The number of chromosomes in the shoot tip cells of a maize plant is 20. The number of chromosomes in the microspore mother cells of the same plant shall be

Options

A. 20
B. 10
C. 40
D. 15

Answer

To solve the problem regarding the number of chromosomes in the microspore mother cells of a maize plant, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Chromosome Number in Maize**:
- The question states that the number of chromosomes in the shoot tip cells of a maize plant is 20. This indicates that maize is a diploid organism (2N), meaning it has two sets of chromosomes.

2. **Identify the Type of Cells**:
- The microspore mother cells (MMC) are involved in the formation of male gametes (pollen grains) in flowering plants. These cells are also diploid.

3. **Determine the Chromosome Number in Microspore Mother Cells**:
- Since the microspore mother cells are part of the reproductive structure and are diploid, they will have the same chromosome number as the somatic cells (shoot tip cells). Therefore, the number of chromosomes in the microspore mother cells is also 20 (2N = 20).

4. **Understand the Process of Gamete Formation**:
- The microspore mother cells undergo meiosis to produce microspores, which are haploid (N). During this process, the chromosome number is halved.

5. **Calculate the Haploid Number**:
- Since the diploid number (2N) is 20, the haploid number (N) will be half of that. Thus, N = 20/2 = 10.

6. **Final Answer**:
- The number of chromosomes in the microspore mother cells of the maize plant is 20, and the number of chromosomes in the resulting male gametes will be 10.

### Conclusion:
- The number of chromosomes in the microspore mother cells of the maize plant is **20**.