Experiment: To study circadian rhythm, rats were kept in constant darkness for two weeks. Their activity levels were monitored using motion sensors.Observation: The rats maintained a ~24-hour activity cycle despite no light cues.Question: What does this show?
Correct answer: B. Circadian rhythms are internally regulated by biological clocks.
- A. External light is necessary for circadian rhythms to function.
- B. Circadian rhythms are internally regulated by biological clocks.
- C. Darkness stops circadian rhythms from occurring.
- D. Motion sensors affect circadian rhythm patterns in rats.
Explanation
The correct answer is that circadian rhythms are internally regulated by biological clocks. The experiment showed that the rats maintained a 24-hour activity cycle despite being in constant darkness, indicating that their circadian rhythms were not dependent on external light cues. The other options are incorrect because they misinterpret the results of the experiment or introduce irrelevant factors like sleep disruption or halting of biological activity.
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About Scientific Reasoning
Scientific reasoning evaluates hypotheses through observations, variables, controls, measurements and experimental results. Questions involve identifying independent and dependent variables, recognising a fair test, interpreting tables or graphs, distinguishing evidence from opinion, and deciding whether data supports, rejects or leaves a hypothesis unresolved.
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