Question

Given below are four respiratory enzymes. Arrange them in the decreasing order of number of carbon atoms present in the substrates they act on.
(A). Fumarase
(B). Aconitase
(C). Enolase
(D). \(\alpha\) - keto glutarate dehydrogenase
Choose the correct answer from the options given below:

• A. (A), (B), (C), (D).
• B. (B), (D), (A), (C).
• C. (B), (A), (D), (C).
• D. (C), (B), (D), (A).

Hint:

Find the substrate of each enzyme and count its carbon atoms.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
We must arrange the enzymes in decreasing order of the number of carbons in their substrates.

Step 2: Substrates
Aconitase acts on citric acid (6 carbons). Alpha-ketoglutarate dehydrogenase acts on alpha-ketoglutaric acid (5 carbons).

Step 3: More substrates
Fumarase acts on fumaric acid (4 carbons). Enolase acts on 2-phosphoglyceric acid in glycolysis (3 carbons).

Step 4: Order
Decreasing order: 6, 5, 4, 3, which is Aconitase, alpha-keto glutarate dehydrogenase, Fumarase, Enolase, that is (B), (D), (A), (C).

Final Answer:
The order is (B), (D), (A), (C). \[ \boxed{\text{(B) }\text{(B), (D), (A), (C).}} \]