Question 121·Easy·Command of Evidence
Marine biologist Dr. Lee observed that a reef-building coral species emits a vivid glow under ultraviolet light after sunset. Dr. Lee hypothesizes that this nighttime bioluminescence attracts plankton, supplying the coral with extra food when photosynthesis cannot occur.
Which finding, if true, would most directly support Dr. Lee’s hypothesis?
For “which finding would most directly support the hypothesis” questions, first paraphrase the hypothesis and break it into its key claims (here: nighttime glow → attracts plankton → extra food at night). Then look for an answer that provides measurable, comparative evidence that lines up with those claims (e.g., more of X when Y is present than when it is not, under similar conditions). Eliminate choices that only give background detail, mention related concepts without testing the hypothesis, or describe situations outside the specific conditions the hypothesis is about (such as daytime when the claim is about night).
Hints
Focus on what the hypothesis is claiming
Underline the parts of the hypothesis that say what the glow is supposed to do. What effect is Dr. Lee suggesting the glow has, and on what?
Look for cause-and-effect style evidence
You want a finding that would make it reasonable to say, “Because the coral glows at night, something changes near it.” Which answer actually measures that “something”?
Check for a comparison under similar conditions
For evidence to be strong, it should compare conditions with glow versus without glow (or another clear contrast) while keeping other factors similar, like species and time of day. Which option does that?
Step-by-step Explanation
Restate the hypothesis in your own words
Dr. Lee’s hypothesis has two key ideas:
- At night, the coral glows (bioluminescence).
- This glow attracts plankton, which means more plankton come near the coral at night to provide extra food when photosynthesis cannot happen.
So any supporting evidence should connect nighttime glow with increased plankton nearby.
Decide what kind of evidence would test the hypothesis
To directly support the idea that the glow attracts plankton, you’d want a finding that:
- Measures plankton levels (not just glow or enzymes), and
- Compares situations with glow vs. without glow, ideally under similar conditions (same species, same reef, same time of night).
If the hypothesis is right, you’d expect more plankton near glowing coral than near non-glowing coral in comparable conditions.
Evaluate each answer choice against that standard
Go through the options and ask: Does this show that glowing coral at night has more plankton nearby than non-glowing coral (or than at other times)?
- Any choice that doesn’t mention plankton is unlikely to directly support the hypothesis.
- Any choice that doesn’t make a useful comparison (glowing vs. non-glowing, or night vs. day) is also weak support at best.
Identify the choice that directly links glow and higher nighttime plankton
Only choice B, “Plankton concentrations near the glowing coral are significantly higher at night than near non-glowing coral of the same species,” gives clear, comparative evidence that when the coral glows at night, there are more plankton around it than around similar coral that does not glow—this directly supports the idea that the glow attracts extra food at night, so B is the correct answer.