Tent caterpillars’ routes between their nests and potential food

Question

Tent caterpillars’ routes between their nests and potential food sources are marked with chemical traces called pheromones that the caterpillars leave behind. Moreover, routes from food sources back to the nest are marked more heavily than are merely exploratory routes that have failed to turn up a food source. Thus, tent caterpillars are apparently among the insect species that engage in communal foraging, which consists in the conveying of information concerning the location of food to other members of the colony, nest, or hive.

Which one of the following, if true, adds the most support to the argument?

(A) A hungry tent caterpillar is more likely to follow heavily marked routes than lightly marked routes.
(B) Tent caterpillars can detect the presence but not the concentration of pheromones.
(C) Sometimes individual tent caterpillars will not return to the nest until a food source is located.
(D) The pheromones left by tent caterpillars are different from the pheromones left by other animals.
(E) The pheromones that tent caterpillars leave behind are detectable by certain other species of caterpillars.

CrackverbalGMAT · Answer

This is Strengthen the Argument type of question.

Let us break down the argument:
Conclusion: Thus, tent caterpillars are apparently among the insect species that engage in communal foraging, which consists in the conveying of information concerning the location of food to other members of the colony, nest, or hive.

Premises:
• Tent caterpillars’ routes between their nests and potential food sources are marked with chemical traces called pheromones that the caterpillars leave behind.
• Moreover, routes from food sources back to the nest are marked more heavily than are merely exploratory routes that have failed to turn up a food source.

Based on the movements of tent caterpillars between their nests and food sources and the fact that they leave chemical traces on these routes, the conclusion that tent caterpillars engage in communal foraging is drawn. We also get the information that the chemical traces are marked more heavily on routes from food sources back to the nest.

Let us now examine the options.
 Options D and E are the easiest to eliminate. 
The given argument doesn’t refer to other animals and does not make any connection between tent caterpillars and other types of caterpillars or other animals. There is a comparison in the argument between the routes from food sources back to the nests and the exploratory routes; the argument states that the former kind of route is more heavily marked than the latter.

Since Option D makes a comparison between tent caterpillars and other animals, it can be eliminated.
Option E states that the routes left behind by tent caterpillars are detectable by other species of caterpillars. However, the conclusion is that tent caterpillars engage in communal foraging, which involves  conveying information to other members of the colony, nest, or hive . There is no mention of conveying the information to other species. So, Option E can also be eliminated.

Option C states that an individual tent caterpillar doesn’t return to the nest until a food source is located. However, this option doesn’t give us any information to support the idea that tent caterpillars engage in communal foraging. This information could just mean that the individual caterpillar searches for food for itself. There is no mention of leaving a trace for other caterpillars to follow.  So, Option C can also be eliminated.

Option B weakens the argument. One of the premises is that routes from food sources back to the nest are more heavily marked than exploratory routes. If caterpillars cannot detect the concentration of pheromones, they may not necessarily be following a route that has been marked by one of the caterpillars as a trace route to a food source. So, Option B weakens the argument by showing that caterpillars cannot follow a route because they cannot differentiate between a heavily marked route and an exploratory route.  So, Option B can also be eliminated.

Option A supports the idea that tent caterpillars engage in communal foraging by marking routes to food sources more heavily. If a hungry tent caterpillar is more likely to follow a heavily marked route, it is because it most probably expects to find food at the source as the route has been marked by other caterpillars.  Therefore, Option A is the most appropriate option to strengthen the argument.

Jayanthi Kumar.

peanuts · Answer

Tent caterpillars’ routes between their nests and potential food sources are marked with chemical traces called pheromones that the caterpillars leave behind. Moreover, routes from food sources back to the nest are marked more heavily than are merely exploratory routes that have failed to turn up a food source. Thus, tent caterpillars are apparently among the insect species that engage in communal foraging, which consists in the conveying of information concerning the location of food to other members of the colony, nest, or hive.

Premise 1: route from food to nest is more heavily marked with pheromones than exploratory route 
 Premise 2: communal foraging insect convey info about food location to other members of the colony 
 Conclusion: Tent caterpillar communally forages

Which one of the following, if true, adds the most support to the argument?

(A) A hungry tent caterpillar is more likely to follow heavily marked routes than lightly marked routes.  Yes. If a caterpillar is hungry, it could get to food by following the info left behind by other caterpillar 
(B) Tent caterpillars can detect the presence but not the concentration of pheromones.  if so, caterpillar can't differentiate the route to food and route to no-food 
(C) Sometimes individual tent caterpillars will not return to the nest until a food source is located.  we don't care about a particular caterpillar coming back to nest or not. We care about whether caterpillar transfer info about food location to others 
(D) The pheromones left by tent caterpillars are different from the pheromones left by other animals.  It doesn't matter 
(E) The pheromones that tent caterpillars leave behind are detectable by certain other species of caterpillars.  if so, it could communicate with different types of caterpillar, not only with members from its specie. So other type could steal its food?

ShreyasJavahar · Answer

I was stuck between A and D.
D mainly because negating it would mean that the tent caterpillars can't differentiate between the pheromones of their own species and others'. If this differentiation was not possible, then the theory that the species partakes in communal foraging would be void.
Negating A also implies the theory is void, so in this scenario would you terminate D as an answer choice solely because it brings in information about other species and does not concentrate only on the tent caterpillar?

CrackverbalGMAT · Answer

Hi,

Your reasoning is sound and I agree that the two options are similar in their reference to pheromones. However, when it comes down to eliminating one option, D would definitely be eliminated as it digresses from the premises. When it comes down to a choice between two options, the option that has a more direct connection to the premises would be more appropriate. In this question, that is Option A.

The premises emphasize the fact that the caterpillars mark the route from a food source back to the nest more heavily. Option A is aligned more closely to that premise.

I hope the explanation helps:)

Jayanthi Kumar.

unraveled · Answer

Tent caterpillars’ routes between their nests and potential food sources are marked with chemical traces called pheromones that the caterpillars leave behind. Moreover, routes from food sources back to the nest are marked more heavily than are merely exploratory routes that have failed to turn up a food source. Thus, tent caterpillars are apparently among the insect species that engage in communal foraging, which consists in the conveying of information concerning the location of food to other members of the colony, nest, or hive.

Which one of the following, if true, adds the most support to the argument?

Two routes are left behind by TCs.
1. From nest to food source - A to B - as traced by pheromones marked as exploratory.
2. From food source to nest - B to A - as traced by pheromones marked more heavily.

If members follow pheromones i.e. they are able to segregate concentration of pheromones properly and follow heavily marked routes then it would be help support the argument.

(A) A hungry tent caterpillar is more likely to follow heavily marked routes than lightly marked routes. - CORRECT. Exactly what we required.
(B) Tent caterpillars can detect the presence but not the concentration of pheromones. - WRONG. Weakens
(C) Sometimes individual tent caterpillars will not return to the nest until a food source is located. - WRONG. Eventually a weakener.
(D) The pheromones left by tent caterpillars are different from the pheromones left by other animals. - WRONG. Irrelevant at best. However, it may look loke that members of nest might follow routes.
(E) The pheromones that tent caterpillars leave behind are detectable by certain other species of caterpillars. - WRONG. Totally went haywire and thus weakens.

Answer A.

Mavisdu1017 · Answer

Hello expert,
Could you illuminate on D? I think D is saying its pheromones are so unique that only its members can realize, so strengthen the argument “convey information to other members of the colony”. Thanks!

When I thought about it again, I realize D is more like an assumption than a strengthened, so A is better than D. Am I right?

MartyTargetTestPrep · Answer

Let's consider (D).

(D) The pheromones left by tent caterpillars are different from the pheromones left by other animals.

The conclusion of the argument is that "tent caterpillars are apparently among the insect species that engage in communal foraging."

Notice that, if tent caterpillars are "among the insect species that engage in communal foraging," then tent caterpillars are SIMILAR to other insect species in a way.

So, the conclusion involves a similarity between tent caterpillars and other species.

Of course, in that case, what (D) says, "The pheromones left by tent caterpillars are different from the pheromones left by other animals," is neither a strengthener nor a necessary assumption. After all, if the conclusion that tent caterpillars are similar to other insect species, in that tent caterpillars engage in communal foraging, is correct, then it would make sense that tent caterpillars' pheromones would be similar to those of the other species to which tent caterpillars are similar.

Of course, it's also the case that tent caterpillars' pheromones do not have to be similar to those of other species in order for the conclusion to be correct. They could be different, as (D) says.

So, (D) has no clear effect on the argument.

Mavisdu1017 · Answer

Much thanks for your fast response and your input, but I’m still kind of confused and would you mind to explain further?
I think the conclusion is “tent caterpillars are apparently among the insect species that engage in communal foraging and they convey information to their buddies who live in the same colony”, and D “ their pheromones are unique” means only their buddies can recognize and none other species can do so— —> so strengthen “they convey information to their buddies successfully”.

MartyTargetTestPrep · Answer

Notice that the fact that the pheromones are different from other animals' pheromones does not mean that tent caterpillars can detect them. They could be different from other animals' pheromones but undetectable by tent caterpillars or the same as other animals' pheromones and detectable by tent caterpillars. "Different" does not mean "detectable."

Also, the fact that the pheromones are different from other animals' pheromones does not mean that other animals cannot detect them. They could be different from other animals' pheromones but detectable by other animals. "Different" does not mean "undetectable."

So, all the fact that the pheromones are different tells us is that tent caterpillars are different. It doesn't confirm that the pheromones are useful to tent caterpillars or that they use them for foraging for food.

VerbalBot · Answer

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Tent caterpillars’ routes between their nests and potential food

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Tent caterpillars’ routes between their nests and potential food

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