When one parent is homozygous dominant for free earlobes and the other has attached earlobes, all children will have free earlobes. A Punnett square activity demonstrates that all offspring will inherit the dominant 'F' allele, resulting in free earlobes and making attached earlobes an impossible outcome.
In human genetics, if one parent is homozygous dominant for free earlobes (FF) and the other parent has attached earlobes (ff), their children cannot have attached earlobes. To visualize this, we can use a Punnett square. The dominant parent contributes an 'F' allele to all offspring, while the recessive parent contributes an 'f' allele. Therefore, all children will have the genotype 'Ff' and exhibit the dominant trait of free earlobes.
A Punnett square would display the crossing of 'FF' (homozygous dominant) and 'ff' (homozygous recessive) as follows:
- Column 1: F from dominant parent
- Column 2: F from dominant parent
- Row 1: f from recessive parent
- Row 2: f from recessive parent
All four resulting squares would have 'Ff', showing that 100% of the children will have free earlobes.
It is genetically impossible for these parents to produce children with attached earlobes as the dominant free earlobe allele will always express itself in the presence of the recessive allele for attached earlobes.