Is this a bad biology question

12. (2 points) Biologists sometimes divide living organisms into two groups: autotrophs and heterotrophs. How do these two groups differ?

A. They use different sources of energy.

B. They use different electron acceptors.

C. They use different sources of carbon (THIS WAS LISTED AS THE ANSWER)

D. They differ in the way they generate ATP.

**BUT WHY ISN'T A THE CORRECT ANSWER AS WELL? Wouldn't they use a different energy source as well?? If not, please explain...

You're right. It's a poor question because answer A is ambiguous. I could be argued that both heterotrophs and autotrophs ultimately depend on the sun for a source of energy, but it could equally well be argued that heterotrophs derive their energy from autotrophs rather than directly from the sun. Besides, the same arguments would apply also to carbon sources, since heterotrophs ultimately obtain their carbon from the air through the intermediary of autotrophs.

Actually it is a good biology question. Autotrophs and heterotrophs are defined based on whether or not they can make their own organic compounds. The "trophy" of an organism only tells its carbon source. Autotrophs get their carbon from CO2 while heterotrophs get their carbon from organic compounds. The source of energy is dictated by the prefix chemo or photo. So for example, a photoautotroph (plants) is an organism that gets its energy from the sun and carbon from CO2. You can however have a photoheterotroph, which would get its energy from the sun and its carbon from organic compounds. This combination seems uncommon but there are bacteria that do this. This flow chart are wikipedia can help elaborate. http://en.wikipedia.org/wiki/File:Troph_…
Hope this helps.