A somatic cell that has just completed the S phase of its cells cycle , as compared the the gamete of the same species ,has :

Options

A. Twice the number of chromosomes and twice the amount of DNA
B. Same number of chromosomes but twice the amount of DNA
C. Twice the number of chromosomes and four times the amount of DNA
D. Four times number of chromosomes and four twice the amount of DNA

Answer

To solve the question regarding the comparison of a somatic cell that has just completed the S phase of its cell cycle with a gamete of the same species, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the S Phase**:
- The S phase (Synthesis phase) of the cell cycle is when DNA replication occurs. This means that the amount of DNA in the cell doubles, but the number of chromosomes remains the same at this point.

2. **Chromosome and DNA Content in Somatic Cells**:
- Let's denote the normal diploid somatic cell as having 2N chromosomes and 2C amount of DNA (where N is the haploid number of chromosomes and C is the amount of DNA).
- After the S phase, the somatic cell will still have 2N chromosomes (since the number of chromosomes does not change until mitosis) but will have 4C amount of DNA (because the DNA has been replicated).

3. **Understanding Gametes**:
- Gametes are haploid cells, meaning they have half the number of chromosomes compared to diploid somatic cells. Therefore, a gamete will have N chromosomes and C amount of DNA.

4. **Comparing the Somatic Cell and Gamete**:
- After the S phase, the somatic cell has:
- Chromosomes: 2N (same as before S phase)
- DNA: 4C (double the amount of DNA compared to the original somatic cell)
- The gamete has:
- Chromosomes: N
- DNA: C

5. **Final Comparison**:
- When comparing the somatic cell after the S phase (2N chromosomes and 4C DNA) with the gamete (N chromosomes and C DNA):
- The number of chromosomes in the somatic cell is twice that of the gamete (2N vs. N).
- The amount of DNA in the somatic cell is four times that of the gamete (4C vs. C).

6. **Conclusion**:
- Therefore, the correct answer is that the somatic cell that has just completed the S phase has twice the number of chromosomes and four times the amount of DNA compared to the gamete of the same species.

### Answer:
C) Twice the number of chromosomes and four times the amount of DNA.

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