which one of the following statements is false in respect of viability of mammalian sperm ?

Options

A. Sperms must be concentrated in a thick suspension
B. Sperm is viable for only up to 24 hours
C. Survlval of sperm depends on the pH of the medium and is more active in alkaline medium
D. Viability of sperm is determined by its motility

Answer

To determine which statement is false regarding the viability of mammalian sperm, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Sperm Viability**:
- Viability refers to the ability of sperm to survive and maintain functionality, particularly motility, which is crucial for fertilization.

2. **Evaluating the First Statement**:
- The first statement claims that "sperm must be concentrated in a thick suspension."
- **Analysis**: This is true. A thicker suspension enhances sperm motility, which is essential for viability.

3. **Evaluating the Second Statement**:
- The second statement claims that "the sperm is viable for only up to 24 hours."
- **Analysis**: This is false. Mammalian sperm can remain viable for several days, depending on the species and conditions. Therefore, this statement is incorrect.

4. **Evaluating the Third Statement**:
- The third statement claims that "the survival of the sperm depends on pH of the medium and is more active in the alkaline medium."
- **Analysis**: This is true. Sperm viability is indeed influenced by the pH of the medium, with optimal conditions being slightly alkaline (around pH 7.4 to 8.0).

5. **Evaluating the Fourth Statement**:
- The fourth statement claims that "the viability of sperm is determined by its motility."
- **Analysis**: This is true. Sperm motility is a key indicator of its viability; more motile sperm are generally more viable.

6. **Conclusion**:
- After analyzing all statements, the only false statement regarding the viability of mammalian sperm is the second one, which states that sperm is viable for only up to 24 hours.

### Final Answer:
The false statement in respect of the viability of mammalian sperm is: "the sperm is viable for only up to 24 hours."