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Difficulty: MediumCommand of Evidence: Textual

Marine biologist Dr. Clara Silva investigated how giant kelp (MacrocystisMacrocystis pyriferapyrifera) forests adapt to marine heatwaves. Silva hypothesized that kelp populations growing in areas with historically high temperature variability possess greater thermal tolerance, allowing them to maintain their growth rates during heatwaves compared to populations from historically stable thermal environments. To test this hypothesis, Dr. Silva and her team exposed kelp samples from both variable-temperature and stable-temperature environments to a simulated heatwave in a controlled laboratory setting. Which finding, if true, would most directly support Dr. Silva’s hypothesis?

  1. A
    During the simulated heatwave, kelp samples from the stable-temperature environment maintained their growth rates, while samples from the variable-temperature environment experienced a significant decline in growth.
  2. B
    Under baseline, non-heatwave temperatures, kelp samples from both environments exhibited identical growth rates.
  3. During the simulated heatwave, kelp samples from the variable-temperature environment showed no significant change in growth rate, whereas samples from the stable-temperature environment showed a marked decrease in growth rate.Answer
  4. D
    Kelp populations in variable-temperature environments are expected to expand their geographic range as ocean temperatures rise globally.

Answer

During the simulated heatwave, kelp samples from the variable-temperature environment showed no significant change in growth rate, whereas samples from the stable-temperature environment showed a marked decrease in growth rate.
The correct option is the one stating that variable-temperature kelp samples maintained growth while stable-temperature samples declined. This result directly supports the researcher's hypothesis by demonstrating that populations from variable thermal environments have higher tolerance to heat stress compared to those from stable environments.

Step-by-Step Solution

1
Identify the main claim/hypothesis of the researcher.
Dr. Silva hypothesizes that kelp from variable-temperature environments has greater thermal tolerance (maintaining growth rates during heatwaves) compared to kelp from stable-temperature environments.
To support the claim, we must look for a finding that demonstrates superior performance under heatwave conditions for the variable-temperature population relative to the stable-temperature population.
2
Evaluate the experimental setup described.
Kelp from both environments were exposed to simulated heatwave conditions.
The evidence must compare the growth rates of both groups during this simulated heatwave.
3
Select the option where the variable-temperature group performs better than the stable-temperature group under heatwave conditions.
The finding that variable-temperature kelp maintained growth while stable-temperature kelp declined in growth.
This directly aligns with the prediction that historically variable environments confer greater thermal tolerance.

Key Concept

Identifying textual evidence that directly supports a specific scientific hypothesis or claim.
Estimated Time:1m 30s
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Topics

Command of Evidence: Textual

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