1. Although oxygen does not participate directly in the citric acid cycle, the cycle operates only when O2 is present. Why?

2. List the five coenzymes involved in decarboxylation of pyruvate by PDC.

3. How does the citrate synthase prevent the wasteful hydrolysis of acetyl CoA to acetate and CoA?

4. What is the ratio of the total number of the lipoyl groups of the E2 core in E. coli PDC to that of mammals?

5. British anti-lewisite (BAL), which was designed to counter the effects of the arsenical war gas lewisite, is useful in treating arsenic poisoning. Explain