A firefly uses specialized muscles to draw oxygen into its lower abdomen through narrow tubes, triggering a chemical reaction whereby...
GMAT Expression of Ideas : (Expression) Questions
A firefly uses specialized muscles to draw oxygen into its lower abdomen through narrow tubes, triggering a chemical reaction whereby the oxygen combines with chemicals in the firefly's abdomen to produce a glow. _______ when the firefly stops drawing in oxygen, the reaction—and the glow—cease.
Which choice completes the text with the most logical transition?
For instance,
By contrast,
Specifically,
In conclusion,
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "A firefly uses specialized muscles to draw oxygen into its lower abdomen through narrow tubes, triggering a chemical reaction whereby the oxygen combines with chemicals in the firefly's abdomen to produce a glow." |
|
| [MISSING TRANSITION] |
|
| "when the firefly stops drawing in oxygen, the reaction—and the glow—cease." |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: Fireflies control their glow by controlling oxygen intake—when they draw in oxygen, they glow; when they stop, the glow ceases.
Argument Flow: The passage establishes how the firefly's glowing mechanism works through oxygen intake and chemical reactions, then shows what happens when that same process is halted, creating a clear cause-and-effect relationship with opposite outcomes.
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
- Looking at our passage analysis, we have two contrasting scenarios: first, the firefly draws oxygen and creates a glow, then we learn about when the firefly stops drawing oxygen and the glow disappears
- These are opposite outcomes from opposite actions
- The missing transition needs to signal that we're about to hear about the flip side of what we just learned
- So the right answer should indicate contrast or opposition between the two scenarios
For instance,
- "For instance" introduces examples or specific cases
- This doesn't fit because the second part isn't an example of the first part—it's the opposite scenario
By contrast,
- "By contrast" signals that we're about to hear something different or opposite
- This perfectly fits our passage structure: first we learn how the glow works, then by contrast, we learn what happens when that process stops
Specifically,
- "Specifically" adds detailed information about the same topic
- The second part doesn't provide more specific details about creating the glow—it describes the opposite situation
In conclusion,
- "In conclusion" wraps up a discussion or argument
- This passage isn't building to a conclusion but rather presenting two sides of the same mechanism