.
D. Acacia trees of the species in question, if protected from browsing animals, do not need to produce as much nectar.
E. Acacia trees of the species in question, if protected by fences, are less healthy than those not so protected.

3. The passage strongly suggests that the ants that typically live on healthy acacias of the species discussed in the passage

A. are less aggressive toward invasive insects than are the wood-boring beetles that sometimes inhabit acacias
B. deter animals from eating acacia foliage but do not harm them
C. are incapable of adapting to any other sort of habitat except acacia trees
D. migrate to unfenced acacias if those in which they live are fenced
E. do not respond defensively solely to browsing mammals and birds

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Show Answer Question #1

Official Answer

C

Show Answer Question #2

Official Answer

C

Show Answer Question #3

Official Answer

E

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Bunuel · Answer

Usually, there are 3 or 4 questions with the RC passage. Do you have screenshots of the missing ones? Could you please post them? Thank you!

purplelemonsoda · Answer

https://gmatclub.com/forum/download/file.php?id=83167 GMAT-Club-Forum-ly52mi6m.png

Bunuel · Answer

Added that question. Thank you!

purplelemonsoda · Answer

1.  Which of the following is true? 
 
  A. The cavities sometimes created in certain species of acacia trees by wood-boring beetles benefit the trees. 
 
  Why it’s wrong:  The passage says that these cavities are used by a fourth species of ant (which doesn't help defend the tree), not that they benefit the tree. There’s no mention of the cavities benefiting the tree itself, only that they provide a home for the ants.  
 
  B. Browsing animals that would usually feed off certain species of acacia trees do not do so if those trees are inhabited by certain species of ants. 
 
  Why it’s wrong:  This is the opposite of what the passage describes. The passage indicates that browsing animals are deterred by the ants' defense, but it doesn’t suggest that the presence of ants  completely stops  browsing animals from feeding on the acacia trees.  
 
  D. Certain species of acacia trees are inhabited by no more than three species of insects. 
 
  Why it’s wrong:  The passage discusses three species of ants, but there is also a fourth species of ant (not the ants that defend the tree) that inhabits the trees, as well as wood-boring beetles. So, there are more than three species of insects involved.  
 
  E. Certain species of acacia trees thrive best when entirely protected from browsing animals. 
 
  Why it’s wrong:  The passage contradicts this idea. When the acacia trees are fenced off and protected from browsing animals, the trees become sickly due to fewer aggressive ants defending them. So, they don’t thrive when entirely protected.  
  
2.  Information presented by the passage undermines which of the following claims? 
 
  A. Healthy acacia trees of the species in question may have hundreds of thorns. 
 
  Why it’s wrong:  The passage confirms that healthy acacia trees may have hundreds of thorns, which is a known characteristic of these trees. It doesn’t undermine this claim.  
 
  B. With reduced colonies, the ants on the species of acacia trees in question become less able to defend their territory. 
 
  Why it’s right:  The passage supports this claim. When the colonies of ants were reduced (due to the fencing off of the acacias from browsing animals), the ants were less aggressive and thus less able to defend the trees.  
 
  D. Acacia trees of the species in question, if protected from browsing animals, do not need to produce as much nectar. 
 
  Why it’s wrong:  The passage doesn’t directly address the amount of nectar produced by the trees, so this claim isn’t undermined by the information provided. The focus is more on the defense relationship between the ants and the trees.  
 
  E. Acacia trees of the species in question, if protected by fences, are less healthy than those not so protected. 
 
  Why it’s wrong:  The passage states that fenced-off acacia trees become sickly compared to the unfenced ones, so this claim is indeed supported, not undermined.  
  
3.  The passage strongly suggests that the ants that typically live on healthy acacias of the species discussed in the passage: 
 
  A. are less aggressive toward invasive insects than are the wood-boring beetles that sometimes inhabit acacias 
 
  Why it’s wrong:  The passage doesn’t make a direct comparison of the ants' aggressiveness toward invasive insects compared to wood-boring beetles. It focuses on the ants’ role in defending the tree, not their interaction with other species like the beetles.  
 
  B. deter animals from eating acacia foliage but do not harm them 
 
  Why it’s wrong:  The passage describes how the ants defend the trees aggressively from browsing animals, but it doesn’t say that the ants "do not harm" the animals. In fact, they swarm to defend the tree, indicating a stronger, more defensive action.  
 
  C. are incapable of adapting to any other sort of habitat except acacia trees 
 
  Why it’s wrong:  The passage doesn’t suggest that the ants are strictly confined to acacia trees. It talks about how the ants’ presence depends on the trees' condition, but there’s no claim that they are incapable of adapting elsewhere.  
 
  D. migrate to unfenced acacias if those in which they live are fenced 
 
  Why it’s wrong:  The passage doesn’t mention ants migrating between acacia trees, fenced or unfenced. It states that the reduced number of ants in the fenced trees makes them less aggressive, not that ants move between trees.  
 
  E. do not respond defensively solely to browsing mammals and birds 
 
  Why it’s right:  The passage implies that the ants defend the trees not just from browsing mammals and birds but also from other threats, such as the invasion of a fourth species of ant. Therefore, they don’t respond  only  to browsing mammals and birds.

kartickdey · Answer

Bunuel  Regarding Q1, it is appearing that the option C is more appealing than option B but still I could not find any proper reason to eliminate option B. Please clarify why option B is wrong.

guddo · Answer

1. According to the passage, which of the following is true? 
 
Some acacias house ants in swollen thorns. The ants get shelter and nectar, and in return they defend the tree from browsing animals. When researchers fenced out mammal herbivores, the trees looked worse because ant colonies became smaller and less aggressive, which made it easier for a fourth ant species that does not defend the tree to move in, using beetle made cavities.

(A) The cavities sometimes created in certain species of acacia trees by wood-boring beetles benefit the trees.
 
The passage says those cavities let a nondefending ant species live in the tree, which is part of why the fenced trees did worse. That is not a benefit to the tree.

(B) Browsing animals that would usually feed off certain species of acacia trees do not do so if those trees are inhabited by certain species of ants.
 
Too strong. The passage says the ants defend against browsers, but it also says browsers fed voraciously on unfenced trees, which implies ant defense does not fully prevent browsing.

(C) At least one species of ant that can inhabit certain species of acacia tree does not feed on acacia nectar.
 
Yes. The “fourth species of ant” uses cavities, does not eat acacia nectar, and does not defend the tree.  This is explicitly stated.

(D) Certain species of acacia trees are inhabited by no more than three species of insects.
 
Wrong. The passage describes at least three ant species plus a fourth ant species plus a wood boring beetle, already more than three insect species.

(E) Certain species of acacia trees thrive best when entirely protected from browsing animals.
 
Opposite. The fenced trees (protected from mammals) looked sickly.

Answer: (C)

guddo · Answer

I think, B goes too far. The passage only says the ants  swarm to defend  the tree against browsing animals, not that this defense  successfully prevents  browsing.

In fact, it says browsers “fed voraciously on the unfenced trees,” even though those unfenced trees had ants. That shows ant presence does not guarantee browsers  do not feed  on the trees, so option B is  not supported .

Acacia trees are shrub-like, with some species having swollen thorns t

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GMAT Reading Comprehension (RC) Questions

Acacia trees are shrub-like, with some species having swollen thorns t

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