Question

Select all that apply. The outputs from the citric acid cycle are:

1) FADH₂
2) CO₂
3) O₂
4) NADH
5) ATP
6) C2 acetyl group

Answer 1

The outputs from the citric acid cycle are: FADH₂, CO₂, NADH, and ATP (Options 1, 2, 4, and 5). It does not output O₂ or a C2 acetyl group; the acetyl group is consumed during the cycle.

Step-by-step explanation:

The citric acid cycle produces FADH₂, CO₂, NADH, and ATP. During the cycle, an acetyl group is combined with oxaloacetate to form citrate, which is then oxidized, releasing two molecules of CO₂.

Throughout this process, three NAD+ molecules are reduced to NADH, one FAD molecule to FADH₂, and one molecule of ATP (or GTP) is produced through substrate-level phosphorylation.

Notably, O₂ is not an output of the citric acid cycle; it is required for the subsequent oxidative phosphorylation.

Additionally, the C2 acetyl group is not an output as it is consumed during the cycle.

Hence, the correct answers are Options 1, 2, 4, and 5.