biology help PLEASE?

Question

how are fermentation and cellular respiration similar..whats the main difference between their starting compound?

Answer 1

Say we use glucose as the energy source.
For fermentation, the glucose will act as both an energy source and terminal electron acceptor (TEA), thus, it will not be oxidized as much as in cellular respiration.
For respiration, the glucose will just be the energy/electron source, and a separate TEA (e.g.: O2 or NO3-) will be used to oxidize the glucose and produce ATP to drive the cell's metabolic activities.
Thus, the two are similar in that they both end up giving the cell ATP (energy), but respiration provides much more than fermentation, since the energy source can be oxidized further in respiration. This suggests that cellular respiration will be performed before fermentation due to the gain in ATP difference.

Hope that helps.