How many chromosomes will the diploid cell have at G.. after S and after M - phase respectively if the haploid cell has 7 chromosomes ?

Options

A. 7,7,14
B. 7,14,14
C. 14,14,14
D. 7,7,7

Answer

To solve the question regarding the number of chromosomes in a diploid cell at different phases of the cell cycle, we start with the information provided about haploid cells.

### Step-by-Step Solution:

1. **Understanding Haploid and Diploid Cells**:
- A haploid cell contains one complete set of chromosomes. According to the question, the haploid cell has 7 chromosomes.
- A diploid cell contains two complete sets of chromosomes. Therefore, the number of chromosomes in a diploid cell can be calculated as:
\[ \text{Diploid chromosomes} = 2 \times \text{Haploid chromosomes} = 2 \times 7 = 14 \]

2. **Chromosome Count at G1 Phase**:
- At the G1 phase (the first gap phase), the diploid cell will have the same number of chromosomes as it does in its resting state, which is 14 chromosomes.

3. **Chromosome Count After S Phase**:
- During the S phase (synthesis phase), DNA replication occurs. Each chromosome is replicated, resulting in two sister chromatids for each chromosome. However, the total number of chromosomes remains the same because they are still counted as a single chromosome. Therefore, after the S phase, the diploid cell still has:
\[ \text{Chromosomes after S phase} = 14 \]

4. **Chromosome Count After M Phase**:
- During the M phase (mitosis), the sister chromatids are separated into two daughter cells. Each daughter cell will receive one copy of each chromosome. Therefore, after the M phase, the diploid cell will still have:
\[ \text{Chromosomes after M phase} = 14 \]

### Summary of Chromosome Counts:
- At G1 phase: 14 chromosomes
- After S phase: 14 chromosomes
- After M phase: 14 chromosomes

### Final Answer:
The diploid cell will have 14 chromosomes at G1, 14 after S phase, and 14 after M phase respectively.