During the complete oxidation of glucose, the proportion of ATP formed by substrate-level phosphorylation is ....

Options

A. `100%`
B. `89.5%`
C. `10.5%`
D. `50%`

Answer

To solve the question regarding the proportion of ATP formed by substrate-level phosphorylation during the complete oxidation of glucose, we can follow these steps:

### Step 1: Understand the process of ATP formation
- ATP (adenosine triphosphate) is produced during cellular respiration, which includes glycolysis, the Krebs cycle, and oxidative phosphorylation.
- Substrate-level phosphorylation is a direct way of generating ATP by transferring a phosphate group to ADP (adenosine diphosphate) from a phosphorylated intermediate.

### Step 2: Identify the ATP yield from glucose oxidation
- The complete oxidation of one molecule of glucose typically yields a total of 38 ATP molecules (in eukaryotic cells, this can vary slightly based on the efficiency of the electron transport chain).

### Step 3: Determine ATP from substrate-level phosphorylation
- During glycolysis and the Krebs cycle, substrate-level phosphorylation produces a total of 4 ATP molecules (2 from glycolysis and 2 from the Krebs cycle).

### Step 4: Calculate the proportion of ATP from substrate-level phosphorylation
- To find the proportion of ATP formed by substrate-level phosphorylation, we use the formula:

\[ \text{Proportion of ATP} = \left( \frac{\text{ATP from substrate-level phosphorylation}}{\text{Total ATP produced}} \right) \times 100 \]

- Substituting the values:

\[ \text{Proportion of ATP} = \left( \frac{4}{38} \right) \times 100 \approx 10.5\% \]

### Step 5: Conclusion
- The proportion of ATP formed by substrate-level phosphorylation during the complete oxidation of glucose is approximately **10.5%**.

### Final Answer:
The proportion of ATP formed by substrate-level phosphorylation during the complete oxidation of glucose is **10.5%**.

---