Choose the incorrect statement regarding `N_(2)` metabolism

Options

A. 16 ATPs are required for conversion of one molecule of nitrogen into ammonia
B. Nodule formation requires cytokinin and auxin
C. All twenty amino acid are formed from glutamic acid by transamination
D. Leghaemoglobin in synthesised by host with the help of bacteria

Answer

To determine the incorrect statement regarding nitrogen (N₂) metabolism, we will analyze each option step by step.

### Step 1: Analyze the First Statement
**Statement:** 16 ATPs are required for conversion of one molecule of nitrogen into ammonia.

- **Explanation:** The process of nitrogen fixation involves the conversion of nitrogen gas (N₂) into ammonia (NH₃). According to the nitrogen fixation equation, 16 ATP molecules are indeed required to convert one molecule of nitrogen into two molecules of ammonia. Thus, this statement is **correct**.

### Step 2: Analyze the Second Statement
**Statement:** Nodule formation requires cytokinin and auxin.

- **Explanation:** Nodule formation in legumes involves the interaction between the roots of the host plant and nitrogen-fixing bacteria (like Rhizobium). Cytokinins and auxins are plant hormones that play a crucial role in this process. Therefore, this statement is also **correct**.

### Step 3: Analyze the Third Statement
**Statement:** All 20 amino acids are formed from glutamic acid by transamination.

- **Explanation:** Transamination is a process where the amino group from one amino acid is transferred to a keto acid. While glutamic acid is a key amino acid involved in the synthesis of some amino acids, not all 20 amino acids are formed solely from glutamic acid through transamination. This statement is **incorrect** because only a subset of amino acids can be synthesized this way, not all 20.

### Step 4: Analyze the Fourth Statement
**Statement:** Leg haemoglobin is synthesized by the host with the help of the bacteria.

- **Explanation:** Leg haemoglobin is indeed synthesized in the root nodules of legumes and serves as an oxygen scavenger to protect the nitrogenase enzyme from oxygen, which is detrimental to its function. This statement is **correct**.

### Conclusion
The incorrect statement regarding N₂ metabolism is the third statement: "All 20 amino acids are formed from glutamic acid by transamination."

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