Question 148·Easy·Inferences
Recent studies suggest that migrating monarch butterflies rely on an internal compass that combines information from the Sun and their circadian (daily) rhythm. In one experiment, researchers kept monarchs indoors under artificial light that was shifted six hours ahead of the natural day–night cycle. When released outdoors, these butterflies began flying west rather than the usual southward direction seen in autumn migration. The researchers concluded that the insects had reset their internal clocks to match the shifted schedule. This result suggests that ______
Which choice most logically completes the text?
For “complete the text” inference questions, first restate in your own words what the study or passage shows—especially the cause-and-effect relationship. Then scan the choices and eliminate any that (1) introduce new ideas not in the passage, (2) are too extreme (words like “always,” “never,” “solely,” “cannot”), or (3) contradict key details. Among the remaining options, choose the one that most directly and moderately expresses what the described result implies, not something the researchers might want to test later.
Hints
Focus on cause and effect
Ask yourself: What did the researchers change in the experiment, and what effect did that change have on the butterflies’ flight direction?
Use the researchers’ conclusion
The researchers say the butterflies “had reset their internal clocks to match the shifted schedule.” Think about how this reset is connected to the fact that the butterflies flew west instead of south.
Watch out for extreme or new ideas
Look for options that introduce new ideas not mentioned in the passage (like specific navigation methods) or that use extreme words such as “cannot,” “solely,” or “never,” and ask whether the passage truly supports such strong claims.
Step-by-step Explanation
Identify what the question is asking
The question asks what the experimental result "suggests"—in other words, what general conclusion the researchers can reasonably draw from the behavior of the butterflies in this study. You must choose the option that is logically supported by the description of the experiment and its outcome, without going beyond the information given.
Summarize the key parts of the experiment
Focus on the important details:
- Monarch butterflies normally migrate south in autumn.
- Researchers kept some monarchs indoors under artificial light that was shifted six hours ahead of the natural day–night cycle.
- These butterflies reset their internal clocks to match that shifted schedule.
- When released outdoors, instead of flying south like normal, they flew west. So: the only thing that changed for these butterflies was the timing of their internal clocks; the real Sun outside was still on the normal schedule.
Infer what the result implies about navigation
The shifted light schedule indoors changed the butterflies’ circadian (daily) rhythm, and this change led them to fly in the wrong direction when they were outside. That means their directional flight is connected to how their internal sense of time lines up with the actual day–night pattern in the environment, not to some unrelated factor.
Match this inference to the answer choices
Now compare each choice to what the experiment actually shows:
- It does not show that artificial light is necessary for migration.
- It does not mention Earth’s magnetic field at all.
- It does not say anything about what happens to butterflies that stay outdoors. The only choice that matches the idea that changing the timing of the butterflies’ internal clocks (while the Sun’s real position stays the same) changes their flight direction is “the directional flight of monarch butterflies depends on their internal circadian clock being synchronized with the Sun.”