Question

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid.
A. Succinate dehydrogenase is the enzyme, and fumarate is the substrate.
B. Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.
C. Succinate is the substrate, and fumarate is the product.
D. Fumarate is the product, and malonic acid is a noncompetitive inhibitor.
E. Malonic acid is the product, and fumarate is a competitive inhibitor.

Answer 1

Answer:

C. Succinate is the substrate, and fumarate is the product.

Explanation:

Succinate is the substrate of the enzyme Succinate dehydrogenase, and as a product is obtained fumarate.  In this scenario, malonic acid plays the role of a competitive inhibitor because its structure resembles the succinate's, so they compete for the active site of the enzyme.  So,  A option is wrong because fumarate is not the product. B option is wrong too because malonic acid is an inhibitor, not the substrate.  Also, D is incorrect because malonic acid is a COMPETITIVE inhibitor, not a noncompetitive one. Finally, E can´t be true because malonic acid is not product and fumarate is the product, not an inhibitor.