LR Question 6 Explanation
QUESTION TEXT: If newly hatched tobacco hornworms in nature first feed…
QUESTION TYPE: Strengthen
HYPOTHESIS: Scientists think that when tobacco hatchworms eat nightshades first, their taste receptors get used to indioside D, which is only found in nightshades. Then nothing else tastes good.
BACKGROUND: Newborn tobacco hatchworms that eat nightshades first don’t eat any other plants. But if hatchworms eat other plants first, they’ll continue eating nightshades and other plants.
ANALYSIS: The scientists have made a plausible hypothesis, but they haven’t really provided evidence to support their idea. To support this, we ought to test the hypothesis that indioside D and taste are the cause.
For example, we could try putting indioside D in another plant and seeing if hookworms eat it. Or try feeding hookworms nightshades with the indioside D removed. That would help test the hypothesis that indioside D is the real factor.
The right answer supports the taste hypothesis by showing that hookworms change their eating habits when taste is gone.
___________
- This explains nothing. From the stimulus we had no reason to say whether or not some nightshades would be better than others.
- CORRECT. This is incredibly strong evidence. Taste was hypothesized as a cause, and this shows that hatchworms change their eating patterns when taste is removed.
This doesn’t prove that indioside D is the cause of the taste bonding, but this is only a strengthen question – no need to prove the argument 100%. - This explains why tobacco hatchworms might eat nightshades first, but it doesn’t explain why they only eat nightshades after that.
- This weakens the hypothesis. The cause of the hookworm eating patterns might be one of the other chemicals, rather than indioside D.
- It’s highly unlikely that taste receptors would only respond to 1-2 chemicals. We could already assume this was true. And this doesn’t explain anything about indioside D.
More Resources for Strengthen Questions
- Intro Course lesson: This intro course lesson covers Strengthen questions.
- Mastery Seminar lesson: This LR Mastery seminar lesson covers strengthen questions.
Can we eliminate (A) on the basis of reasoning that it is reiterating the fact “its taste receptors become habituated to the chemical indioside D”? Indioside D will be present in all varieties of nightshade plants so there should be no preference, thus, it is consistent with the premise.
Not so much that it’s reiterating that exact sentence (becoming habituated to indioside D), but the rest of your ideas are correct. Nightshades contain indioside D, and we don’t know that there’s any variance between the nightshades. Maybe some contain less, some contain more and maybe the amounts they contain correlate with how good the taste is. But the hypothesis still stands: they contain indioside D, and hornworms like that taste.
So when A tells us that hornworms have no preference between the various nightshades, that doesn’t help us support the hypothesis, because the hypothesis isn’t contingent on variance between nightshades.
Hope that helps! Let me know if you have further questions.