QuestionEcology / nutrition types
Chemoautotrophs are those organisms which obtain energy:
- (a) from the oxidation of organic electron donors in the presence of light.
- (b) solely from the oxidation of inorganic electron donors in the presence of light.
- (c) from the oxidation of organic electron donors in the absence of light.
- (d) solely from the oxidation of inorganic electron donors in the absence of light.
Answer: (d) solely from the oxidation of inorganic electron donors in the absence of light.
Chemo = energy from chemical oxidation, not light. Auto = carbon from CO₂, so the electron donors are inorganic (H₂S, NH₃, Fe²⁺, H₂). They work in the absence of light. Options with 'light' are photo-trophs; 'organic donors' are chemo-organotrophs.