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

Options

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

Answer

To determine which statement is false regarding the viability of mammalian sperm, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Viability of Sperm**:
- Viability refers to the ability of sperm to survive and remain functional for fertilization.

2. **Analyzing the Statements**:
- **Statement 1**: "Sperm is viable only up to 24 hours."
- This statement is false. Mammalian sperm can remain viable for 48 to 72 hours under optimal conditions, not just 24 hours.

- **Statement 2**: "Survival of sperm depends on the pH of the medium and is more active in alkaline medium."
- This statement is true. Sperm survival is indeed influenced by the pH of the medium, and they are more active in alkaline conditions, such as those found in seminal fluid.

- **Statement 3**: "Viability of the sperm is determined by its motility."
- This statement is also true. The motility of sperm is a key factor in determining their viability, as motile sperm are more likely to reach and fertilize the ovum.

- **Statement 4**: "Sperm must be concentrated in a thick suspension."
- This statement is somewhat true. While sperm are typically found in a concentrated form in semen, the concentration does not directly determine their viability.

3. **Identifying the False Statement**:
- After analyzing all the statements, we conclude that the first statement, "Sperm is viable only up to 24 hours," is false because mammalian sperm can survive for a longer duration, typically up to 48 to 72 hours.

### Final Answer:
The false statement regarding the viability of mammalian sperm is: **"Sperm is viable only up to 24 hours."**

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