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

Options

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

Explanation

To find the expected frequency of MN blood group bearing organisms in the MN blood group system, we can use the Hardy-Weinberg principle. Here’s a step-by-step solution:

### Step 1: Understand the Allele Frequencies
We are given the frequencies of the M and N alleles:
- Frequency of M (p) = 0.7
- Frequency of N (q) = 0.3

### Step 2: Identify the Genotype Frequencies
According to the Hardy-Weinberg principle, the expected frequencies of the genotypes in a population can be calculated using the formula:
\[ p^2 + 2pq + q^2 = 1 \]
Where:
- \( p^2 \) = frequency of homozygous MM
- \( 2pq \) = frequency of heterozygous MN
- \( q^2 \) = frequency of homozygous NN

### Step 3: Calculate Each Genotype Frequency
1. **Calculate \( p^2 \)** (frequency of MM):
\[ p^2 = (0.7)^2 = 0.49 \]

2. **Calculate \( q^2 \)** (frequency of NN):
\[ q^2 = (0.3)^2 = 0.09 \]

3. **Calculate \( 2pq \)** (frequency of MN):
\[ 2pq = 2 \times (0.7) \times (0.3) = 2 \times 0.21 = 0.42 \]

### Step 4: Summarize the Frequencies
Now we have:
- Frequency of MM = \( p^2 = 0.49 \)
- Frequency of NN = \( q^2 = 0.09 \)
- Frequency of MN = \( 2pq = 0.42 \)

### Step 5: Conclusion
The expected frequency of MN blood group bearing organisms is 0.42 or 42%.

### Final Answer
Thus, the expected frequency of MN blood group bearing organisms is **42%**.

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