Question

unattached earlobes is a dominant trait, e. a parent who is homozygous for unattached earlobes is crossed with a parent who is homozygous for attached earlobes. which describes the genotypes of their offspring?
100 percent ee
100 percent unattached earlobes
100 percent ee
100 percent attached earlobes

Explanation:

Step1: Determine Parent Genotypes

Homozygous dominant (unattached) parent: \( EE \) (since dominant trait is \( E \)). Homozygous recessive (attached) parent: \( ee \) (recessive trait is \( e \), as attached is recessive to unattached).

Step2: Perform Punnett Square

The \( EE \) parent can only produce \( E \) gametes. The \( ee \) parent can only produce \( e \) gametes. When we cross them, all offspring will get one \( E \) from the first parent and one \( e \) from the second parent, so genotype \( Ee \) for all offspring.

Step3: Analyze Options

• "100 percent unattached earlobes" describes phenotype, not genotype.
• "100 percent ee" is incorrect (offspring get \( E \) from dominant parent).
• "100 percent attached earlobes" is incorrect (attached is recessive, offspring have \( E \) allele so show dominant trait).
• "100 percent Ee" is correct genotype.

Answer:

100 percent Ee