Which of the following statement is incorrect ?

Options

A. All enzymes for Kreb's cycle are present in mitochondrial matrix.
B. In glycolysis, hydrogen acceptor is NAD, that can pick up hydrogen atoms.
C. Glycolysis occurs in both aerobic and aerobic respiration.
D. Oxidative phosphorylation takes place in inner mitochondrial membrane and is organized as ETS.

Answer

To determine which statement is incorrect regarding the Krebs cycle and related processes, we will analyze each option one by one.

### Step-by-Step Solution:

1. **Understanding the Krebs Cycle Location**:
- The Krebs cycle, also known as the TCA (tricarboxylic acid) cycle, primarily occurs in the mitochondrial matrix of eukaryotic cells.
- However, there is an exception: the enzyme succinate dehydrogenase is not located in the mitochondrial matrix; instead, it is bound to the inner mitochondrial membrane.

**Hint**: Remember that while most enzymes of the Krebs cycle are in the matrix, succinate dehydrogenase is an exception.

2. **Evaluating the First Statement**:
- The first statement claims that all enzymes for the Krebs cycle are present in the mitochondrial matrix. Since succinate dehydrogenase is located in the inner mitochondrial membrane, this statement is incorrect.

**Hint**: Identify any exceptions in biological processes that may affect the accuracy of a statement.

3. **Evaluating the Second Statement**:
- The second statement mentions that in glycolysis, the hydrogen acceptor is NAD+. This is correct because NAD+ acts as an electron carrier and accepts hydrogen during glycolysis.

**Hint**: Recall the role of NAD+ in cellular respiration and glycolysis.

4. **Evaluating the Third Statement**:
- The third statement states that glycolysis occurs in both aerobic and anaerobic respiration. This is also correct, as glycolysis does not require oxygen and can occur in both conditions.

**Hint**: Consider the universality of glycolysis in different metabolic pathways.

5. **Evaluating the Fourth Statement**:
- The fourth statement indicates that oxidative phosphorylation takes place in the inner mitochondrial membrane and is organized as the electron transport system. This is correct, as oxidative phosphorylation is indeed associated with the electron transport chain located in the inner mitochondrial membrane.

**Hint**: Link oxidative phosphorylation with the electron transport chain and its location.

### Conclusion:
Based on the analysis, the incorrect statement is the first one, which claims that all enzymes for the Krebs cycle are present in the mitochondrial matrix.

### Final Answer:
The incorrect statement is: **"All enzymes for the Krebs cycle are present in the mitochondrial matrix."**