A gene cluster of nod and fix factors control the establishment and function of biological nitrogen fixation system in leguminous roots. One of the following is not a function of nod gene, i.e.,

Options

A. Root hair formation
B. Production of leghaemoglobin
C. Synthesis of nitrogenase
D. Curvature of rood hair tip

Answer

To solve the question regarding the functions of the nod gene in the biological nitrogen fixation system in leguminous roots, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context**: The question refers to the nod and fix gene clusters that are crucial for the establishment and functioning of nitrogen fixation in leguminous plants. These genes are associated with specific bacteria, such as Rhizobium, which form symbiotic relationships with leguminous plants.

2. **Identify the Functions of Nod Genes**: The nod genes are known to have several key functions in the nitrogen fixation process:
- **Curvature of Root Hair Tip**: Nod genes help in the curling of the root hair, which facilitates the entry of the bacteria into the plant root.
- **Synthesis of Nitrogenase**: Nod genes are involved in the production of nitrogenase, the enzyme responsible for converting atmospheric nitrogen into a form usable by plants.
- **Production of Leghemoglobin**: Nod genes also play a role in producing leghemoglobin, which helps in maintaining an oxygen concentration suitable for nitrogenase activity.

3. **Analyze the Options**: The options provided in the question are:
- A. Root hair formation
- B. Production of leghemoglobin
- C. Synthesis of nitrogenase
- D. Curvature of root hair tip

4. **Determine the Incorrect Function**: Among the listed functions, the one that is not associated with the nod gene is:
- **Root Hair Formation**: This process is not directly controlled by the nod genes; instead, it is a general plant developmental process.

5. **Conclusion**: Therefore, the correct answer to the question, which identifies the function that is not associated with the nod gene, is **A. Root hair formation**.