GED Science TestLife ScienceHard
A marine biologist is studying a population of deep-sea hydrothermal vent organisms. These organisms form the base of the food web in this ecosystem, obtaining energy by oxidizing inorganic compounds such as hydrogen sulfide. What term best describes their mode of nutrition?
- AChemoautotroph
- BPhotoautotroph
- CPhotoheterotroph
- DChemoheterotroph
Show answer & explanationAnswer & explanation
Correct answer: A. Chemoautotroph
These organisms produce their own food (autotroph) by using chemical energy from inorganic compounds like hydrogen sulfide (chemo), rather than light energy. This makes them chemoautotrophs, forming the base of food webs in ecosystems without sunlight.
Why the other options are wrong
- B. Photoautotrophs use light energy to produce food (e.g., plants).
- C. Photoheterotrophs use light for energy but obtain carbon from organic compounds.
- D. Chemoheterotrophs obtain both energy and carbon from organic compounds (e.g., animals, fungi).
Chemoautotroph
An organism, typically bacteria or archaea, that produces its own food using energy derived from the oxidation of inorganic chemical compounds, rather than light energy.
- Does not require sunlight.
- Forms the base of food webs in dark environments (e.g., deep sea).
- Utilizes compounds like hydrogen sulfide, ammonia, or iron.
Memory trick: Nutrition: Light or Chemicals for Energy, Self-Made or Other-Fed for Carbon.