Plant speciesMycorrhizal hostAverage mass of plants grown in soil containing mycorrhizal fungi (in grams)Average mass of plants grown in soil...
GMAT Information and Ideas : (Ideas) Questions
| Plant species | Mycorrhizal host | Average mass of plants grown in soil containing mycorrhizal fungi (in grams) | Average mass of plants grown in soil treated to kill fungi (in grams) |
|---|---|---|---|
| Corn | yes | 15.1 | 3.8 |
| Marigold | yes | 10.2 | 2.4 |
| Broccoli | no | 7.5 | 7 |
Mycorrhizal fungi in soil benefits many plants, substantially increasing the mass of some. A student conducted an experiment to illustrate this effect. The student chose three plant species for the experiment, including two that are mycorrhizal hosts (species known to benefit from mycorrhizal fungi) and one nonmycorrhizal species (a species that doesn't benefit from and may even be harmed by mycorrhizal fungi). The student then grew several plants from each species both in soil containing mycorrhizal fungi and in soil that had been treated to kill mycorrhizal and other fungi. After several weeks, the student measured the plants' average mass and was surprised to discover that __________
Which choice most effectively uses data from the table to complete the statement?
broccoli grown in soil containing mycorrhizal fungi had a slightly higher average mass than broccoli grown in soil that had been treated to kill fungi.
corn grown in soil containing mycorrhizal fungi had a higher average mass than broccoli grown in soil containing mycorrhizal fungi.
marigolds grown in soil containing mycorrhizal fungi had a much higher average mass than marigolds grown in soil that had been treated to kill fungi.
corn had the highest average mass of all three species grown in soil that had been treated to kill fungi, while marigolds had the lowest.
Step 1: Decode and Map the Passage
| Text from Passage | Analysis |
|---|---|
| "Mycorrhizal fungi in soil benefits many plants, substantially increasing the mass of some." |
|
| "A student conducted an experiment to illustrate this effect." |
|
| "The student chose three plant species for the experiment, including two that are mycorrhizal hosts and one nonmycorrhizal species." |
|
Main Point: A student's experiment on mycorrhizal fungi's effect on plant growth yielded unexpected results that contradicted normal expectations.
Argument Flow: The passage establishes that mycorrhizal fungi typically benefit certain plants, describes a controlled experiment, then indicates the results contained something surprising.
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
- Based on our passage analysis, we know the student expected mycorrhizal hosts (corn and marigold) to benefit from fungi, while the nonmycorrhizal species (broccoli) should not benefit
- Looking at the data, broccoli shows \(\mathrm{7.5g}\) with fungi vs \(\mathrm{7.0g}\) without - a slight benefit instead of no benefit or harm
broccoli grown in soil containing mycorrhizal fungi had a slightly higher average mass than broccoli grown in soil that had been treated to kill fungi.
✓ Correct
- This identifies exactly what would be surprising - broccoli (nonmycorrhizal) actually had slightly higher mass with fungi, contradicting expectations
corn grown in soil containing mycorrhizal fungi had a higher average mass than broccoli grown in soil containing mycorrhizal fungi.
✗ Incorrect
- States that corn had higher mass than broccoli with fungi, which is expected behavior since corn is a mycorrhizal host
marigolds grown in soil containing mycorrhizal fungi had a much higher average mass than marigolds grown in soil that had been treated to kill fungi.
✗ Incorrect
- Describes marigolds showing much higher mass with fungi, which is completely expected since marigolds are mycorrhizal hosts
corn had the highest average mass of all three species grown in soil that had been treated to kill fungi, while marigolds had the lowest.
✗ Incorrect
- Claims corn had highest mass without fungi, but actually broccoli had the highest mass without fungi