Question

6. Which of the four stages of respiration does NOT take place in mitochondria

A. pyruvate processing

B. glycolysis

C. Citric acid cycle

D. electron transport and oxidative phosphorylation

7. The citric acid cycle is a set of sequential reactions where 2 carbon atoms from Acetyl CoA (that derives from a glucose molecule) are coupled to a 4 carbon molecule. The carbon atoms from Acetyl CoA are released as CO2. Redox reactions and phosphorylation reactions are used to harvest energy in the form of ATP, NADH and FADH2. The product of these reactions is again a 4 carbon molecule that can be coupled with 2 carbon atoms from another Acetyl CoA to repeat the whole process

A. true, this is a correct description of the citric acid cycle

B. false, the citric acid cycle starts with pyruvate as substrate

C. false, the citric acid cycle employs only redox reactions

D. false, the citric acid cycle does not yield NADH

8. The net total output of energy rich molecules from respiration of a molecule of glucose after the citric acid cycle is

A. 2 ATP, 50 NADH, 4 FADH2

B. 2 ATP, 10 NADH, 2 FADH2

C. 4 ATP, 10 NADH, 2 FADH2

D. 4 ATP, 2 NADH, 10 FADH2

9. In the absence of oxygen, cellular respiration switches to fermentation. Fermentation is a set of alternative reactions to complete glycolysis and produce 2 ATP for a glucose molecule, by making sure that the following reagent is available

A. NAD (oxidized electron carrier)

B. EtOH (alcohol)

C. NADH (reduced electron carrier)

D. Acetyl CoA (substrate for citric acid cycle)

Answer 1

6. Option B : Glycolysis

Glycolysis takes place in the cytoplasm of the cell.

7. Option A : True, this is a correct description of the citric acid cycle.

The citric acid cycle yield a 4C molecule oxaloacetate, which is recylced for the next round of TCA. It can be coupled with 2 carbon atoms from another Acetyl CoA to repeat the whole process.

8. Option C : 4 ATP, 10 NADH, 2 FADH2

9. Option A : NAD (oxidized electron carrier)

Fermentation oxidizes NADH to NAD+ ,which is essential for glycolysis to proceed.