Freeze tolerant animals have

Options

A. Proline and sorbitol
B. Nucleating proteins
C. Mucilage
D. All the above.

Answer

To solve the question "Freeze tolerant animals have", we will analyze each option provided and determine which is correct based on our understanding of freeze tolerance in animals.

### Step-by-Step Solution:

1. **Understanding Freeze Tolerance**:
- Freeze-tolerant animals are those that can survive in extremely low temperatures, often below the freezing point of water. They have special adaptations that allow them to withstand these harsh conditions.

2. **Analyzing the Options**:
- **Option A: Proline and Sorbitol**:
- Proline and sorbitol are substances that can act as osmoprotectants but they are not specifically known for freeze tolerance. In fact, they can get denatured at very low temperatures.
- **Option B: Nucleating Proteins**:
- Nucleating proteins, also known as antifreeze proteins (AFPs), are crucial for freeze-tolerant animals. They prevent the formation of ice crystals in bodily fluids, allowing the animals to survive freezing temperatures.
- **Option C: Mucilage**:
- Mucilage is a viscous fluid produced by certain plants and microorganisms. It does not play a significant role in the freeze tolerance of animals.
- **Option D: All of the Above**:
- Since options A, C, and D are incorrect based on the analysis, this option cannot be correct.

3. **Conclusion**:
- The only correct answer is **Option B: Nucleating Proteins**, as these proteins are essential for the survival of freeze-tolerant animals in low temperatures.

### Final Answer:
**Freeze tolerant animals have nucleating proteins.**

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