Question

In a random mating population, the frequency of allele A1 and A2 in the gene pool is 0.8 and 0.2, respectively. In a population of 200 plants, how many will have the genotype A1A2?

• A. 8
• B. 128
• C. 64
• D. 32

Hint:

Don't forget the "2" in $2pq$! Heterozygotes come from two combinations (A1 from mom/A2 from dad, or vice versa).

Answer 1

The Correct Option is C

Step 1: Concept
According to the Hardy-Weinberg equilibrium, the frequency of the heterozygous genotype ($2pq$) is calculated using the allele frequencies $p$ and $q$.

Step 2: Meaning
Given $p (A1) = 0.8$ and $q (A2) = 0.2$.

Step 3: Analysis
Frequency of $A1A2 = 2 \times p \times q = 2 \times 0.8 \times 0.2 = 0.32$. To find the number of plants, multiply this frequency by the total population: $0.32 \times 200 = 64$.

Step 4: Conclusion
Exactly 64 plants will have the $A1A2$ genotype. Final Answer: (C)