Narwhals are shy whales that live in the remote Arctic Ocean. Some of them have a long tusk, like a...
GMAT Information and Ideas : (Ideas) Questions
Narwhals are shy whales that live in the remote Arctic Ocean. Some of them have a long tusk, like a unicorn horn, with sensitive nerves. Narwhals are known for this tusk, but many actually don't have one and its purpose is unknown. One group of scientists came up with a possible purpose in 2014. The scientists suggested that the tusk may help narwhals determine when water around them is likely to start freezing and become dangerous for them. Marine biologist Kristin Laidre disagrees with that idea, though. She reasons that if the narwhal's tusk serves such an important purpose, then it's most likely that ______
Which choice most logically completes the text?
some narwhals would seek a new habitat.
fewer marine animals would also have tusks.
more narwhals would have a tusk.
narwhals would become less shy over time.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'Narwhals are shy whales that live in the remote Arctic Ocean.' |
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| 'Some of them have a long tusk, like a unicorn horn, with sensitive nerves.' |
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| 'Narwhals are known for this tusk, but many actually don't have one and its purpose is unknown.' |
|
| 'One group of scientists came up with a possible purpose in 2014.' |
|
| 'The scientists suggested that the tusk may help narwhals determine when water around them is likely to start freezing and become dangerous for them.' |
|
| 'Marine biologist Kristin Laidre disagrees with that idea, though.' |
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| 'She reasons that if the narwhal's tusk serves such an important purpose, then it's most likely that ______' |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: Scientists proposed that narwhal tusks help detect freezing water, but Laidre questions this theory using logical reasoning about evolutionary importance.
Argument Flow: The passage sets up a scientific puzzle about narwhal tusks, presents one proposed solution (ice detection), then introduces a competing perspective that uses evolutionary logic to question that proposal.
Step 2: Interpret the Question Precisely
This is a fill-in-the-blank question asking us to choose the best logical connector. The answer must create the right relationship between what comes before and after the blank.
Step 3: Prethink the Answer
- Laidre is questioning the scientists' theory by using evolutionary logic
- Her reasoning is: 'IF the tusk serves such an important purpose (like detecting dangerous ice), THEN...' We need to think about what would logically follow
- If something is crucial for survival, natural selection would favor it
- Traits that help animals survive and reproduce become more common in populations over time
- So if tusks were really important for avoiding danger, we'd expect more narwhals to have evolved to have them
- Since the passage tells us 'many actually don't have one,' this suggests the tusk might not be as crucial as the 2014 scientists proposed
- So the right answer should reflect this evolutionary logic - that important survival traits become more widespread in populations
some narwhals would seek a new habitat.
✗ Incorrect
- This suggests narwhals would move to new areas
- Doesn't follow from Laidre's evolutionary logic about trait frequency
fewer marine animals would also have tusks.
✗ Incorrect
- This is about other marine animals having fewer tusks
- Laidre's reasoning is specifically about narwhal populations and evolution
more narwhals would have a tusk.
✓ Correct
- This perfectly completes Laidre's evolutionary reasoning
- If tusks were crucial for survival (detecting dangerous freezing), natural selection would favor narwhals with tusks
- Over time, more narwhals would evolve to have this important survival tool
- Since many narwhals actually lack tusks, this questions whether they're really that important for survival
narwhals would become less shy over time.
✗ Incorrect
- Being less shy has no logical connection to tusk importance
- Laidre's reasoning focuses on evolutionary biology and trait frequency, not behavior changes