Photosynthesis Cellular Respiration 5

Question 1

During vigorous exercise, why does lactic acid build up in muscles?

Accepted Answer

Oxygen delivery is insufficient, forcing cells into anaerobic fermentation to regenerate NAD+

Answer

When oxygen demand exceeds supply, cells perform lactic acid fermentation, converting pyruvate to lactate to regenerate NAD+ and sustain glycolysis.

Question 2

Which cellular respiration stage produces the most ATP per glucose molecule?

Accepted Answer

Oxidative phosphorylation (electron transport chain)

Answer

Oxidative phosphorylation uses the NADH and FADH2 produced in earlier stages to generate ~26–28 of the ~30–32 total ATP per glucose.

Question 3

If a cell's mitochondria are damaged and non-functional, what is the maximum net ATP it can produce from one glucose molecule?

Accepted Answer

2 ATP

Answer

Without functional mitochondria, only glycolysis operates, producing a net gain of 2 ATP per glucose.

Question 4

What is the respiratory quotient (RQ) of a cell oxidizing glucose compared to one oxidizing fats?

Accepted Answer

Glucose RQ = 1.0; fat RQ ≈ 0.7

Answer

Glucose oxidation produces equal moles of CO2 and O2 (RQ=1.0), while fats require more O2 per CO2 released, giving RQ ≈ 0.7.

Question 5

Oligomycin blocks the F0 channel of ATP synthase. What happens to the proton gradient?

Accepted Answer

The proton gradient increases because protons can no longer flow back through ATP synthase

Answer

Blocking proton re-entry through ATP synthase causes the gradient to build up, eventually back-inhibiting the ETC and stalling electron flow.

Photosynthesis Practice Test