Four respiratory enzymes are given below. Arrange them in increasing order of the carbon number of the substrates on which they act
Enolase (ii) Aconitase
(iii) fumerase (iv) Alcohol dehydrogenase

Options

A. II, IV, III, I
B. IV, I, II, III
C. I, IV, III, II
D. IV, I, III, II

Answer

To solve the problem of arranging the four respiratory enzymes in increasing order of the carbon number of the substrates on which they act, we will analyze each enzyme and its corresponding substrate.

### Step-by-Step Solution:

1. **Identify the Enzymes and Their Substrates:**
- **Enolase**: This enzyme acts on 2-phosphoglycerate, which is a 3-carbon compound.
- **Aconitase**: This enzyme acts on citrate, which is a 6-carbon compound.
- **Fumarase**: This enzyme acts on fumarate, which is a 4-carbon compound.
- **Alcohol Dehydrogenase**: This enzyme acts on ethanol, which is a 2-carbon compound.

2. **List the Carbon Numbers:**
- Enolase: 3 carbons
- Aconitase: 6 carbons
- Fumarase: 4 carbons
- Alcohol Dehydrogenase: 2 carbons

3. **Arrange the Carbon Numbers in Increasing Order:**
- The order of carbon numbers from least to greatest is:
- Alcohol Dehydrogenase (2 carbons)
- Enolase (3 carbons)
- Fumarase (4 carbons)
- Aconitase (6 carbons)

4. **Final Arrangement:**
- The increasing order of the enzymes based on the carbon number of their substrates is:
- Alcohol Dehydrogenase (4)
- Enolase (1)
- Fumarase (3)
- Aconitase (2)

Thus, the correct sequence is **4, 1, 3, 2**.