NEET Biology: Energy relations- Number of ATP molecules generated Practice Questions

Correct answer: A — 36

Aerobic respiration of one glucose molecule yields approximately 36 to 38 ATP molecules, depending on the exact method used for ATP synthesis (the standard modern estimate is often 38, incorporating proton gradient effects).

Correct answer: A — 7

NADH generates approximately 2.5 ATP (via oxidative phosphorylation) and FADH2 generates approximately 1.5 ATP. If we consider the direct input to the proton gradient, the yield is based on the relative input. In simplified terms focusing on the energy potential: NADH yields about 2 ATP and FADH2 yields about 1 ATP (or 2 ATP depending on the exact model; focusing on the maximum potential yield derived from the carriers). A direct count focusing on the total potential energy derived from these carriers leads to a higher number than simple substrate-level phosphorylation count.

Correct answer: C — Electron Transport Chain (ETC)

While glycolysis produces a small amount of ATP directly, the Electron Transport Chain (ETC) and oxidative phosphorylation, driven by the carriers generated in the preceding stages, produce the bulk of the ATP.

Correct answer: D — 32

Aerobic respiration yields a total of approximately 32 ATP molecules from the complete breakdown of one molecule of glucose, derived from glycolysis, the Krebs cycle, and oxidative phosphorylation.

Correct answer: A — 3

One molecule of pyruvate is oxidized to Acetyl-CoA, producing 1 NADH per pyruvate. Since two pyruvates are formed from one glucose, 2 NADH are formed in this step.

Correct answer: D — 3

Under standard stoichiometry for ATP synthesis from NADH via the proton gradient mechanism, approximately 2 ATP molecules are generated per NADH molecule.

Correct answer: B — Electron Transport Chain

The Electron Transport Chain (ETC) and Oxidative Phosphorylation, which utilize the products of the Krebs cycle and pyruvate oxidation, generate the vast majority of ATP (approximately 30-34 ATP molecules) compared to the 2 ATP from glycolysis alone.

Correct answer: B — More

Fatty acids yield significantly more energy per carbon atom than glucose, thus aerobic oxidation of fatty acids generates substantially more ATP molecules than glucose metabolism.

Correct answer: A — 3

Glycolysis involves two substrate-level phosphorylation steps, directly yielding 4 ATP molecules (2 at step 1 and 2 at step 7).

Correct answer: A — 4

Anaerobic respiration (fermentation) generates significantly fewer ATP molecules (only 2 per glucose) compared to aerobic respiration (approximately 36-38 per glucose).

Correct answer: A — 4

The conversion of 1 NADH through the ETC typically yields about 2 to 3 ATP molecules via oxidative phosphorylation.

Correct answer: C — The substrate-level phosphorylation phase

ATP is generated directly during the substrate-level phosphorylation phase of glycolysis, where energy is transferred from intermediates to ADP.

Correct answer: D — 2

During anaerobic respiration (fermentation), only the process of glycolysis occurs, which generates a net total of 2 ATP molecules.

Correct answer: D — 2

Glycolysis produces a net of 2 ATP molecules via substrate-level phosphorylation, regardless of the presence of oxygen, as it occurs in the cytoplasm.

Correct answer: D — 4

NADH carries electrons to the ETC. While the exact conversion ratio varies, 1 NADH generally yields about 2-3 ATP via oxidative phosphorylation.