In a Mendelian dihybrid cross if the individuals with all the four kinds of alleles are 30 in `F_(2)` generation, filnd out thetotal number of `F_(2)` individuals

Options

A. 120
B. 300
C. 240
D. 1600

Answer

To solve the problem of finding the total number of F2 individuals in a Mendelian dihybrid cross when given that there are 30 individuals with all four kinds of alleles, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Dihybrid Cross**: In a dihybrid cross, we are dealing with two traits, each represented by two alleles. For example, let's consider traits such as seed shape (round vs. wrinkled) and seed color (yellow vs. green).

2. **Identify the Genotypes**: In a typical dihybrid cross, the possible combinations of alleles can be represented as:
- Round Yellow (RRYY)
- Round Green (RRYy)
- Wrinkled Yellow (rrYY)
- Wrinkled Green (rrYy)
- And so on, leading to a total of 16 different combinations in the F2 generation.

3. **Given Information**: The problem states that there are 30 individuals with all four kinds of alleles. This means we are focusing on the individuals that exhibit all combinations of the two traits.

4. **Calculate Total F2 Individuals**: In a dihybrid cross, the ratio of phenotypes is typically 9:3:3:1. However, since we are given that there are 30 individuals with all four kinds of alleles, we can infer that these represent one of the combinations.

Since there are 4 combinations of alleles (each representing a different phenotype), we can calculate the total number of F2 individuals by multiplying the number of individuals with all four kinds of alleles by the number of combinations:
\[ \text{Total F2 individuals} = 30 \times 4 = 120 \]

5. **Final Answer**: Therefore, the total number of F2 individuals is 120.