QUESTION TEXT: If newly hatched tobacco hornworms in nature…
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.
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