Which of the following statements regarding metabolic pathways is incorrect?

Options

A. Many of the steps of glycolysis can run in reverse.
B. Strach, sucrose or glycogen must be hydrolysed before if can enter the glycolysis
C. After fats are digested, glycerol enters glycolysis by forming DHAP
D. After fat digestion, fatty acids can no longer participate in cellular respiration.

Answer

To determine which statement regarding metabolic pathways is incorrect, we will evaluate each of the provided statements one by one.

### Step-by-Step Solution:

1. **Evaluate Statement 1**: "Many of the steps of glycolysis can run in reverse order."
- Glycolysis consists of 10 steps, out of which 3 are irreversible and 7 are reversible. Therefore, this statement is **correct**.

2. **Evaluate Statement 2**: "Starch, sucrose, or glycogen must be hydrolyzed before it can enter glycolysis."
- Starch, sucrose, and glycogen are polysaccharides that must be broken down into glucose before they can enter the glycolytic pathway. This statement is also **correct**.

3. **Evaluate Statement 3**: "After fats are digested, glycerol enters glycolysis by forming DHAP."
- When fats are digested, glycerol can indeed be converted into dihydroxyacetone phosphate (DHAP), which can then enter glycolysis. Thus, this statement is **correct**.

4. **Evaluate Statement 4**: "After fat digestion, fatty acids can no longer participate in cellular respiration."
- This statement is **incorrect**. Fatty acids can undergo beta-oxidation to form acetyl CoA, which can then enter the Krebs cycle for cellular respiration. Therefore, this statement is false.

### Conclusion:
The incorrect statement regarding metabolic pathways is **Statement 4**.

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