GRE Subject Test: Biology : Understanding Trophic Energy

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #1 : Understanding Trophic Energy

A bacterium is found to survive off of organic molecules created by other organisms. It relies on these as both carbon and energy sources. Which term best describes this bacterium?

Possible Answers:




None of these


Correct answer:



Autotrophs use  for their carbon source, while heterotrophs use organic compounds from other organisms. Chemotrophs use chemical bonds as their energy source, while phototrophs use light. Combining these ideas we can come up with various terms to describe an organism's nutrition. The bacterium in this question stated to rely on organic chemicals from other organisms as a carbon and energy source. This makes it a chemoheterotroph.

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