If haploid chromosome number in an organism is12, what is the chromosome number present in its trisomic ?

Options

A. 11
B. 13
C. 25
D. 23

Answer

To determine the chromosome number present in a trisomic organism when the haploid chromosome number is given as 12, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Haploid Number**: The haploid number (n) is the number of chromosomes in a gamete. In this case, it is given that n = 12.

2. **Calculate the Diploid Number**: The diploid number (2n) is twice the haploid number, representing the total number of chromosomes in somatic (body) cells. Therefore, we calculate:
\[ 2n = 2 \times 12 = 24 \]
So, the diploid number is 24.

3. **Define Trisomy**: Trisomy is a condition where there is an extra copy of one specific chromosome. This means that instead of having two copies of that chromosome, there are three.

4. **Calculate the Chromosome Number in Trisomy**: In a trisomic condition, one chromosome is added to the diploid number. Therefore, we add 1 to the diploid number:
\[ \text{Trisomic chromosome number} = 2n + 1 = 24 + 1 = 25 \]

5. **Final Answer**: The chromosome number present in the trisomic organism is 25.

### Summary:
The chromosome number in a trisomic organism, given a haploid number of 12, is 25.

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