Choose the correct statement

Options

A. respiration is carried out by only leaf cells
B. end product of anaerobic respiration is `CO_2` + Pyruvic acid
C. substrate level phosphorylation occurs when `alpha`-ketoglutaric acid changes to succinic acid
D. dark respiration in plants occurs only in night

Answer

To solve the question "Choose the correct statement," we will analyze each of the four statements provided and determine which one is accurate.

### Step-by-Step Solution:

1. **Evaluate Statement 1**: "Respiration is carried out by only leaf cells."
- This statement is incorrect. Respiration occurs in all parts of the plant, including leaves, stems, and roots.

2. **Evaluate Statement 2**: "End product of anaerobic respiration is CO2 and pyruvic acid."
- This statement is also incorrect. The end products of anaerobic respiration in plants are typically carbon dioxide (CO2) and ethyl alcohol (ethanol), not pyruvic acid.

3. **Evaluate Statement 3**: "Substrate level photophosphorylation occurs when alpha-ketoglutaric acid changes to succinic acid."
- This statement is incorrect as well. Substrate level photophosphorylation occurs during the conversion of succinyl coenzyme A to succinic acid, not with alpha-ketoglutaric acid.

4. **Evaluate Statement 4**: "Dark respiration in plants occurs only at night."
- This statement is correct. Dark respiration refers to the process of respiration that occurs in the absence of light, which typically happens at night.

### Conclusion:
The correct statement is **Option 4**: "Dark respiration in plants occurs only at night."

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