The allele represented by a capital letter

The allele represented by a lowercase letter

When both alleles in the genotype are the same

When the two alleles in the genotype are different from one another

The allele that is only expressed when there are two copies present

The allele that is expressed when one or two copies are present

TT

tt

Tt

The area colored red in the image:

The area colored yellow in the image:

The P (parental) genotypes in the cross shown:

The allele for a straight thumb (S) is dominant over a hitchhiker's thumb (s). Which phenotype will a person display if their genotype is Ss?

The allele for a straight thumb (S) is dominant over a hitchhiker's thumb (s). Which phenotype will a person display if their genotype is ss?