Which of the following is not a role or function of nitrogen

Options

A. Major constituents of proteins, nucleic acids, vitamins and hormones,
B. Its deficiency causes yellowing of older leaves (chlorosis)
C. Its deficiency causes purple colouration in shoot axis surface
D. Its deficiency causes premature fall of leaf and flowerbuds.

Explanation

**Step-by-Step Solution:**

1. **Understanding Nitrogen's Role in Plants:**
- Nitrogen is an essential nutrient for plants and is classified as a macronutrient, meaning it is required in larger amounts for plant growth and development.

2. **Identifying Functions of Nitrogen:**
- Nitrogen is a major component of proteins, nucleic acids (DNA and RNA), vitamins, and hormones. These components are crucial for various physiological functions in plants.

3. **Recognizing Symptoms of Nitrogen Deficiency:**
- When plants lack sufficient nitrogen, they exhibit several deficiency symptoms:
- **Chlorosis:** Yellowing of older leaves due to insufficient chlorophyll production.
- **Premature Leaf and Flower Bud Drop:** The plant may shed leaves and buds prematurely.
- **Stunted Growth:** The overall growth of the plant may be hindered.

4. **Analyzing the Options:**
- **Option A:** States that nitrogen is a major constituent of proteins, nucleic acids, vitamins, and hormones. This is correct.
- **Option B:** States that nitrogen deficiency causes yellowing of older leaves (chlorosis). This is also correct.
- **Option C:** Claims that nitrogen deficiency causes purple coloration in the shoot axis. This is incorrect, as purple coloration is typically associated with phosphorus deficiency.
- **Option D:** States that nitrogen deficiency causes premature fall of leaves and flower buds. This is correct.

5. **Conclusion:**
- The option that does not correctly describe a role or function of nitrogen is **Option C**, as it pertains to phosphorus deficiency, not nitrogen.

**Final Answer: C (its deficiency causes purple coloration in shoot axis)**

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