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# Australian researchers have discovered electroreceptors (sensory organ

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Australian researchers have discovered electroreceptors (sensory organ  [#permalink]

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19 Jul 2018, 14:15
GMATNinja Can we get an explanation for this passage OAs? It would be of great help.

Thanks.
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Re: Australian researchers have discovered electroreceptors (sensory organ  [#permalink]

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19 Jul 2018, 21:50
Smiti25 wrote:
GMATNinja Can we get an explanation for this passage OAs? It would be of great help.

Thanks.

Hi Smiti
I understand you have asked for expert help and i am not one but just trying to help.

First lets get these facts straight
1) There is an animal by name Ant-eater (because it eats ants or whatever!)
2) It has two kinds of sensory's organs that can locate prey
3) the researches have identified them as electroreceptors and tactile receptors.
4) electroreceptors respond even to smallest of electrical fields where as tactile receptors respond to really strong electrical fields (like 1000 times greater that what electroreceptors respond to)

Now lets approach the questions

1. According to the passage, which of the following is a characteristic that distinguishes electroreceptors from tactile receptors?

(A) The manner in which electroreceptors respond to electrical stimuli its mentioned they respond to weak electrical signals but this dos not gives us the difference between the two receptors.
(B) The tendency of electroreceptors to be found in clustersthe passage merely mentions that electroreceptors but the passage does not say anything about how tactile receptors exist.So we cannot really comment on this and cannot identify any difference with 100% surity.
(C) The unusual locations in which electroreceptors are found in most species.The passage mentions that both the receptors are found on the anteater's snout. So this is infact a similarity between the two receptors.
(D) The amount of electrical stimulation required to excite electroreceptorsThe only difference between electroreceptors from tactile receptors that the author is pointing out is at the amount of electric simulation they respond to. In the passage the author mentions that while electroreceptors respond to "extremely weak electrical fields", the tactile receptors (also present on the anteater’s snout) responds to electrical field strengths about 1,000 times greater that those known to excite electroreceptors.
(E) The amount of nervous activity transmitted to the brain by electroreceptors when they are excitedThe passage just mentions that there is only recording of the transmission of nervous activity to the brain. No mention of the amount of nervous activity that is transmitted. Hence no basis for any comparison.

2. Which of the following can be inferred about the experiment described in the first paragraph?

(A) Researchers had difficulty verifying the existence of electroreceptors in the anteater because electroreceptors respond to such a narrow range of electrical field strengths. The passage did not mention about any difficulties that the researchers might have faced in verifying the existence of the anteaters.
(B) Researchers found that the level of nervous activity in the anteater’s brain increased dramatically as the strength of the electrical stimulus was increased.No mention of this either. In the first paragraph the passage just says that the anteater's snout has some electroreceptors that respond to weak electrical fields and there are some tactile receptors on its snout that respond to extremely strong electrical fields.
(C) Researchers found that some areas of the anteater’s snout were not sensitive to a weak electrical stimulus.Yep! exactly how we summarized the first para in option B above.
(D) Researchers found that the anteater’s tactile receptors were more easily excited by a strong electrical stimulus than were the electroreceptors.The passage mentions that tactile receptors respond to strong electrical fields (about 1,000 times greater than those known to excite electroreceptors. However, the passage doesn't say that it responds easily or more easily. These tactile receptors just respond to strong electrical fields. Thats it!
(E) Researchers tested small areas of the anteater’s snout in order to ensure that only electroreceptors were responding to the stimulus.The passage says "The researchers made this discovery by exposing small areas of the snout to extremely weak electrical fields". Here the passage does not details out about how the researches have conducted the experiment.

3. The author of the passage most probably discusses the function of tactile receptors (lines 7-11) [While it is true that tactile receptors, another kind of sensory organ on the anteater’s snout, can also respond to electrical stimuli, such receptors do so only in response to electrical field strengths about 1,000 times greater than those known to excite electroreceptors.] in order to

(A) eliminate an alternative explanation of anteaters’ response to electrical stimuli.This is our answer. See if he had merely known that anteater has two kinds of sensory organs and both respond to electrical field then it could have been possible that when researchers were applying electrical fields to stimulate electroreceptors may be tactile receptors were responding. In that case the research would be rendered useless. By mentioning the fact that these tactile receptors need 1000 times greater electrical field than what electroreceptors need to respond the author has eliminated the possibility we mentioned above. This information about tactile receptors ensures us that it is indeed the electroreceptors that are responding and not the tactile ones.
(B) highlight a type of sensory organ that has a function identical to that of electroreceptorsThe passage does not mention any of the functions of tactile receptors. So this is irrelevant.
(C) point out a serious complication in the research on electroreceptors in anteaters.What sort of complication?? the passage doesn't mention any and if we are talking about response to electrical fields then that just cannot be a complication because electroreceptors respond to very weak electrical fields and tactile one's to very strong electrical fields and in order to identify electroreceptors the researchers exposed small areas of the snout to extremely weak electrical fields.
(D) suggest that tactile receptors assist electroreceptors in the detection of electrical signals.tactile receptors respond to electrical stimuli that is 1000 times greater than those known to excite electroreceptors. Cant see how tactile receptors can help electroreceptors.
(E) introduce a factor that was not addressed in the research on electroreceptors in anteaters.Cant see how this can be the answer. If the author is introducing any information it has a purpose.

I have explained only 3 answers. If you need help with other 3 also let me know. Happy to help
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Re: Australian researchers have discovered electroreceptors (sensory organ  [#permalink]

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20 Jul 2018, 09:30
shweta234 Thank you for that quick response. I actually got the first 5 correct but the last one wrong. Can you help me out with option D, with proper elimination of every other option? I should be have been more precise, actually. Sorry for the trouble.

Regards,
Smiti
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Re: Australian researchers have discovered electroreceptors (sensory organ  [#permalink]

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20 Jul 2018, 10:41
1
talismaaniac wrote:
The Official Guide for GMAT Review 10th Edition, 2003

Practice Question
Question No.: RC 102 ~ 106
Page: 352

Australian researchers have discovered electroreceptors (sensory organs designed to respond to electrical fields) clustered at the tip of the spiny anteater’s snout. The researchers made this discovery by exposing small areas of the snout to extremely weak electrical fields and recording the transmission of resulting nervous activity to the brain. While it is true that tactile receptors, another kind of sensory organ on the anteater’s snout, can also respond to electrical stimuli, such receptors do so only in response to electrical field strengths about 1,000 times greater than those known to excite electroreceptors.

Having discovered the electroreceptors, researchers are now investigating how anteaters utilize such a sophisticated sensory system. In one behavioral experiment, researchers successfully trained an anteater to distinguish between two troughs of water, one with a weak electrical field and the other with none. Such evidence is consistent with researchers’ hypothesis that anteaters use electroreceptors to detect electrical signals given off by prey; however, researchers as yet have been unable to detect electrical signals emanating from termite mounds, where the favorite food of anteaters live. Still, researchers have observed anteaters breaking into a nest of ants at an oblique angle and quickly locating nesting chambers. This ability quickly to locate unseen prey suggests, according to the researchers, that the anteaters were using their electroreceptors to locate the nesting chambers.

1. According to the passage, which of the following is a characteristic that distinguishes electroreceptors from tactile receptors?

(A) The manner in which electroreceptors respond to electrical stimuli
(B) The tendency of electroreceptors to be found in clusters
(C) The unusual locations in which electroreceptors are found in most species.
(D) The amount of electrical stimulation required to excite electroreceptors
(E) The amount of nervous activity transmitted to the brain by electroreceptors when they are excited --> clear winner, low vs high electrical fields

2. Which of the following can be inferred about the experiment described in the first paragraph?

(A) Researchers had difficulty verifying the existence of electroreceptors in the anteater because electroreceptors respond to such a narrow range of electrical field strengths. --> its no where mentioned that they faced difficulty while doing this.
(B) Researchers found that the level of nervous activity in the anteater’s brain increased dramatically as the strength of the electrical stimulus was increased. --> not at all mentioned
(C) Researchers found that some areas of the anteater’s snout were not sensitive to a weak electrical stimulus. --> correct
(D) Researchers found that the anteater’s tactile receptors were more easily excited by a strong electrical stimulus than were the electroreceptors. --> completely wrong. 180 trap
(E) Researchers tested small areas of the anteater’s snout in order to ensure that only electroreceptors were responding to the stimulus. --> yes they did, but "only" is too strong to conclude

3. The author of the passage most probably discusses the function of tactile receptors (lines 7-11) [While it is true that tactile receptors, another kind of sensory organ on the anteater’s snout, can also respond to electrical stimuli, such receptors do so only in response to electrical field strengths about 1,000 times greater than those known to excite electroreceptors.] in order to

(A) eliminate an alternative explanation of anteaters’ response to electrical stimuli --> thats true. To compare that with existing functionality for response
(B) highlight a type of sensory organ that has a function identical to that of electroreceptors --> the purpose is not this exactly...
(C) point out a serious complication in the research on electroreceptors in anteaters.--> complication is not mentioned.
(D) suggest that tactile receptors assist electroreceptors in the detection of electrical signals. --> 180 trap
(E) introduce a factor that was not addressed in the research on electroreceptors in anteaters.--> irrelevant

4. Which of the following can be inferred about anteaters from the behavioral experiment mentioned in the second paragraph?

(A) They are unable to distinguish between stimuli detected by their electroreceptors and stimuli detected by their tactile receptors.
(B) They are unable to distinguish between the electrical signals emanating from termite mounds and those emanating from ant nests.
(C) They can be trained to recognize consistently the presence of a particular stimulus. --> This is the only inferred option
(D) They react more readily to strong than to weak stimuli.
(E) They are more efficient at detecting stimuli in a controlled environment than in a natural environment.

5. The passage suggests that the researchers mentioned in the second paragraph who observed anteaters break into a nest of ants would most likely agree with which of the following statements?

(A) The event they observed provides conclusive evidence that anteaters use their electroreceptors to locate unseen prey.
(B) The event they observed was atypical and may not reflect the usual hunting practices of anteaters.
(C) It is likely that the anteaters located the ants’ nesting chambers without the assistance of electroreceptors.
(D) Anteaters possess a very simple sensory system for use in locating prey.
(E) The speed with which the anteaters located their prey is greater than what might be expected on the basis of chance alone. --> "quickly" is the term here. It suggests they were quick

6. Which of the following, if true, would most strengthen the hypothesis mentioned in lines 17-19 [Such evidence is consistent with researchers’ hypothesis that anteaters use electroreceptors to detect electrical signals given off by prey]?

(A) Researchers are able to train anteaters to break into an underground chamber that is emitting a strong electrical signal.
(B) Researchers are able to detect a weak electrical signal emanating from the nesting chamber of an ant colony. --> for anteaters to detect signals using electro receptors, the signal have to be weak ones. This option strengthens that.
(C) Anteaters are observed taking increasingly longer amounts of time to locate the nesting chambers of ants.
(D) Anteaters are observed using various angles to break into nests of ants.
(E) Anteaters are observed using the same angle used with nests of ants to break into the nests of other types of prey.

Source : Second mammal with a nose for electricity (New Scientist - 25 Mar 1989)

==============+1 Kudos if you like my reply pls====================================
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Re: Australian researchers have discovered electroreceptors (sensory organ  [#permalink]

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20 Jul 2018, 10:43
Smiti25 wrote:
shweta234 Thank you for that quick response. I actually got the first 5 correct but the last one wrong. Can you help me out with option D, with proper elimination of every other option? I should be have been more precise, actually. Sorry for the trouble.

Regards,
Smiti

Hi, please see my response above if that helps,
pls also credit a kudo to me if it cleared your query...
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Re: Australian researchers have discovered electroreceptors (sensory organ  [#permalink]

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20 Jul 2018, 18:24
Smiti25 wrote:
shweta234 Thank you for that quick response. I actually got the first 5 correct but the last one wrong. Can you help me out with option D, with proper elimination of every other option? I should be have been more precise, actually. Sorry for the trouble.

Regards,
Smiti

6. Which of the following, if true, would most strengthen the hypothesis mentioned in lines 17-19 [Such evidence is consistent with researchers’ hypothesis that anteaters use electroreceptors to detect electrical signals given off by prey]?

Here the passage is asking us to strengthen the hypothesis that anteaters actually use electroreceptors to detect electrical signals(weak signals) given off by its prey.So lets look for options that actually strengthens this fact.

(A) Researchers are able to train anteaters to break into an underground chamber that is emitting a strong electrical signal. Yes researchers can train the anteaters but here we need something to strengthen the fact that anteaters use electrical signals to detect their prey. This option doesn't give us that
(B) Researchers are able to detect a weak electrical signal emanating from the nesting chamber of an ant colony.Here the researchers detect that there are weak electrical signals coming out from the ant colony and as a result the anteaters can detect this signals and reach the prey. This is providing evidence to the fact that anteaters use electric signals to detect their prey and we can conclude this because now we know that these ants give out signals
(C) Anteaters are observed taking increasingly longer amounts of time to locate the nesting chambers of ants.The information about the time taken by the anteaters to locate the nesting chambers of ant is not relevant or useful in showing that these ant eaters use electrical signals to locate their prey.
(D) Anteaters are observed using various angles to break into nests of ants.Yet again the information about the angles anteaters use to break into nests of ants. gives no evidence or clue to conclude that they use electric signals to detect their prey.
(E) Anteaters are observed using the same angle used with nests of ants to break into the nests of other types of prey.Same as option D

I hope this helps
Re: Australian researchers have discovered electroreceptors (sensory organ &nbs [#permalink] 20 Jul 2018, 18:24

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