Biologists have predicted that birds' feather structures vary with habitat temperature, but this hadn't been tested in mountain environments. Ornithol...
GMAT Information and Ideas : (Ideas) Questions
Biologists have predicted that birds' feather structures vary with habitat temperature, but this hadn't been tested in mountain environments. Ornithologist Sahas Barve studied feathers from 249 songbird species inhabiting different elevations—and thus experiencing different temperatures—in the Himalaya Mountains. He found that feathers of high-elevation species not only have a greater proportion of warming downy sections to flat and smooth sections than do feathers of low-elevation species, but high-elevation species' feathers also tend to be longer, providing a thicker layer of insulation.
Which choice best states the main idea of the text?
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| Biologists have predicted that birds' feather structures vary with habitat temperature, but this hadn't been tested in mountain environments. |
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| Ornithologist Sahas Barve studied feathers from 249 songbird species inhabiting different elevations—and thus experiencing different temperatures—in the Himalaya Mountains. |
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| He found that feathers of high-elevation species not only have a greater proportion of warming downy sections to flat and smooth sections than do feathers of low-elevation species, but high-elevation species' feathers also tend to be longer, providing a thicker layer of insulation. |
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Provide Passage Architecture & Core Elements
Main Point: Sahas Barve's study of Himalayan songbirds found that feathers vary with elevation temperature, supporting biologists' predictions.
Argument Flow: The passage establishes that while biologists predicted feather structures would vary with temperature, this hadn't been tested in mountain environments. It then describes how Barve filled this research gap by studying 249 songbird species at different elevations in the Himalayas. Finally, it reports that his findings confirm the prediction—birds at higher, colder elevations have feathers with more insulating features.
Step 2: Interpret the Question Precisely
What's being asked? The main idea of the entire text.
What type of answer do we need? A statement that captures the central message of the passage.
Any limiting keywords? 'best states' means we need the most accurate and complete representation.
Step 3: Prethink the Answer
- The right answer should capture that Barve conducted a study testing a biological prediction
- Mention that his findings supported the prediction about temperature and feather structure
- Acknowledge this provided new evidence for a previously untested environment
- Claims Barve's findings contradict previous predictions
- His findings actually support the predictions
- Accurately captures that Barve found a connection between habitat temperature and feather structure
- Correctly identifies that this finding supports the general prediction
- Misrepresents the findings by saying birds eliminated flat sections entirely
- The passage says they have a greater proportion of downy sections
- Claims the study shows feather length matters more than structure
- The passage presents both as important factors working together