Question

in humans, the gene for polydactyly (having extra fingers or toes) is dominant over the gene for the normal number of digits. if parents who are both homozygous dominant for polydactyly have four children, how many of these children would most likely have extra fingers or toes?
0
2
3
4

Explanation:

1. Let the dominant allele for polydactyly be \( P \) and the recessive (normal) allele be \( p \).
2. Both parents are homozygous dominant, so their genotypes are \( PP \).
3. When they produce gametes, each parent can only contribute \( P \) (since they are \( PP \)).
4. The offspring's genotype will be \( PP \) (from \( P \) of father and \( P \) of mother).
5. Since the allele for polydactyly (\( P \)) is dominant, all offspring with \( PP \) genotype will express the polydactyly trait.
6. If there are four children, all four (100% of the offspring in this cross) are expected to have extra fingers/toes.

Answer:

4 (the option with "4")