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Difficulty: MediumLogical Inferences

In marine ecosystems, the dinoflagellate *Noctiluca scintillans* exhibits bioluminescence when physically disturbed by predators. Researchers hypothesized that this bioluminescence acts as a 'burglar alarm,' illuminating the predator and attracting larger secondary predators that consume the primary predator. To test this, researchers placed the copepod *Temora longicornis* (a primary predator of *N. scintillans*) and three-spined stickleback fish (a secondary predator) in tanks containing *N. scintillans*. In dark conditions, stickleback predation on copepods was significantly higher in tanks with bioluminescent *N. scintillans* than in those with a non-bioluminescent mutant strain, suggesting that ______

Which choice most logically completes the text?

  1. A
    bioluminescent organisms in marine environments are generally less vulnerable to predation than non-bioluminescent organisms.
  2. the bioluminescence of *N. scintillans* aids stickleback fish in locating copepods under low-light conditions.Answer
  3. C
    copepods are more active and easier to catch when they are feeding on bioluminescent prey than on non-bioluminescent prey.
  4. D
    stickleback fish prefer to consume *N. scintillans* directly when copepods are not present in the tanks.

Answer

The bioluminescence of *N. scintillans* aids stickleback fish in locating copepods under low-light conditions.
The correct option is supported because the experiment showed that sticklebacks successfully preyed on more copepods in dark conditions only when the dinoflagellates produced bioluminescence. This directly supports the idea that the bioluminescence acts as a beacon, helping the fish locate the copepods in the dark.

Step-by-Step Solution

1
Identify the main premise and hypothesis in the passage.
The passage states that *N. scintillans* bioluminesces when disturbed, and researchers hypothesized this attracts secondary predators (stickleback fish) to consume primary predators (copepods) by illuminating them.
Understanding the setup helps determine what the experimental results should show.
2
Analyze the experimental results.
In dark conditions, stickleback predation on copepods was significantly higher in tanks with bioluminescent *N. scintillans* than in those with a non-bioluminescent mutant strain.
The difference in predation rate must be attributed to the only variable changed, which is the bioluminescence.
3
Draw a logical inference based on the results.
Since predation by sticklebacks (which are secondary predators) on copepods was higher when bioluminescence was present, the bioluminescence must have made the copepods more visible or easier to locate for the sticklebacks in the dark.
This connects the experimental result back to the hypothesis that the bioluminescence aids secondary predators.

Key Concept

Logical Inferences
Estimated Time:1m 30s
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Logical Inferences

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