Understanding Context-Dependent Vocabulary and Phrasing in Science Passages - LSAT Reading

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Adapted from "Recent Views as to Direct Action of Light on the Colors of Flowers and Fruits" in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The theory that the brilliant colors of flowers and fruits is due to the direct action of light has been supported by a recent writer by examples taken from the arctic instead of from the tropical flora. In the arctic regions, vegetation is excessively rapid during the short summer, and this is held to be due to the continuous action of light throughout the long summer days. "The further we advance towards the north, the more the leaves of plants increase in size as if to absorb a greater proportion of the solar rays. M. Grisebach says that during a journey in Norway he observed that the majority of deciduous trees had already, at the 60th degree of latitude, larger leaves than in Germany, while M. Ch. Martins has made a similar observation as regards the leguminous plants cultivated in Lapland.” The same writer goes on to say that all the seeds of cultivated plants acquire a deeper color the further north they are grown, white haricots becoming brown or black, and white wheat becoming brown, while the green color of all vegetation becomes more intense. The flowers also are similarly changed: those which are white or yellow in central Europe becoming red or orange in Norway. This is what occurs in the Alpine flora, and the cause is said to be the same in both—the greater intensity of the sunlight. In the one the light is more persistent, in the other more intense because it traverses a less thickness of atmosphere.

Admitting the facts as above stated to be in themselves correct, they do not by any means establish the theory founded on them; and it is curious that Grisebach, who has been quoted by this writer for the fact of the increased size of the foliage, gives a totally different explanation of the more vivid colors of Arctic flowers. He says, “We see flowers become larger and more richly colored in proportion as, by the increasing length of winter, insects become rarer, and their cooperation in the act of fecundation is exposed to more uncertain chances.” (Vegetation du Globe, col. i. p. 61—French translation.) This is the theory here adopted to explain the colors of Alpine plants, and we believe there are many facts that will show it to be the preferable one. The statement that the white and yellow flowers of temperate Europe become red or golden in the Arctic regions must we think be incorrect. By roughly tabulating the colors of the plants given by Sir Joseph Hooker as permanently Arctic, we find among fifty species with more or less conspicuous flowers, twenty-five white, twelve yellow, eight purple or blue, three lilac, and two red or pink; showing a very similar proportion of white and yellow flowers to what obtains further south.

The underlined sentence in the passage tells us that                     .

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Answer

The underlined sentence is "The further we advance towards the north, the more the leaves of plants increase in size as if to absorb a greater proportion of the solar rays." This has nothing to do with the number of leaves on a plant, so "the number of leaves on a tree is related to the latitude in which it is found" cannot be the correct answer. Similarly, nothing is said about moisture levels in the specified sentence, so "leaf size is associated with atmospheric moisture levels" cannot be correct either. Many northern-dwelling plants have small leaves" reverses the relationship being presented in a way that makes it incorrect; northern plants should have large leaves, not small ones. "If you take a plant from a northern climate into a southern climate, its leaves will shrink" derives too much from the statement; nothing is said about a given set of leaves changing size, just a variation amongst the sizes of many different sets of leaves. This leaves us with one remaining answer choice, the correct one: "the further south you travel, the smaller plants’ leaves should be." The specified sentence tells us that if you move north, the leaves of plants you see should get bigger. So, therefore, if you head south, the leaves you see on plants should get smaller. The correct answer states what the sentence is saying in a reverse, but still correct, way.

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