Which of the following produces the greatest amount of ATP?

Question

answer choices:

1. glycolysis

2. lactate fermentation

3. gluconeogenesis

4. the Krebs cycle

5. electron transfer phosphorylation

Answer 1

5. electron transfer phosphorylation

Answer 2

1. Glycolysis only produces 2

2. Fermentation just recycles electron acceptors used up in glycolysis

3. Gluconeogenesis deals with forming sugars, and thus uses energy

4. Krebs produces 1 per cycle

5. Phosphorylation produces something like 32 - 36. Basically all the steps in cellular respiration are designed to carry electrons to the electron transport chain, which produces the energy that drives ATP production (phosphorylation = adding phosphorus group to ADP)

Answer 3

1 and 2 produce a net amount of 2 ATP overall. The only difference is that lactate fermentation is just one step more than glycolysis, where the pyruvate is converted into lactate (this step doesn't involve ATP but rather, NAD+)

3 means formation of new glucose from simpler compounds ("gluco" = glucose, "neo" = new, "genesis" = form). This would logically USE ATP instead of producing it since it is a reversal of glycolysis.

4 TCA cycle forms 1 measly ATP per acetyl-coA used. The real energy is still stuck in the electron carriers NADH/H+ and FADH2

5 Since all other choices were ruled out this is the answer. But for completeness' sake, ETC forms the most ATP since most of the energy released from the breakdown of glucose is trapped in the electrons carriers, which is finally released to form ATP by the electron transport chain.