Source: Official Guide Revised GRE 1st Ed. Part 4; Set 2; #8


The author of the passage is primarily concerned

The author of the passage is primarily concerned with Since the Hawaiian Islands have never been connected to other land masses, the great variety of plants in Hawaii must be a result of the long-distance dispersal of seeds, a process that requires both a method of transport and an equivalence between the line ecology of the source area and that of the recipient area. There is some dispute about the method of transport involved. Some biologists argue that ocean and air currents are responsible for the transport of plant seeds to Hawaii. Yet the results of flotation experiments and the low temperatures of air currents cast doubt on these hypotheses. More probable is bird transport, either externally, by accidental attachment of the seeds to feathers, or internally, by the swallowing of fruit and subsequent excretion of the seeds. While it is likely that fewer varieties of plant seeds have reached Hawaii externally than internally, more varieties are known to be adapted to external than to internal transport. discussing different approaches biologists have taken to testing theories about the distribution of plants in Hawaii, discussing different theories about the transport of plant seeds to Hawaii, discussing the extent to which air currents are responsible for the dispersal of plant seeds to Hawaii, resolving a dispute about the adaptability of plant seeds to bird transport, resolving a dispute about the ability of birds to carry plant seeds long distances

2 Explanations


Omobusayo Yusuf

why is A or C not correct?

Jul 30, 2017 • Comment

, Magoosh Tutor

Hi Omobusayo, happy to help :-) In this question, we need to determine the primary purpose of the passage. This means that the answer must provide a concise statement about what the entire passage is about. Answer choice (A) does refer to a particular part of the passage, but the passage as a whole is not concerned with how biologists have tested theories. The passage does discuss different theories, but only one sentence briefly mentions flotation experiments without any details. This can't be the correct answer; it's too narrow.

Answer choice (C) makes the same mistake. The passage briefly mentions air currents, but doesn't talk at all about how they may or may not be responsible for seed transport!

For primary purpose questions, you need to make sure that the answer captures the entire passage. It will be general. It is common for wrong answer choices to be "too narrow." In other words, they focus on one part of the passage but ignore the rest. That is why (A) and (C) are incorrect!

Sep 1, 2017 • Reply


Gravatar Chris Lele, Magoosh Tutor

Oct 3, 2012 • Comment

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