Calculating Heterozygote Frequency
If gene frequency of $A = 0.7$ & $a = 0.3$, find out genotypic frequency of heterozygote:
- 0.42 — Correct Answer
- 0.21
- 0.49
- 0.09
Explanation:
Correct Answer: 0.42
Under Hardy-Weinberg equilibrium, genotypic frequencies are calculated from gene frequencies as: p² (AA) + 2pq (Aa) + q² (aa) = 1.
Step-by-Step Calculation
- Given: p (frequency of A) = 0.7; q (frequency of a) = 0.3
- Check: p + q = 0.7 + 0.3 = 1.0 ✓
- Frequency of heterozygote (Aa) = 2pq = 2 × 0.7 × 0.3 = 0.42
All Genotypic Frequencies for This Example
| Genotype | Formula | Frequency |
|---|---|---|
| AA (homozygous dominant) | p² = (0.7)² | 0.49 |
| Aa (heterozygous) | 2pq = 2 × 0.7 × 0.3 | 0.42 |
| aa (homozygous recessive) | q² = (0.3)² | 0.09 |
| Total | p² + 2pq + q² | 1.00 |
Important Note
- Frequency of heterozygotes (2pq) can never exceed 50% and is maximum when p = q = 0.5 → 2pq = 0.50
📚 About this Topic — Animal Genetics & Breeding
This multiple choice question is from Animal Genetics & Breeding, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Genetics & Breeding to strengthen your preparation.
