At the end of 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 1: Understand the Cell Cycle
The cell cycle consists of several phases: G1, S, G2, and M. In the G1 phase, the cell grows and prepares for DNA replication. The S phase is where DNA replication occurs, resulting in the duplication of the genetic material.

**Hint:** Remember that the S phase is crucial for DNA replication.

### Step 2: Analyze the G2 Phase
At the end of the G2 phase, the cell has completed DNA replication. This means that the amount of DNA in the cell has doubled compared to the amount present at the end of the G1 phase.

**Hint:** The G2 phase follows the S phase, where DNA replication occurs.

### Step 3: Determine Chromosome Number
In a diploid cell (2n), the chromosome number remains the same throughout the cell cycle, except during the M phase when the chromosomes are separated. Therefore, at the end of the G2 phase, the chromosome number is still 2n.

**Hint:** The chromosome number in a diploid cell is always represented as 2n.

### Step 4: Determine DNA Content
The amount of DNA is represented as 'C'. At the end of the G1 phase, the DNA content is C. After the S phase, the DNA content doubles to 2C. By the end of the G2 phase, the DNA content is further doubled to 4C.

**Hint:** The DNA content doubles during the S phase and remains at that level through the G2 phase.

### Step 5: Conclusion
At the end of the G2 phase, we have:
- Chromosome number: 2n (diploid)
- Amount of DNA: 4C (after replication)

Thus, the correct answer is **2n and 4C**.

### Final Answer
The answer to the question is **Option D: 2n and 4C**.

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