GED Science TestLife ScienceMedium
A marine biologist is studying a population of deep-sea hydrothermal vent organisms. These organisms thrive in environments devoid of sunlight, relying instead on chemical energy derived from inorganic compounds released from the vents. Which of the following terms best describes the primary mode of nutrition for these organisms?
- AHeterotroph
- BPhotoautotroph
- CPhotoheterotroph
- DChemoautotroph
Show answer & explanationAnswer & explanation
Correct answer: D. Chemoautotroph
Chemoautotrophs are organisms that produce their own food using chemical energy from the oxidation of inorganic substances (like hydrogen sulfide) rather than light energy. This precisely describes organisms living in deep-sea vents.
Why the other options are wrong
- A. Heterotrophs obtain food by consuming other organisms, which is a consumer role, not a primary producer in this context.
- B. Photoautotrophs use light as an energy source to produce food, which is not applicable in a sunless environment.
- C. Photoheterotrophs use light for energy but obtain carbon from organic compounds, which does not fit the description of self-synthesized food from inorganic sources.
Chemoautotroph
An organism that produces its own food (organic compounds) using energy derived from the oxidation of inorganic chemical compounds, rather than from sunlight.
- Found in environments without sunlight (e.g., deep-sea vents).
- Examples include certain bacteria and archaea.
- Forms the base of chemosynthetic food chains.
Memory trick: Auto-Self, Hetero-Other; Photo-Light, Chemo-Chemical.