A main idea question about a study tests whether you can tell what the researchers learned, not only what they did. Name the topic, then follow any change in the explanation and ask what the later results show. Predict the finding in one sentence, connecting what the comparison and the follow-up test show. Keep any caution about how much the results explain. Wrong choices often repeat a starting belief or claim more than the findings show.
Hints
- Hint 1
Look for the shift after the opening suspicion. What does the sentence starting with However make the researchers reconsider?
- Hint 2
Connect the salt-exposure result to the added-variant test. What do the plants do in each case, and how does the final caution limit what the study shows?
Step-by-step
Follow the turn and the test
Step 1Separate the topic from the starting explanation
The biologists first suspected that a mutation altered an ion-transport protein, helping coastal tomatoes survive salt. A main idea answer needs the study's finding, not that starting explanation. Where does their thinking change? However sends us to the sequencing result.
- Step 2
Connect the comparison to the test
What do the results show instead? The protein-coding region was nearly identical in both populations, but coastal roots switched the gene on earlier than inland roots after salt exposure. Adding the regulatory variant to inland plants then produced earlier gene activation and increased survival. That test links the variant to both earlier gene use and better survival, so the evidence points to changed timing, not a changed protein.
- Step 3
Limit the finding to what the study supports
Does the variant explain all salt tolerance? The researchers say other genes likely contribute to salt tolerance, so the finding leaves room for other causes. The choice saying controlled entirely ignores that limit. Its claim about every coastal plant treats frequently carried a variant as if all coastal plants had the variant.
- Step 4
Choose the finding rather than the rejected claims
Changes the structure repeats the first suspicion, while the ion-transport gene is unnecessary turns earlier gene use into no need for the gene. Which sentence states the tested link without going too far? The sentence beginning A regulatory DNA variant may help gives earlier gene use without claiming it's the whole cause. Choice B.