For over a century, drosophila melanogaster have been used to study

Question

For over a century, drosophila melanogaster have been used to study genetics. Commonly known as fruit flies, drosophila lend themselves well to behavioral studies because they are small and easily handled, have short reproductive cycles, and are easily anesthetized with unsophisticated equipment. In the laboratory, fruit flies are confined in small glass containers to facilitate their anesthetization prior to examination for specific traits. It has been observed by several studies that the trait for short, less-powerful wings is dominate over that for large wings that enable longer flights. Thus, many geneticists theorize that shorter wings give drosophila an advantage in obtaining food sources in the wild.

The theory in the argument above is based on which of the following assumptions?

A. Fruit flies have no need to fly long distances in their search for food sources.

B. The social behaviors exhibited by drosophila indicate that shorter wings give individual flies an advantage in mating.

C. The common practice of confining drosophila to small containers does not affect the trait for wing size.

D. Fruit flies that are anesthetized on a regular basis mate just as frequently as those that are not.

E. The shorter reproductive cycles of drosophila are not influenced by the number of flies in a single container.

RatneshS · Answer

Is it C
usually wings affect the behaviour, what if container affects the wing size? conclusion falls

msk0657 · Answer

IMO A is the correct answer.

Premise 1 : For over a century, drosophila melanogaster have been used to study genetics. Commonly known as fruit flies, drosophila lend themselves well to behavioral studies because they are small and easily handled, have short reproductive cycles, and are easily anesthetized with unsophisticated equipment.

Premise 2: In the laboratory, fruit flies are confined in small glass containers to facilitate their anesthetization prior to examination for specific traits. It has been observed by several studies that the trait for short, less-powerful wings is dominate over that for large wings that enable longer flights.

Conclusion : Thus, many geneticists theorize that shorter wings give drosophila an advantage in obtaining food sources in the wild.

The unstated assumption is that fruit files need not fly for longer flights because the short and less powerful wings dominate the longer flies..

A) Negate : Fruit flies need to fly long distances in their search for food sources. Then the conclusion is weakened that shorter wings doesn't give any advantage for fruit flies for food search.

OA please...will correct if I missed anything...

sarth90 · Answer

I think it has to be C. If keeping the flies in glass containers affect the wing sizes than it's not right to theorise that short wings dominate and are used for sourcing food in wild, as it may happen that they used long wings for this purpose

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sairam595 · Answer

For over a century, drosophila melanogaster have been used to study genetics. Commonly known as fruit flies, drosophila lend themselves well to behavioral studies because they are small and easily handled, have short reproductive cycles, and are easily anesthetized with unsophisticated equipment. In the laboratory, fruit flies are confined in small glass containers to facilitate their anesthetization prior to examination for specific traits. It has been observed by several studies that the trait for short, less-powerful wings is dominate over that for large wings that enable longer flights. Thus, many geneticists theorize that shorter wings give drosophila an advantage in obtaining food sources in the wild.

The theory in the argument above is based on which of the following assumptions?

A. Fruit flies have no need to fly long distances in their search for food sources.

B. The social behaviors exhibited by drosophila indicate that shorter wings give individual flies an advantage in mating.

C. The common practice of confining drosophila to small containers does not affect the trait for wing size.

D. Fruit flies that are anesthetized on a regular basis mate just as frequently as those that are not.

E. The shorter reproductive cycles of drosophila are not influenced by the number of flies in a single container.

option B,D,E talks about reproduction & mating - Irrelevant

down to A & C

Option A is wrong - stimulus says longer wings enable longer flights it doesn't mean that shorter wings does not fly long distances

option C is correct - "In the laboratory, fruit flies are confined in small glass containers to facilitate their anesthetization prior to examination for specific traits. It has been observed by several studies that the trait for short, less-powerful wings is dominate over that for large wings that enable longer flights. Thus, many geneticists theorize that shorter wings give drosophila an advantage in obtaining food sources in the wild."

conclusion is drawn based on the experiment conducted. what if something went wrong during experiment and incorrect conclusions are drawn.
option C eliminates this possibility.

chesstitans · Answer

C is an important and common pattern in assumption questions.
A is just a strengthener. Also, A talks about whether the "Fruit flies have no need to fly long distances" while the argument concerns about the advantage of wings in term of finding food sources.

HG0815 · Answer

IMO OA is C

A. Fruit flies have no need to fly long distances in their search for food sources.
 -> 'Flying long distance' is out of scope. 
 Conclusion is about shorter wings. We have to think about the advantage of shorter wings.
B. The social behaviors exhibited by drosophila indicate that shorter wings give individual flies an advantage in mating.
 -> 'Mating' is out of scope.
 Conclusion is about shorter wings. We have to think about the advantage of shorter wings.
C. The common practice of confining drosophila to small containers does not affect the trait for wing size.
 -> Correct
D. Fruit flies that are anesthetized on a regular basis mate just as frequently as those that are not.
 -> 'Regulat basis mate' is out of scope.
 Conclusion is about shorter wings. We have to think about the advantage of shorter wings.
E. The shorter reproductive cycles of drosophila are not influenced by the number of flies in a single container. 
 -> 'Reproductive cycles' is out of scope.
 Conclusion is about shorter wings. We have to think about the advantage of shorter wings.

JakeRockwell · Answer

Clearly C.It is not A because of the feature of the Assumption that IT HAS TO BE TRUE...

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Nayanhazarika25 · Answer

Please explain why c is the answer.

Anupama_1090 · Answer

Hi experts,
Can any of you please explain why isnt A correct. I know C is correct but I am unable to eliminate A. Did not find the other explainations in the thread convincing!
Thank you.

poojaarora1818 · Answer

For over a century, drosophila melanogaster have been used to study genetics. Commonly known as fruit flies, drosophila lend themselves well to behavioral studies because they are small and easily handled, have short reproductive cycles, and are easily anesthetized with unsophisticated equipment. In the laboratory, fruit flies are confined in small glass containers to facilitate their anesthetization prior to examination for specific traits. It has been observed by several studies that the trait for short, less-powerful wings is dominate over that for large wings that enable longer flights. Thus, many geneticists theorize that shorter wings give drosophila an advantage in obtaining food sources in the wild.

The theory in the argument above is based on which of the following assumptions?

A. Fruit flies have no need to fly long distances in their search for food sources.

B. The social behaviors exhibited by drosophila indicate that shorter wings give individual flies an advantage in mating.

C. The common practice of confining drosophila to small containers does not affect the trait for wing size.

D. Fruit flies that are anesthetized on a regular basis mate just as frequently as those that are not.

E. The shorter reproductive cycles of drosophila are not influenced by the number of flies in a single container.

Hi Experts,  nightblade354 ,  mysterymanrog

Can you pls explain why option C is correct and why not option A? I am still confused.

Thanks in Advance!

Tiffsootmoot8 · Answer

Why is A wrong?

The argument makes weak links between the evidence and conclusion IMO. 
The First weak link is that, it makes a real world conclusion based on a laboratory test  (How can we be sure that real world is similar to the laboratory?) 
The second weak link is - concluding that having shorter wings provides an advantage in obtaining food.  (Why this true is not given to us)

Option A really doesn't help with anything. It doesn't help us close the second weak link. If we negate Option A it becomes "Fruit flies need to fly long distances in their search for food sources." The conclusion doesn't fall apart because it only says that short wings provide an added advantage in obtaining food in wild So if the files need to fly long distance, short wings don't give that added advantage, it doesn't say anything really.

PSKhore · Answer

The correct answer is C. The common practice of confining drosophila to small containers does not affect the trait for wing size.

Explanation:

The argument suggests that shorter wings are advantageous for food acquisition. This assumes that the trait for wing size is not significantly affected by the lab environment (being confined to small containers). If confinement did impact wing size, the observed dominance of shorter wings in the lab might not accurately reflect their advantage in the wild.

Why other options are incorrect:

A. Fruit flies have no need to fly long distances in their search for food sources.
This is a consequence of the theory, not an assumption. The argument infers that short wings are advantageous because they don't need to fly long distances.The assumption is about the lab conditions impacting the trait, not about the flies' behavior in the wild.

B. The social behaviors exhibited by drosophila indicate that shorter wings give individual flies an advantage in mating.
While social behavior might be a factor in mating, the argument focuses on food acquisition. 
This option introduces a different aspect of their lives that is not the focus of the argument.

D. Fruit flies that are anesthetized on a regular basis mate just as frequently as those that are not.
The argument does not touch upon mating frequency or the impact of anesthesia on mating. It focuses on wing size and its relation to food acquisition.

E. The shorter reproductive cycles of drosophila are not influenced by the number of flies in a single container.
The argument does not discuss how reproductive cycles are affected by population size or the laboratory environment.
It focuses on wing size and its connection to food-related flight.

Source: AI Overview

aphapale3 · Answer

answer choice -A is the correct
If they don’t need to fly far, then having short wings isn’t a problem—and might even help

Experts please review this

Bhavita. · Answer

@veritasprep could you please provide official explanation for the same. How will C not been correct it is challenging the premise of the argument which is incorrect

Dereno · Answer

The bone of contention is between options A and option C. This question is a perfect example for understanding inference and assumption. The basis condition sufficient condition vs necessary condition.

Before diving deep into the answer options. Let’s understand the passage. There is a fruit fly  dm  which is used for genetic studies due to some advantages unique to this species- Small size, Easy handling by researchers, Short reproductive cycle, and easy to anaesthesia.

They have mentioned the DM was confined in SMALL CONTAINERS.

Then the subsequent statement throws light on an important trait - Small wings and its use in collecting food source in wild.

Assumption asks us to look for the logical gap or missing link.

Option A - Fruit flies have no need to fly long distances in their search for food sources.

This statement is a perfect conclusion or logical inference, which we can arrive based on the passage. Since, longer wings facilitate longer flights and presence of shorter wings is an Indirect link between food and flight duration. For now let’s keep this aside. Even though, I took a greater time to push this answer out.

let’s visit option C - The common practice of confining drosophila to small containers does not affect the trait for wing size.

If the confinement of DM in small containers have affected the wing size. So, it makes us assume that the earlier ancestral DM might have had a long wing span and hence longer distance. Which contradicts the passage and conclusion eventually.

when we negate the option - the conclusion falls apart. Hence, using this approach we can conclude this is an assumption- necessary condition to be true.

PSKhore · Answer

A. Fruit flies have no need to fly long distances in their search for food sources. 
This statement is not a required assumption; it is a  supporting conclusion . 
The argument's logic is based on applying lab findings to the wild. The necessary assumption is that the lab environment itself didn't create the observed trait. 
Option A would explain  why  the short-wing trait is an advantage, but the argument doesn't need to assume this specific reason to be logically sound. 
It only needs to assume the observation is valid for the wild in the first place.

catcun · Answer

egmat  could you please shed some more light on why A isn't the correct answer?

egmat · Answer

catcun  Choice A is tempting because it seems to support the conclusion, and many test-takers get caught between A and C.

Why A is not the correct answer:

Choice A states that fruit flies have  no need  to fly long distances for food. While this would support the conclusion if true, it's not a  necessary assumption . The argument can still work even if flies sometimes need to fly long distances—perhaps shorter wings provide other advantages (maneuverability, energy efficiency) that outweigh occasional long-distance needs.

Apply the Negation Test to A: 
 
 Negate A: "Fruit flies  DO  need to fly long distances to search for food" 
 Does this destroy the conclusion?  No —short wings could still provide an overall advantage in obtaining food through other means (quicker access, better control in tight spaces, etc.) 
 Since negating A doesn't destroy the argument, A is not a necessary assumption

Why C is the correct answer:

The critical gap in this argument: observations are made in  LABORATORY conditions  (small glass containers), but the conclusion is about advantages in  THE WILD .

We must assume that lab conditions haven't artificially created or favored the short-wing trait. If confinement in small containers favors short wings, then the observed dominance might be an artifact of the experimental setup, not evidence of wild advantages.

Apply the Negation Test to C: 
 
 Negate C: "Confining drosophila to small containers  DOES  affect the trait for wing size" 
 Does this destroy the conclusion?  YES —if lab conditions artificially favor short wings, then the dominance tells us nothing about food-gathering advantages in the wild 
 Since negating C destroys the argument, C is a necessary assumption

For assumption questions, always identify the  logical gap  between evidence and conclusion:
 
  Evidence:  Short wings are dominant (observed in lab containers) 
  Conclusion:  Short wings give advantage in obtaining food (in the wild) 
  Gap:  Lab conditions → Wild advantages 
  Assumption needed:  Lab conditions don't bias the results

The GMAT often includes answer choices that  strengthen  the argument but aren't  necessary  for it. Remember: A necessary assumption  must  be true for the argument to hold—if false, the argument completely falls apart.

For over a century, drosophila melanogaster have been used to study

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For over a century, drosophila melanogaster have been used to study

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