For the MN-blood group system, the frequencies of M and N alleles are 0.7 m and 0.3, respectively . The expected frequency of MN-blood group bearing organisms in likely to be

Options

A. 0.42
B. 0.49
C. 0.09
D. 0.58

Answer

To solve the problem regarding the expected frequency of MN-blood group bearing organisms using the Hardy-Weinberg principle, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Allele Frequencies**:
- Given that the frequency of allele M (p) is 0.7 and the frequency of allele N (q) is 0.3.

2. **Understand the Hardy-Weinberg Equation**:
- The Hardy-Weinberg equation is given by:
\[ p^2 + q^2 + 2pq = 1 \]
- Here, \(p^2\) represents the frequency of homozygous dominant (MM), \(q^2\) represents the frequency of homozygous recessive (NN), and \(2pq\) represents the frequency of heterozygous (MN).

3. **Calculate the Frequency of MN Blood Group**:
- The frequency of the MN blood group (heterozygous) can be calculated using the formula \(2pq\):
\[ 2pq = 2 \times p \times q \]
- Substituting the values of p and q:
\[ 2pq = 2 \times 0.7 \times 0.3 \]

4. **Perform the Calculation**:
- Calculate \(2 \times 0.7 \times 0.3\):
\[ 2 \times 0.7 = 1.4 \]
\[ 1.4 \times 0.3 = 0.42 \]

5. **Interpret the Result**:
- The expected frequency of the MN blood group is 0.42, which can also be expressed as 42%.

### Final Answer:
The expected frequency of MN-blood group bearing organisms is **0.42** or **42%**.