winterschool wrote:
Q2. 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. Difficulty - Hard
C.
’Trait for wing size’ is being used to reach the final conclusion. Trait for shorter wings is observed to be dominate over larger wings. The author jumps to the conclusion that shorter wings are advantageous in obtaining food in the wild.
Going through the options, if we negate Answer Choice C, we can see that if not true, the Answer Choice would completely destroy the conclusion. So without the assumption that the box doesn’t affect the trait for wing size, the conclusion would not hold true.