At the end the `G_2` phase , the number of chromosomes and the amount of DNA in a diploid cell , respectively , is

Options

A. n and 2C
B. 2n and C
C. n and 4C
D. 2n and 4C

Answer

To solve the question regarding the number of chromosomes and the amount of DNA in a diploid cell at the end of the G2 phase, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Diploid Cells**:
- A diploid cell contains two sets of chromosomes, denoted as \(2n\). For example, in humans, \(n = 23\), so a diploid cell has \(2n = 46\) chromosomes.

2. **Phases of the Cell Cycle**:
- The cell cycle consists of interphase (which includes G1, S, and G2 phases) and the M phase (mitosis or meiosis).
- During interphase, the cell prepares for division.

3. **S Phase**:
- During the S phase of interphase, DNA replication occurs. This means that while the number of chromosomes remains the same, the amount of DNA doubles.
- Initially, the amount of DNA in a diploid cell is represented as \(2C\) (where \(C\) is the amount of DNA in a haploid cell).

4. **Transition to G2 Phase**:
- After the S phase, the cell enters the G2 phase. At this point:
- The number of chromosomes is still \(2n\) (as they have not yet divided).
- The amount of DNA has doubled to \(4C\) (because each chromosome now consists of two sister chromatids).

5. **Conclusion**:
- Therefore, at the end of the G2 phase, the number of chromosomes in a diploid cell is \(2n\) and the amount of DNA is \(4C\).

### Final Answer:
The number of chromosomes and the amount of DNA in a diploid cell at the end of the G2 phase is **2N and 4C** (Option D).

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