PSAT Writing and Language Practice Question 337
Question: 337
Gause's Law: It's a Competition
By the nineteenth and early twentieth centuries, scientists had observed many ecological 1 principles, including the principle of competition. In this principle, different organisms or species compete for a limited supply of a certain resource. Scientists posited that whenever two species are in competition, they will not coexist with constant population sizes. 2 To prevent going extinct, a species can either evolve or develop a new niche—the species's unique role in a certain environment. While this idea had been proposed earlier, biologist Georgy Gause was 3 born in Moscow, Russia, in 1910.
[1] In order to demonstrate this theory, Gause conducted a laboratory experiment. [2] He used two species of Paramecium (a type of microscopic organism) known as P. aurelia and P. caudatum. [3] To test the theory of competitive exclusion, Gause also combined the two species and observed what happened. [4] For the experiment, he created separate groups of each organism as control groups. [5] He provided the control and combined groups with the same amount of food and water and used a sample to determine the population of each species every day. [6] He wanted to see whether the two species would grow equally 4 well or whether, as the principle of competitive exclusion suggests, one group would become dominant and overtake the other. 5
6 The experiment contradicted scientists' expectations. In the control groups, the two species had similar populations to each other. However, in the group that was combined, 7 Gause saw no clear pattern: as the two species competed for resources, P. aurelia emerged as the dominant organism. Initially, the two species grew at a similar rate, but P. aurelia soon surpassed P. caudatum and approached the population levels seen in the individual groups. P. caudatum decreased in population, 8 but it later increased and caused the P. aurelia to go extinct.
Scientists continue to study competitive exclusion today, among plants, animals, and even humans, and Gause's experiments are credited for demonstrating this ecological idea experimentally. 9 Ecologists know that, at least under the controlled conditions of a laboratory, 10 when two species compete for the same resources, one will overtake the other one.
Which choice best maintains the style and tone of the passage?
Correct Answer: A
Explanation:
Note the question! The question asks for the choice that best maintains the style and tone of the passage, so it's testing consistency. The tone of the passage is formal and academic, so eliminate answer choices that are too informal or contain slang words. In addition, the underlined word should reflect the idea that Gause wanted to measure how the populations grew, so it should mean something like "successfully." Keep (A) because well matches the tone of the passage and matches the meaning of "successfully" in context. Although "nicely" can match "successfully," it more closely means "agreeably," which is not quite appropriate in context. Eliminate (B). Eliminate (C) because it is too informal to match the tone of the passage. Eliminate (D) because it is too strong. The passage has a mild tone, whereas wonderfully has a more excited connotation, which is not consistent. The correct answer is (A).