Usable energy available from respiration is

Options

A. 0.1
B. 0.3
C. 0.4
D. 0.5

Answer

### Step-by-Step Solution:

1. **Understanding Respiration**: Respiration is the process by which glucose is oxidized to produce energy. The complete oxidation of one mole of glucose results in the formation of carbon dioxide and water.

2. **Energy Released**: During the complete oxidation of one mole of glucose, approximately 690,000 calories of energy are released.

3. **Energy Utilization**: Out of the total energy released, only a portion is used to form high-energy phosphate bonds in ATP. Specifically, about 10,000 calories are required to form one mole of ATP.

4. **ATP Production**: In the process of respiration, approximately 36 to 38 moles of ATP are produced from the oxidation of one mole of glucose.

5. **Energy Loss**: It is important to note that not all the energy released is captured in the form of ATP. A significant amount of energy is lost as heat during the respiration process.

6. **Usable Energy Calculation**: Approximately 52% of the total energy released during respiration is captured in the form of ATP. To express this as a fraction, 52% can be converted to a decimal, which is 0.52.

7. **Final Answer**: Therefore, the usable energy available from respiration, expressed in terms of ATP, is approximately 0.5 (or 50%).