GED Science TestLife ScienceMedium
A marine biologist is studying a population of deep-sea hydrothermal vent organisms. These organisms live in complete darkness and rely on chemical energy from hydrogen sulfide to produce organic compounds. What term best describes their mode of nutrition?
- AChemoheterotroph
- BChemoautotroph
- CPhotoautotroph
- DPhotoheterotroph
Show answer & explanationAnswer & explanation
Correct answer: B. Chemoautotroph
Chemoautotrophs are organisms that obtain energy by oxidizing inorganic substances (like hydrogen sulfide) and use this energy to synthesize organic compounds from carbon dioxide. This accurately describes the deep-sea organisms at hydrothermal vents, which live without sunlight.
Why the other options are wrong
- A. Chemoheterotrophs obtain both energy and carbon from organic compounds, acting as consumers, which is not how these primary producers function.
- C. Photoautotrophs use sunlight as an energy source, which is not available in deep-sea vents.
- D. Photoheterotrophs use light for energy but obtain carbon from organic compounds, not applicable here.
Chemoautotroph
An organism that synthesizes its own food using energy derived from the oxidation of inorganic chemical compounds.
- Uses inorganic chemicals for energy
- Synthesizes organic compounds (autotroph)
- Does not require sunlight (e.g., deep-sea vents)
Memory trick: Auto-trophs make their own, Hetero-trophs hunt.