Which of the following of the following statement related to Kreb's cycle is not correct ?

Options

A. There is only reaction in Kreb's cycle where `FAD^+` is reduced to `FADH_2`
B. During conversion of succinyl CoA to succinic acid, a molecule of GTP is synthesized.
C. The cycle starts with reaction of acetyl CoA with pyruvic acid to form 6 C citric acid.
D. There are three reaction in the cycle where `NAD^+` is reduced to `NADH^+H^+`

Answer

To determine which statement related to the Krebs cycle is not correct, we can analyze each of the provided statements step by step.

### Step-by-Step Solution:

1. **Understanding the Krebs Cycle**: The Krebs cycle, also known as the TCA (Tricarboxylic Acid) cycle, is a crucial metabolic pathway that occurs in the mitochondria. It involves the conversion of acetyl-CoA into carbon dioxide and energy carriers (NADH and FADH2).

2. **Analyzing the Statements**:
- **Statement 1**: "The cycle starts with the condensation of acetyl-CoA with oxaloacetate to form citrate."
- This statement is correct. The Krebs cycle begins when acetyl-CoA combines with oxaloacetate to form citrate.

- **Statement 2**: "During the conversion of succinyl-CoA to succinic acid, a molecule of GTP is synthesized."
- This statement is also correct. The conversion of succinyl-CoA to succinate produces GTP (or ATP, depending on the cell type).

- **Statement 3**: "The cycle starts with the reaction of Acetyl-CoA with Pyruvic Acid."
- This statement is incorrect. The Krebs cycle starts with acetyl-CoA reacting with oxaloacetate, not pyruvic acid. Pyruvic acid is converted into acetyl-CoA before entering the Krebs cycle.

- **Statement 4**: "There are three reactions in the cycle where NAD+ is reduced to NADH."
- This statement is correct. There are indeed three steps in the Krebs cycle where NAD+ is reduced to NADH.

3. **Conclusion**: The statement that is not correct regarding the Krebs cycle is Statement 3: "The cycle starts with the reaction of Acetyl-CoA with Pyruvic Acid."

### Final Answer:
The incorrect statement related to the Krebs cycle is: "The cycle starts with the reaction of Acetyl-CoA with Pyruvic Acid."

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