Select the incorrect statements:

Options

A. Glucose is the favoured substrate for respiration
B. Acetyl Co-A is the raw material for fatty acid and gibberellic acid synthesis
C. OAA is the raw material for synthesis of alkaloid
D. `alpha`-Ketoglutaric acid is the raw material for synthesis of chlorophyll and cytochromes

Answer

To determine the incorrect statements from the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: Glucose is a favorite substrate for respiration.**
- **Analysis:** This statement is true. Glucose is the primary energy source for cellular respiration, as it is easily broken down through glycolysis, the Krebs cycle, and the electron transport chain (ETS) to produce energy, carbon dioxide, and water.

2. **Statement 2: Acetyl coenzyme A is a raw material for fatty acid and gibberellic acid synthesis.**
- **Analysis:** This statement is also true. Acetyl coenzyme A is a key intermediate in various metabolic pathways, including the synthesis of fatty acids and gibberellic acid, which is a plant hormone.

3. **Statement 3: Oxaloacetic acid is a raw material for the synthesis of alkaloids.**
- **Analysis:** This statement is true as well. Oxaloacetic acid, which is produced in the Krebs cycle, can serve as a precursor for the synthesis of various compounds, including alkaloids.

4. **Statement 4: Alpha-ketoglutaric acid is a raw material for the synthesis of chlorophyll and cytochromes.**
- **Analysis:** This statement is incorrect. Alpha-ketoglutaric acid, which is also a by-product of the Krebs cycle, does not serve as a raw material for the synthesis of chlorophyll or cytochromes. Chlorophyll contains magnesium and is synthesized from different precursors, while cytochromes contain iron and copper.

### Conclusion:
The incorrect statement is **Statement 4**: "Alpha-ketoglutaric acid is a raw material for the synthesis of chlorophyll and cytochromes."

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