If two heterozygous parents (genotype Bb) for brown eye colour have children, what is the probability that an offspring will have blue eyes (bb)?
Answer and explanation
Correct answer: D. 25 percent
- Step 1: Construct a Punnett square for Bb x Bb: BB (25%), Bb (50%), bb (25%). Step 2. The homozygous recessive genotype bb represents 1 out of 4 possible outcomes (25%). Answer: 25 percent. Why not the others: 75% is the probability of the dominant phenotype; 50% is the heterozygous frequency.
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