GED Science TestLife ScienceMedium
A biologist is studying a newly discovered species of deep-sea bacteria. Preliminary analysis shows that these bacteria thrive in environments completely lacking sunlight and oxygen, utilizing chemical compounds from hydrothermal vents as their sole energy source. This organism's primary mode of nutrition is best described as:
- AHeterotrophic
- BPhotoautotrophic
- CChemoautotrophic
- DPhotoheterotrophic
Show answer & explanationAnswer & explanation
Correct answer: C. Chemoautotrophic
Chemoautotrophs are organisms that produce their own food (autotrophic) using chemical reactions (chemo) as their energy source, rather than sunlight. This perfectly describes bacteria at hydrothermal vents.
Why the other options are wrong
- A. Heterotrophs obtain energy by consuming other organisms or organic matter, which is not how these bacteria are described as obtaining their *sole* energy.
- B. Photoautotrophs use sunlight as an energy source (e.g., plants, algae), which is not present in deep-sea vents.
- D. Photoheterotrophs use sunlight for energy but obtain carbon from organic compounds, which doesn't fit the 'sole energy source' from chemical compounds.
Chemoautotroph
An organism, typically a bacterium or archaeon, that produces its own food (is autotrophic) by using energy derived from the oxidation of inorganic chemical compounds, rather than from sunlight.
- Energy source: inorganic chemical reactions.
- Carbon source: carbon dioxide (CO2).
- Common in environments without sunlight, like deep-sea vents.
Memory trick: Autotrophs make their own, Heterotrophs hunt for food.