While researching a topic, a student has taken the following notes:Bioluminescence is the emission of light by living organisms.This light...
GMAT Expression of Ideas : (Expression) Questions
While researching a topic, a student has taken the following notes:
- Bioluminescence is the emission of light by living organisms.
- This light is produced by chemical reactions in organisms' cells.
- Jellyfish emit flashes of blue light.
- This behavior serves to startle predators.
- Black dragonfish emit a steady red light.
- This behavior helps them locate prey in deep waters.
The student wants to emphasize a difference between the behavior of jellyfish and that of black dragonfish. Which choice most effectively uses relevant information from the notes to accomplish this goal?
Both jellyfish and black dragonfish are organisms that emit light, which is produced by chemical reactions in these organisms' cells.
Black dragonfish emit a steady red light, which helps them locate prey in deep waters.
Bioluminescence, the emission of light by living organisms, results from chemical reactions in organisms' cells.
Jellyfish emit light to startle predators, whereas black dragonfish do so to locate prey.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Bioluminescence is the emission of light by living organisms." |
|
| "This light is produced by chemical reactions in organisms' cells." |
|
| "Jellyfish emit flashes of blue light." |
|
| "This behavior serves to startle predators." |
|
| "Black dragonfish emit a steady red light." |
|
| "This behavior helps them locate prey in deep waters." |
|
Part B: Provide Passage Architecture & Core Elements
Visual Structure Map:
[DEFINITION: Bioluminescence] → [MECHANISM: Chemical reactions in cells] → [EXAMPLE 1: Jellyfish] → [EXAMPLE 2: Black dragonfish]
Main Point: The notes document how different organisms use bioluminescence for different survival purposes.
Argument Flow: The notes start with a general definition of bioluminescence and its mechanism, then provide two contrasting examples that demonstrate different functions - jellyfish use their light defensively to scare predators, while black dragonfish use theirs offensively to hunt prey.
Step 2: Interpret the Question Precisely
Now that we understand the passage, let's nail down exactly what the question wants from us...
What's being asked? We need to select information that emphasizes a DIFFERENCE between jellyfish and black dragonfish behavior.
What type of answer do we need? A statement that highlights contrasting behaviors or purposes between these two species.
Any limiting keywords? "Difference" is the key constraint - we need contrast, not similarities or general information.
Step 3: Prethink the Answer
- The key difference we identified is PURPOSE: jellyfish use bioluminescence defensively (to startle predators away), while black dragonfish use it for hunting (to locate prey)
- The right answer should present both species and show this functional contrast clearly
- It might also include details like the different light patterns (flashes vs steady) that support these different purposes
- The right answer should directly compare the two species and highlight their different reasons for producing light
Both jellyfish and black dragonfish are organisms that emit light, which is produced by chemical reactions in these organisms' cells.
- Focuses entirely on what jellyfish and black dragonfish have in common
- Emphasizes similarities (both emit light through chemical reactions) rather than differences
- Does the opposite of what the question asks for
Black dragonfish emit a steady red light, which helps them locate prey in deep waters.
- Only discusses black dragonfish behavior
- Provides no comparison or mention of jellyfish
- Cannot emphasize a difference when only one species is discussed
Bioluminescence, the emission of light by living organisms, results from chemical reactions in organisms' cells.
- Gives general information about bioluminescence mechanism
- Mentions neither jellyfish nor black dragonfish specifically
- Provides background context but no species comparison
Jellyfish emit light to startle predators, whereas black dragonfish do so to locate prey.
- Directly contrasts the purposes: jellyfish use light to startle predators vs black dragonfish use light to locate prey
- Uses clear comparative structure with contrasting language to emphasize the difference
- Focuses specifically on the behavioral contrast the question asks for
- Students might be tempted by Choice A because it mentions both species, but that choice emphasizes what they share in common rather than what makes them different