CAT 2017 Question Paper | Verbal Slot 1

CAT Questions

Has online preparation for CAT left you feeling all jittery ? Do you find yourself choosing among crossroads of what to prepare and what to skip ?
Worry not! CAT previous year paper will give you the much required direction and practicing these questions will give you a subtle nudge that'll help you move forward in your online CAT Preparation. Don't wait! Start right away with this Reading Comprehension question taken from CAT Question Paper 2017.

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Scientists have long recognised the incredible diversity within a species. But they thought it reflected evolutionary changes that unfolded imperceptibly, over millions of years. That divergence between populations within a species was enforced, according to Ernst Mayr, the great evolutionary biologist of the 1940s, when a population was separated from the rest of the species by a mountain range or a desert, preventing breeding across the divide over geologic scales of time. Without the separation, gene flow was relentless. But as the separation persisted, the isolated population grew apart and speciation occurred.

In the mid-1960s, the biologist Paul Ehrlich - author of The Population Bomb (1968) - and his Stanford University colleague Peter Raven challenged Mayr's ideas about speciation. They had studied checkerspot butterflies living in the Jasper Ridge Biological Preserve in California, and it soon became clear that they were not examining a single population. Through years of capturing, marking and then recapturing the butterflies, they were able to prove that within the population, spread over just 50 acres of suitable checkerspot habitat, there were three groups that rarely interacted despite their very close proximity.

Among other ideas, Ehrlich and Raven argued in a now classic paper from 1969 that gene flow was not as predictable and ubiquitous as Mayr and his cohort maintained, and thus evolutionary divergence between neighbouring groups in a population was probably common. They also asserted that isolation and gene flow were less important to evolutionary divergence than natural selection (when factors such as mate choice, weather, disease or predation cause better-adapted individuals to survive and pass on their successful genetic traits). For example, Ehrlich and Raven suggested that, without the force of natural selection, an isolated population would remain unchanged and that, in other scenarios, natural selection could be strong enough to overpower gene flow...

Question 3 : The author discusses Mayr, Ehrlich and Raven to demonstrate that

1. evolution is a sensitive and controversial topic.
2. Ehrlich and Raven's ideas about evolutionary divergence are widely accepted by scientists.
3. the causes of speciation are debated by scientists.
4. checkerspot butterflies offer the best example of Ehrlich and Raven's ideas about speciation.

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Video Explanation

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Explanatory Answer

This answer is arrived at by elimination. The passage does not describe evolution as ‘sensitive and controversial’. Neither does it state categorically that Ehrlich and Raven's ideas about evolutionary divergence are widely accepted by scientists. There is no evidence to state that checkerspot butterflies offer the best example of Ehrlich and Raven's ideas about speciation.

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The question is "The author discusses Mayr, Ehrlich and Raven to demonstrate that"

Hence, the answer is the causes of speciation are debated by scientists.

Choice C is the correct answer.