Although it is intuitively clear that an increase in antipredator behavior lowers an animal’s risk of predation when predators are present, such benefits are not easily demonstrated.

reworded

Even though, act not aggressively when we are in front an animal predator could decrease the risk of aggression by it. All this is not shown clearly by science.

We need to back up this hypothesis further.

Regards

wWhy not 'justified' for 2nd one? Am I missing anything? Demonstrate-justify

In the context indicated, “demonstrated” most nearly means

Moreover, read my explanation above.

regards

as i know we cant apply our knowledge or assumption or thinking which is done in 3 option of question 1

Exactly Sir. You are right.

Do you have a question ?? can we help you ??

Regards

Please explain why C is answer to the 1st question.
There is an assumption which is not mentioned in the given passage.

This effect was convincingly demonstrated by a study in which it was found that partially anesthetized tadpoles were less likely to be captured by dragonfly larvae than were unanesthetized tadpoles.

If tadpoles were partially anesthetized, then they gotta be less likely to occur in the wild. You are more likely to find an animal that is stuffed after relishing a heavy meal than one that is partially unconscious due to being anesthetized for whatever purpose.

Is there any evidence in the passage to suggest that "feeding with more intensity" means being more active? The guppies who are well-fed could be more active in scouting the surroundings and the guppies eating would be lesser active since they are only focusing on food consumption. I thought "activeness" and "feeding with more intensity" weren't related so I discarded the option for that reason.

Is the "non-relation" a correct interpretation in answering the question?

Took me 3:15 min, got all correct.
1st ques was a little time consuming.

can anybody please explain why A is not correct for the first question? I've got B & C, but having a difficult time understanding why A is false. Thanks.

Hi sir, I am little confused on how to eliminate A option and a little problem in understanding. The passage says well-fed guppies are less prone to get attacked because they are more alert/vigilant and hungry guppies are more prone to be attacked as they are not alert because they are not well-fed. But it also says that hungry guppies are "feed with greater intensity". I am unable to understand fact that if they feed with greater intensity then they are not hungry ..then how does this contrast work with well-fed and not well-fed puppies. Like it says hungry guppies and immediately followed by "feed with greater intensity" . If they feed with great intensity why are they hungry? can u plz help

I don't think B answer to question 1 is logically perfect. I think it is just an option to trick the test takers.

The former part of the answer fits well with the context, but the latter one does not. We can say "partially anesthetized" is congruent with fewer activities, but not necessarily "alert". Because it is just an assumption based on the common knowledge that animals must be less alert when anesthetized. But we also have a common knowledge that one could be "partially" anesthetized when taking some surgeries, like tooth extracting, which does not decrease the patients' sensitivity to the environment. On the contrary, some people could be highly stimulated after the surgery when metabolizing anesthetic.

Besides, GRE often devised the questions with answers which are not mentioned in the context. Even the "correct" answer is without B can also be interpreted right by the official explanation. Since GRE is trying to live up to "a logical examination," I think they should be more ALERT when inventing "logic." At least this one is not logically perfect.

Completely agree.
C should be the only correct answer. I reason that the other option indicated as correct is not substantiated by the text. Option B forces one to assume that alertness and activity are both decreased by "partial anaesthesia", whereas the passage only states (or alludes) that partial anaesthesia affects activity. Alternatively, it forces one to assume that decreased activity equates to decreased alertness.

Indeed, alertness is not touched upon as an element in the tadpole study in any way; it is only indicated that the second study also pertains to predation risk but concerns itself with activity.
I cannot find any evidence in the passage to suggest equating reduced activity to reduced alertness, nor any rhetorical device that places the second study as a parallel to the first in such a way that alertness and activiy must also necessarily be parallels.

If anything, B would have been an excellent trap answer. Just because the anaesthesized tadpoles were less active does not mean they were less alert. It is entirely possible that the anaesthesized tadpoles were equally alert but had only their mobility affected. Only their mobility, 'activity', being affected can be reasonably established. I believe drawing any equivalence, correlation or causal relationship between reduced activity and reduced alertness with the information, allusions and rhetoric available in the passage is faulty inference.

Timer missing on this one

Fixed.

For the first one, does "less active" necessarily mean "less alert" in the case of tadpoles? The passage doesn't say anything about the alertness of the tadpoles rather focuses solely on the "active" factor in my understanding. Am I missing something here?