The cryopreservation of germplasm is carried out at

Options

A. `-50C `
B. `-196 C`
C. `-273C`
D. `0 C`

Answer

### Step-by-Step Solution:

1. **Understanding Cryopreservation**: Cryopreservation is a technique used to preserve cells, organs, and tissues by cooling them to very low temperatures. This process helps maintain the viability of these biological materials for future use.

2. **Definition of Germplasm**: Germplasm refers to the collection of genetic resources of an organism. It is crucial for maintaining genetic diversity and can be preserved for research and breeding purposes.

3. **Importance of Preservation**: Germplasm is preserved to ensure genetic diversity and to safeguard against the loss of genetic material. This is important for agriculture, conservation, and research.

4. **Methods of Preservation**: Germplasm can be preserved in two main ways:
- **In Situ Preservation**: This involves preserving germplasm in its natural environment, such as in biosphere reserves or national parks.
- **Ex Situ Preservation**: This involves preserving germplasm outside its natural habitat, typically in controlled laboratory conditions.

5. **Cryopreservation Process**: When germplasm is preserved ex situ, it is often stored in liquid nitrogen at ultra-low temperatures. The specific temperature used for cryopreservation is -196 degrees Celsius.

6. **Role of Cryoprotectants**: To prevent damage during the freezing process, cryoprotectants such as dimethyl sulfoxide (DMSO) are added. These substances help to rapidly freeze the germplasm and prevent the formation of ice crystals, which can damage the cells.

7. **Conclusion**: The cryopreservation of germplasm is specifically carried out at -196 degrees Celsius, which is the temperature of liquid nitrogen.

### Final Answer:
The cryopreservation of germplasm is carried out at **-196 degrees Celsius**.

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