1. Which of the following most accurately states the main idea of the passage?

(A) Naked mole rat colonies are the only known examples of cooperatively breeding vertebrate societies.

(B) Naked mole rat colonies exhibit social organization based on a rigid caste system.

(C) Behavior in naked mole rat colonies may well be a close vertebrate analogue to behavior in eusocial insect societies. - The passage begins by stating that "until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial insects like ants and bees, whereby individuals cooperate, sometimes even sacrificing their own opportunities to survive and reproduce, for the good of others. However, such a vertebrate society may exist among underground colonies of the highly social rodent Heterocephalus glaber, the naked mole rat." Then the passage further points out the similarities between the naked mole rat and eusocial insects in the subsequent passages. It points certain differences also but says its behavior still remains closest to a naked mole rat.

(D) The mating habits of naked mole rats differ from those of any other vertebrate species.

(E) The basis for the division of labor among naked mole rats is the same as that among eusocial insects.



2. The passage suggests that Jarvis' work has called into question which of the following explanatory variables for naked mole rat behavior?

(A) Size

(B) Age - Jarvis' work has suggested that differences in growth rates may influence the length of time that an individual performs a task, regardless of its age.

(C) Reproductive status

(D) Rate of growth

(E) Previously exhibited behavior



3. It can be inferred from the passage that the performance of tasks in naked mole rat colonies differs from task performance in eusocial insect societies in which of the following ways?

(A) In naked mole rat colonies, all tasks ate performed cooperatively.

(B) In naked mole rat colonies, the performance of tasks is less rigidly determined by body shape. - 1. Eusocial insect societies have rigid caste systems, each insect's role being defined by its behavior, body shape, and physiology
2. In naked mole rat societies, on the other hand, differences in behavior are related primarily to reproductive status (reproduction being limited to the queen and a few males), body size, and perhaps age


(C) In naked mole rat colonies, breeding is limited to the largest animals.

(D) In eusocial insect societies, reproduction is limited to a single female.

(E) In eusocial insect societies, the distribution of tasks is based on body size.



4. According to the passage, which of the following is a supposition rather than a fact concerning the queen in a naked mole rat colony?

(A) She is the largest member of the colony.

(B) She exerts chemical control over the colony. - queen is the largest member of the colony, and she maintains her breeding status through a mixture of behavioral and, presumably, chemical control

(C) She mates with more than one male.

(D) She attains her status through aggression.

(E) She is the only breeding female.




5. The passage supports which of the following inferences about breeding among Lycaon pictus?

(A) The largest female in the social group does not maintain reproductive status by means of behavioral control.

(B) An individual's ability to breed is related primarily to its rate of growth.

(C) Breeding is the only task performed by the breeding female.

(D) Breeding in the social group is not cooperative.

(E) Breeding is not dominated by a single pair of dogs. - unlike naked mole rats, most cooperatively breeding vertebrates (except the wild dog, Lycaon pictus) are dominated by a pair of breeders rather than by a single breeding female



6. According to the passage, naked mole rat colonies may differ from all other known vertebrate groups in which of the following ways?

(A) Naked mole rats exhibit an extreme form of altruism. - Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial insects like ants and bees, whereby individuals cooperate, sometimes even sacrificing their own opportunities to survive and reproduce, for the good of others. However, such a vertebrate society may exist among underground colonies of the highly social rodent Heterocephalus glaber, the naked mole rat.


(B) Naked mole rats are cooperative breeders.

(C) Among naked mole rats, many males are permitted to breed with a single dominant female.

(D) Among naked mole rats, different tasks are performed at different times in an individual's life.

(E) Among naked mole rats, fighting results in the selection of a breeding female.




7. One function of the third paragraph of the passage is to

(A) state a conclusion about facts presented in an earlier paragraph

(B) introduce information that is contradicted by information in the fourth paragraph

(C) qualify the extent to which two previously mentioned groups might be similar - The two previously mentioned groups are the naked mole rat and the eusocial insects. The third para states to what extent are they similar. It states that: "Eusocial insect societies have rigid caste systems, each insect's role being defined by its behavior, body shape, and physiology. In naked mole rat societies, on the other hand, differences in behavior are related primarily to reproductive status (reproduction being limited to the queen and a few males), body size, and perhaps age."

(D) show the chain of reasoning that led to the conclusions of a specific study

(E) demonstrate that of three explanatory factors offered, two may be of equal significance

Hi TheMechanic
Why is the choice C in Q6 wrong?
Cooperative breeding has evolved many times in vertebrates, but unlike naked mole rats, most cooperatively breeding vertebrates (except the wild dog, Lycaon pictus) are dominated by a pair of breeders rather than by a single breeding female.

Doesn't the sentence mentioned above reflect the fact stated in option C?
(C) Among naked mole rats, many males are permitted to breed with a single dominant female.

Hi gabesc87,

For Question 3: Option B says "In naked mole rat colonies, the performance of tasks is less rigidly determined by body shape". To evaluate this focus on the below to sentences of the passage.:
1. Eusocial insect societies have rigid caste systems, each insect's role being defined by its behavior, body shape, and physiology
2. In naked mole rat societies, on the other hand, differences in behavior are related primarily to reproductive status (reproduction being limited to the queen and a few males), body size, and perhaps age
This implies that eusocial insects have more rigid cast systems and their role is defined by 3 factors including body shape. In naked mole rat, on the other hand, differences in behavior is related PRIMARILY to reproductive status. Body size, age etc are secondary. So, since body shape is a rigid and primary factor for eusocial insects and since, it is a secondary factor for naked mole rats, this automatically implies body shape as a factor is less rigid in mole rats.. Hence, B is correct.

(D) In eusocial insect societies, reproduction is limited to a single female. - No where is this stated in the passage.

Question 7: C: "qualify the extent to which two previously mentioned groups might be similar" - The two previously mentioned groups are the naked mole rat and the eusocial insects. The third para states to what extent are they similar. It states that: "Eusocial insect societies have rigid caste systems, each insect's role being defined by its behavior, body shape, and physiology. In naked mole rat societies, on the other hand, differences in behavior are related primarily to reproductive status (reproduction being limited to the queen and a few males), body size, and perhaps age." Thus, the author is talking about the extent to which these two groups are similar in characteristics. This is what the author is qualifying.

Hope this helps!

For Q.7, answer (C),( qualify the extent to which two previously mentioned groups might be similar)
So when it talks about "the extent to~ similar," this doesn't have to be about both groups being actually similar? Maybe just think it as a comparison concept?
I first excluded this because the paragraph mainly talks about the differences, not similarities

Hi ,
In Q6
We have given that "such a vertebrate society(which exhibits altruism) may exist among underground colonies of the highly social rodent Heterocephalus glaber, the naked mole rat. "
So as in A , i feel like its too extreme that they always exhibits.
Please correct me if i m wrong

Question #6 asks how naked mole rats (NMR) differ from "all other known vertebrate groups." So, we are looking for something about naked mole rats that is completely unique to NMRs when compared to all other known vertebrate species.

Let's look first at (D):

In the third paragraph, the author states that "in naked mole rat societies, on the other hand, differences in behavior are related primarily to reproductive status... body size, and perhaps age." He/she then goes on to explain that the size of a particular NMR is a better indicator of what tasks it will complete than is its age -- the NMR's growth rate influences the time they stay in a given task, "regardless of age."

So, at best the information in (D) is only partially true for NMR's. As stated above, we also need proof that NMRs are the only known vertebrates that exhibit the behavior in question. There is simply no evidence in the passage that this is the case for (D). In the last paragraph, we learn that "the division of labor within social groups is less pronounced among other vertebrates than among naked mole rats," but the author doesn't elaborate on how other vertebrates divide their labor. They could split up tasks based on age, in which case (D) would not be unique to NMRs. For this reason, (D) is out.

Now take a look at (E):

Again, we need to prove that this is a unique attribute of NMRs among all known vertebrate groups.

In the last paragraph, the author states that "most cooperatively breeding vertebrates (except the wild dog, Lycaon pictus) are dominated by a pair of breeders rather than by a single breeding female." These cooperatively breeding species must somehow choose which female gets to breed. The passage doesn't tell us how this decision is made, so we cannot be sure that they do not fight to determine which female becomes the breeder. In addition, we have no idea what is going on with the Lycaon pictus -- maybe they fight to choose a single breeding female, or maybe they do not. Because we do not have this information, we cannot say that NMR's differ from all other vertebrate groups in this way. (E) is out.

Compare this to (A):

The evidence for this answer choice is found in the first paragraph: "Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial insects like ants and bees... However, such a vertebrate society may exist among underground colonies of the highly social rodent Heterocephalus glaber, the naked mole rat."

Here, we learn that scientists did not know of any vertebrates showing an "extreme form of altruism" until they studied NMRs. From this, we can conclude that NMRs are the only known vertebrate group to exhibit this behavior. (A) is the correct answer.

I hope that helps!
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Hi sunny91,
2. The passage suggests that Jarvis' work has called into question which of the following explanatory variables for naked mole rat behavior?

Eusocial insect societies have rigid caste systems, each insect's role being defined by its behavior, body shape, and physiology. In naked mole rat societies, on the other hand, differences in behavior are related primarily to reproductive status (reproduction being limited to the queen and a few males), body size, and perhaps age. --> age is one of the factors in naked mole rat societies

Jarvis' work has suggested that differences in growth rates may influence the length of time that an individual performs a task, regardless of its age. ---> As per Jarvis, age is not a factor that influences differences in behavior in Naked mole rat societies
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We need them to be different from all other 'vertebrate' groups.

Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial insects like ants and bees...

They knew of insects with extreme form of altruism but not a vertebrate. Then they found naked mole rat.
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