If one parent has genotype RR for tongue-rolling and the other rr, what is the phenotype of all offspring regarding tongue-rolling?

If one parent has genotype RR for tongue-rolling and the other rr, what is the phenotype of all offspring regarding tongue-rolling?

• A. Can roll his tongue
• B. Cannot roll his tongue
• C. Some can roll his tongue
• D. Not enough information

Answer: (A)

Rolling tongue is a dominant trait. The allele for rolling (R) masks the recessive allele (r). When a homozygous dominant parent (RR) mates with a homozygous recessive parent (rr), every offspring inherits one R and one r, giving them the genotype Rr. Since the dominant R is present, all offspring express the rolling phenotype. So the best answer is that all offspring can roll their tongues.

Rolling tongue is a dominant trait. The allele for rolling (R) masks the recessive allele (r). When a homozygous dominant parent (RR) mates with a homozygous recessive parent (rr), every offspring inherits one R and one r, giving them the genotype Rr. Since the dominant R is present, all offspring express the rolling phenotype. So the best answer is that all offspring can roll their tongues.