Question

RR(red) is crossed with rr(white). All Rr offspring are pink. This indicates that ‘R’ gene is

• A. Hybrid
• B. Incompletely dominant
• C. Mutant
• D. Recessive

Answer 1

The correct option is B Incompletely dominant

The above cross is a classical case of incomplete dominance in which heterozygous offspring show an intermediate phenotype.
This can be explained in a quantitative way. To get a red color phenotype product of both the R alleles are needed. Since in the heterozygous condition both alleles show reduced expression, the gene expression is of intermediate level.