Which one of the following statements is not true?

Options

A. Pollen grains of many species cause severe allergies.
B. Stored pollen in liquid nitrogen can be used in the crop breeding programmes.
C. Tapetum helps in the dehiscence of anther.
D. Exine of pollen grains is made up of sporopollenin.

Answer

To solve the question "Which one of the following statements is not true?" we will analyze each statement one by one to determine its validity.

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- **Statement:** "Pollen grains of many species cause severe allergies."
- **Evaluation:** This statement is true. Pollen grains are known to be a significant cause of allergies, including allergic rhinitis and asthma.

2. **Analyze the Second Statement:**
- **Statement:** "Stored pollen in liquid nitrogen can be used in cooperative programs."
- **Evaluation:** This statement is also true. Liquid nitrogen is used to preserve biological materials, including pollen, for various purposes, including cooperative breeding programs.

3. **Analyze the Third Statement:**
- **Statement:** "Dipter helps in the dehiscence of anther."
- **Evaluation:** This statement is false. The dipter is the innermost layer of the pollen grain and is responsible for nourishing developing pollen grains, not for the dehiscence of the anther. The dehiscence is primarily facilitated by the outer layers of the anther.

4. **Analyze the Fourth Statement:**
- **Statement:** "Excine of pollen grain is made up of sporopollenin."
- **Evaluation:** This statement is true. Sporopollenin is a tough substance that makes up the outer layer (exine) of the pollen grain, providing protection.

### Conclusion:
The statement that is not true is the third statement: "Dipter helps in the dehiscence of anther."

### Final Answer:
**The correct option is C: "Dipter helps in the dehiscence of anther."**

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