Which of the following is not the function of iron as nutrient in plant ?

Options

A. Constituent of ferridoxin and cyto-chromes
B. Synthesis of chloroplast protein
C. Activates the enzyme catalase
D. Activates the enzyme carboxylase

Answer

To determine which of the following is not a function of iron as a nutrient in plants, we will analyze the given options step by step.

### Step 1: Understand the Role of Iron in Plants
Iron is an essential micronutrient that plays several critical roles in plant physiology. It is involved in various biochemical processes, including photosynthesis and respiration.

### Step 2: Evaluate Each Option
We will evaluate each option provided to identify which one does not pertain to the function of iron.

1. **Constituent of Ferridoxin and Cytochromes**:
- This statement is true. Iron is a key component of ferridoxin and cytochromes, which are important for electron transport in photosynthesis and respiration.

2. **Synthesis of Chloroplast Protein**:
- This statement is also true. Iron is necessary for the synthesis of proteins in chloroplasts, which are crucial for photosynthesis.

3. **Activates the Enzyme Catalase**:
- This statement is true as well. Iron acts as a cofactor for the enzyme catalase, which helps in the breakdown of hydrogen peroxide in plant cells.

4. **Activates the Enzyme Carboxylase**:
- This statement is false. The activation of the enzyme carboxylase is primarily the function of magnesium, not iron.

### Step 3: Identify the Correct Answer
Based on the evaluation:
- The first three options are functions of iron.
- The fourth option, which states that iron activates the enzyme carboxylase, is incorrect.

Thus, the answer to the question "Which of the following is not the function of iron as a nutrient in plant?" is the fourth option.

### Final Answer
The function that is not associated with iron in plants is **activates the enzyme carboxylase**.

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