The respiratory substrate yielding maximum number of ATP molecules among the following is

Options

A. Ketogenic amino acids
B. glucose
C. amylose
D. glycogen

Explanation

To determine which respiratory substrate yields the maximum number of ATP molecules, we can analyze the options given in the question step by step.

### Step-by-Step Solution:

1. **Understanding Respiratory Substrates**:
- Respiratory substrates are compounds that can be oxidized to release energy for ATP production during cellular respiration. Common substrates include glucose, glycogen, and amylose.

2. **ATP Yield from Glucose**:
- The complete oxidation of one molecule of glucose during aerobic respiration yields a total of 38 ATP molecules. This includes ATP produced during glycolysis and the Krebs cycle.

3. **ATP Yield from Amylose**:
- Amylose is a polysaccharide made up of approximately 2,000 glucose units.
- Since each glucose unit can yield 38 ATP, the total ATP from amylose would be:
\[ \text{Total ATP from Amylose} = 2000 \times 38 = 76,000 \text{ ATP molecules} \]

4. **ATP Yield from Glycogen**:
- Glycogen is another polysaccharide, consisting of about 30,000 glucose units.
- Similar to amylose, each glucose unit yields 38 ATP, so the total ATP from glycogen would be:
\[ \text{Total ATP from Glycogen} = 30000 \times 38 = 1,140,000 \text{ ATP molecules} \]

5. **Comparison of ATP Yields**:
- From the calculations:
- Glucose yields 38 ATP.
- Amylose yields 76,000 ATP.
- Glycogen yields 1,140,000 ATP.
- Clearly, glycogen yields the maximum number of ATP molecules.

6. **Conclusion**:
- Among the given options, the respiratory substrate yielding the maximum number of ATP molecules is **glycogen**.

### Final Answer:
The respiratory substrate yielding the maximum number of ATP molecules is **glycogen**.

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