While researching a topic, a student has taken the following notes:Mexican tetras are a fish species with two distinct populations.Surface-dwelling...
GMAT Expression of Ideas : (Expression) Questions
While researching a topic, a student has taken the following notes:
- Mexican tetras are a fish species with two distinct populations.
- Surface-dwelling tetras live on the surface and are able to see.
- Cave-dwelling tetras live in total darkness and have lost the ability to see.
- Cave-dwelling tetras have asymmetrical skulls with more sensory receptors on one side than the other.
- These receptors help cave-dwelling tetras navigate in darkness.
The student wants to emphasize a difference between surface-dwelling and cave-dwelling tetras. Which choice most effectively uses relevant information from the notes to accomplish this goal?
Surface-dwelling and cave-dwelling tetras may belong to the same species, but they are quite different.
Cave-dwelling tetras can no longer see but use sensory receptors on their skulls to navigate.
Mexican tetras are a fish species with two distinct populations: surface-dwelling tetras and cave-dwelling tetras.
Surface-dwelling tetras can see, whereas cave-dwelling tetras cannot.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Mexican tetras are a fish species with two distinct populations." |
|
| "Surface-dwelling tetras live on the surface and are able to see." |
|
| "Cave-dwelling tetras live in total darkness and have lost the ability to see." |
|
| "Cave-dwelling tetras have asymmetrical skulls with more sensory receptors on one side than the other." |
|
| "These receptors help cave-dwelling tetras navigate in darkness." |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: Mexican tetras exist as two distinct populations with different characteristics - surface tetras that can see and cave tetras that cannot see but have developed special sensory adaptations.
Step 2: Interpret the Question Precisely
What's being asked? We need to choose which sentence most effectively emphasizes a difference between surface-dwelling and cave-dwelling tetras.
What type of answer do we need? A sentence that highlights a contrast or distinction between the two populations.
Any limiting keywords? "emphasize a difference" - this means we're looking for something that clearly contrasts the two populations, not just describes one or mentions both without contrasting.
Step 3: Prethink the Answer
- To emphasize a difference between the two populations, the correct answer should:
- Mention both surface-dwelling AND cave-dwelling tetras
- Directly contrast them on a specific characteristic
- Use language that highlights the distinction
- The most obvious difference from our notes is vision: surface tetras can see, cave tetras cannot. This is a clear, concrete difference that would effectively emphasize how the populations differ.
Surface-dwelling and cave-dwelling tetras may belong to the same species, but they are quite different.
✗ Incorrect
- States they "may belong to the same species, but they are quite different"
- While it mentions both populations and indicates difference, it's too vague
- "Quite different" doesn't specify what the difference is
Cave-dwelling tetras can no longer see but use sensory receptors on their skulls to navigate.
✗ Incorrect
- Only describes cave-dwelling tetras and their adaptations
- Doesn't mention surface-dwelling tetras at all
- Can't emphasize a difference between two things if you only discuss one of them
Mexican tetras are a fish species with two distinct populations: surface-dwelling tetras and cave-dwelling tetras.
✗ Incorrect
- Simply states there are "two distinct populations" and names them
- Doesn't specify what makes them different from each other
- This is just categorization, not emphasis of difference
Surface-dwelling tetras can see, whereas cave-dwelling tetras cannot.
✓ Correct
- Directly contrasts both populations on the specific trait of vision
- Uses contrast language to clearly signal the difference
- Takes the most significant difference from our notes (vision) and presents it as a direct comparison