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Biological functions of many plants and animals vary in cycles that are repeated every 24 hours. It is tempting to suppose that alteration in the intensity of incident light is the stimulus that controls these daily biological rhythms. But there is much evidence to contradict this hypothesis.
Which of the following, if known, is evidence that contradicts the hypothesis stated in lines 2-5 above?
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| Biological functions of many plants and animals vary in cycles that are repeated every 24 hours. |
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| It is tempting to suppose that alteration in the intensity of incident light is the stimulus that controls these daily biological rhythms. |
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| But there is much evidence to contradict this hypothesis. |
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"We start with a scientific fact about 24-hour biological cycles, then see a reasonable hypothesis about light controlling these cycles, and finally get told this hypothesis is contradicted by evidence."
"The hypothesis that light intensity controls daily biological rhythms is contradicted by evidence."
"This is actually setting up for the question rather than making a complete argument. The author presents a hypothesis (light controls biological cycles) and claims there's contradictory evidence, but doesn't provide the evidence. The question asks us to identify what would count as contradictory evidence."
Weaken - We need to find evidence that contradicts the hypothesis that light intensity changes control daily biological rhythms
The hypothesis specifically claims that 'alteration in the intensity of incident light' is the stimulus that controls 24-hour biological cycles in plants and animals
To weaken this hypothesis, we need evidence showing that biological rhythms can exist or persist even when light intensity changes are absent, altered, or don't match the 24-hour pattern. We're looking for scenarios where the light-rhythm connection breaks down.