Plant physiologists observed that seedlings grown in greenhouses showed strong growth toward artificial light sources, but when translucent barriers w...
GMAT Information and Ideas : (Ideas) Questions
Plant physiologists observed that seedlings grown in greenhouses showed strong growth toward artificial light sources, but when translucent barriers were placed between the plants and lights, growth patterns became less directional. The researchers hypothesized that the barrier materials were filtering specific light wavelengths essential for phototropic responses. An experiment was designed using two identical groups of seedlings. The first group received direct artificial lighting, while barrier material was positioned between the second group and their light source. The researchers then measured directional growth responses in both groups.
Which finding from the experiment, if true, would most directly support the researchers' hypothesis?
Seedlings with direct lighting showed strong directional growth toward the light source, but seedlings behind the barrier exhibited significantly reduced directional growth patterns.
Neither group of seedlings displayed directional growth toward their light sources, but seedlings with direct lighting grew taller overall than those behind the barrier.
Both groups of seedlings grew equally toward their respective light sources, but seedlings behind the barrier grew more slowly than those with direct lighting.
Seedlings with direct lighting remained relatively stationary, but seedlings behind the barrier showed pronounced growth toward the filtered light source.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Plant physiologists observed that seedlings grown in greenhouses showed strong growth toward artificial light sources" |
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| "but when translucent barriers were placed between the plants and lights, growth patterns became less directional" |
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| "The researchers hypothesized that the barrier materials were filtering specific light wavelengths essential for phototropic responses." |
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| "An experiment was designed using two identical groups of seedlings." |
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| "The first group received direct artificial lighting, while barrier material was positioned between the second group and their light source." |
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| "The researchers then measured directional growth responses in both groups." |
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Provide Passage Architecture & Core Elements
Main Point: Researchers hypothesize that translucent barriers reduce directional plant growth by filtering specific light wavelengths essential for phototropic responses, and they designed an experiment to test this hypothesis.
Argument Flow: The passage moves from an initial observation about plant behavior under direct lighting to a contrasting observation when barriers are introduced. The researchers form a hypothesis about wavelength filtering to explain this difference and design a controlled experiment with two groups to test their explanation.
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
- The researchers' hypothesis is that barrier materials filter specific wavelengths essential for phototropic responses
- For this to be supported, we need results showing: Group 1 (direct lighting) should demonstrate strong directional growth toward the light source, and Group 2 (with barrier) should show reduced directional growth compared to Group 1
- This difference should specifically relate to directional growth patterns, not just overall growth rate
Seedlings with direct lighting showed strong directional growth toward the light source, but seedlings behind the barrier exhibited significantly reduced directional growth patterns.
✓ Correct
- Shows direct lighting leads to strong directional growth and barrier leads to significantly reduced directional growth
- Perfectly matches the hypothesis that barriers filter wavelengths essential for directional responses
Neither group of seedlings displayed directional growth toward their light sources, but seedlings with direct lighting grew taller overall than those behind the barrier.
✗ Incorrect
- Claims neither group showed directional growth toward lights
- Contradicts the hypothesis entirely since direct lighting should still produce directional growth
Both groups of seedlings grew equally toward their respective light sources, but seedlings behind the barrier grew more slowly than those with direct lighting.
✗ Incorrect
- States both groups grew equally toward their light sources
- Directly contradicts the hypothesis since there should be a difference in directional growth if barriers filter essential wavelengths
Seedlings with direct lighting remained relatively stationary, but seedlings behind the barrier showed pronounced growth toward the filtered light source.
✗ Incorrect
- Shows direct lighting group remaining stationary while barrier group shows pronounced directional growth
- Completely opposite of what the hypothesis predicts and would actually disprove their explanation