Pollen grains can be stored for several years in liquid nitrogen having a temperature of

Options

A. `160^(@)C`
B. `-196^(@)C`
C. `-80^(@)C`
D. `-120^(@)C`

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the temperature at which pollen grains can be stored for several years in liquid nitrogen.

2. **Identifying the Options**: The options provided are:
- A) -160 degrees Celsius
- B) -196 degrees Celsius
- C) -80 degrees Celsius
- D) -120 degrees Celsius

3. **Researching Liquid Nitrogen Temperature**: Liquid nitrogen is commonly used for cryopreservation, and it has a boiling point of approximately -196 degrees Celsius.

4. **Analyzing the Options**:
- Option A (-160°C) is higher than the boiling point of liquid nitrogen.
- Option B (-196°C) matches the boiling point of liquid nitrogen.
- Option C (-80°C) and Option D (-120°C) are significantly higher than the boiling point of liquid nitrogen.

5. **Conclusion**: Since pollen grains can be stored in liquid nitrogen, the correct answer is option B, which is -196 degrees Celsius.

6. **Understanding Cryopreservation**: Cryopreservation is the process of preserving cells, tissues, or any biological constructs by cooling them to very low temperatures, which halts enzymatic and chemical activity that could cause damage.

7. **Final Answer**: The correct answer is **B) -196 degrees Celsius**.

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