AaBb individual produces 2 million gametes. How many of them would carry both the recessive alleles (ab)

Options

A. 1.5 million
B. 1.0 million
C. 0.5 million
D. 0.25 million

Answer

To solve the problem of how many gametes produced by an AaBb individual carry both recessive alleles (ab), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotype**: The individual has the genotype AaBb. This means it has one dominant and one recessive allele for both traits.

2. **Determine Gamete Formation**: When an individual with the genotype AaBb produces gametes, it can produce four different types of gametes due to the combinations of alleles:
- AB (dominant A and dominant B)
- Ab (dominant A and recessive b)
- aB (recessive a and dominant B)
- ab (recessive a and recessive b)

3. **Calculate the Proportion of Each Gamete Type**: Since there are four types of gametes, and they are produced in equal proportions, each type will represent 1/4 of the total gametes produced.

4. **Total Gametes Produced**: The individual produces a total of 2 million gametes.

5. **Calculate the Number of Gametes Carrying Both Recessive Alleles (ab)**:
- The proportion of gametes that are of type ab is 1/4.
- Therefore, the number of ab gametes = (1/4) * 2,000,000 = 500,000.

6. **Final Answer**: The number of gametes that carry both recessive alleles (ab) is 500,000, or 0.5 million.