Question

Chemoorganotrophic heterotroph organisms use

• A. Organic compounds as sources of energy, hydrogen, electrons and carbon
• B. Light energy, organic electron source and organic compounds as its carbon source
• C. Chemical energy, inorganic electron source and CO\(_2\) as its carbon source
• D. Organic compounds as sources of energy, hydrogen, inorganic compounds for electrons and carbon (This option is cut off in one image, but ends like this in another)

Hint:

• Metabolic classification based on:
  • Energy source: Chemo- (chemical), Photo- (light).
  • Electron source: -organo- (organic), -litho- (inorganic).
  • Carbon source: -heterotroph (organic), -autotroph (CO\(_2\)).
• Chemoorganoheterotrophs use organic compounds for energy, electrons, and carbon (e.g., humans metabolizing glucose).

Answer 1

The Correct Option is A

Breaking down the term "Chemoorganotrophic heterotroph" (or simply Chemoorganoheterotroph):

• Chemo-: Derives energy from chemical reactions (oxidation of chemical compounds).
• -organo-: Uses organic compounds as its electron source (and often also as its hydrogen source).
• -heterotroph: Uses organic compounds as its carbon source.

So, a chemoorganoheterotroph uses organic compounds for all three fundamental needs: energy, electrons (and hydrogen), and carbon. Let's analyze the options: (a) "Organic compounds as sources of energy, hydrogen, electrons and carbon": This perfectly matches the definition of a chemoorganoheterotroph. (b) "Light energy...": This would be "Photo-", not "Chemo-". Incorrect. (c) "Chemical energy, inorganic electron source and CO\(_2\) as its carbon source": This describes a chemolithoautotroph. Incorrect. (d) "Organic compounds as sources of energy, hydrogen, inorganic compounds for electrons and carbon": "inorganic compounds for electrons and carbon" contradicts "-organo-" and "-heterotroph". Incorrect. Therefore, option (a) is the correct description. Many common organisms, including most animals, fungi, and many bacteria, are chemoorganoheterotrophs. \[ \boxed{\text{Organic compounds as sources of energy, hydrogen, electrons and carbon}} \]