The total number of ATP produced during glycolysis is

Analyze the question: It asks for the total number of ATP produced during glycolysis, not the net gain. This wording is the key to the question.

Concept: Glycolysis takes place in the cytoplasm and breaks one glucose molecule (6C) into two pyruvate molecules (3C each).

Step-by-step:

1. Energy investment phase: 2 ATP are used up to phosphorylate glucose (glucose → glucose-6-phosphate, then fructose-6-phosphate → fructose-1,6-bisphosphate).
2. Splitting: The 6-carbon sugar splits into two 3-carbon molecules (G3P).
3. Energy payoff phase: Each 3-carbon molecule produces 2 ATP by substrate-level phosphorylation, so 2 × 2 = 4 ATP produced in total.
4. Net gain: 4 produced − 2 used = 2 ATP net.

So:

• Total (gross) ATP produced = 4
• Net ATP gained = 2

Which one does the question want? It says "total number of ATP produced", which means the gross yield, i.e. 4 molecules. Option B (2) is the net gain, which is the common trap here.

Answer: C. 4 molecules

Exam tip: Look closely at the wording.

• "Total" or "gross" ATP produced → 4
• "Net" ATP gain or yield → 2

Remember it as: "Spend 2, make 4, keep 2."