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

Options

A. Glycogen
B. Amylase
C. Ketogenic amino acid
D. Glucose

Answer

To determine the respiratory substrate yielding the maximum number of ATP molecules from the given options (glycosan, myelase, ketogenic amino acid, or glucose), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Cellular Respiration**:
- Cellular respiration is the process by which cells convert glucose and other substrates into energy (ATP). It involves several stages, including glycolysis, the Krebs cycle, and oxidative phosphorylation.

2. **Identifying the Substrates**:
- The options provided are glycosan, myelase, ketogenic amino acid, and glucose. We need to analyze each substrate's potential to yield ATP.

3. **Glucose as a Respiratory Substrate**:
- Glucose is a primary substrate for cellular respiration. During glycolysis, one molecule of glucose is broken down to yield a net gain of 2 ATP molecules. Further oxidation in the Krebs cycle and oxidative phosphorylation can yield approximately 30-32 additional ATP molecules, totaling around 36-38 ATP molecules from one glucose molecule.

4. **Other Substrates**:
- **Glycosan**: This is a form of stored glucose (glycogen). It must first be converted back into glucose before it can be utilized in cellular respiration.
- **Myelase**: This term is not commonly used in the context of respiration; it may refer to a specific enzyme or substrate but does not yield ATP directly.
- **Ketogenic Amino Acids**: These amino acids can be converted into ketone bodies or glucose, but they generally yield fewer ATP molecules compared to glucose when fully oxidized.

5. **Conclusion**:
- Among the options provided, glucose is the substrate that yields the maximum number of ATP molecules during cellular respiration.

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

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