Question 164·Medium·Inferences
Marine biologist Lina Ortiz and her team mimicked moonlight to study how coral colonies coordinate mass spawning. In standard trials, faint blue-light pulses were switched on each night starting four nights after the full moon; colonies released eggs and sperm within about an hour of one another, and fertilization rates were high. In a separate series of trials, the team delayed the start of the nightly pulses by two days; colonies staggered their releases over several hours, and fertilization rates declined. The researchers therefore hypothesize that _____
Which choice most logically completes the text?
For hypothesis and inference questions, first identify what changed in the experiment and what result changed with it. Then look for the answer that directly links that changed factor to the changed outcome, without adding new claims, contradicting the passage, or using extreme words like “sole,” “any,” or “completely” that the text does not support.
Hints
Focus on what was different between trials
Ask yourself: In the second series of trials, what did the researchers change compared to the standard trials? Ignore outcomes at first and just focus on the setup.
Connect the change to the results
Now look at how the spawning timing and fertilization success changed between the two setups. What pattern do you see connecting the changed factor to the changed results?
Think about what a hypothesis should do
A good hypothesis should explain why the delayed setup led to more spread-out spawning and lower fertilization. Which answer choice directly explains that connection without exaggerating or contradicting the passage?
Step-by-step Explanation
Identify what the experiment changed
Compare the two trial setups:
- Standard trials: Faint blue-light pulses starting four nights after the full moon.
- Delayed trials: The same kind of pulses, but starting two days later.
The key difference is when the pulses start, not how bright they are or whether there is light at all.
Identify what outcome changed
Now compare the outcomes:
- Standard trials: Colonies release eggs and sperm within about an hour of each other; fertilization rates are high.
- Delayed trials: Colonies stagger releases over several hours; fertilization rates decline.
So, changing the timing of the light made the spawning less synchronized and reduced fertilization success.
Infer what the researchers would conclude
When an experiment changes just one factor (here, the timing of the lunar-like light) and important results worsen (less synchronized spawning, lower fertilization), researchers hypothesize that this factor is important.
So they would conclude that the timing of the lunar-like light cues matters for both coordinating when corals spawn and how successful fertilization is, which matches choice A.