Question
Biology Question on Principles of Inheritance and Variation
RR (Red) Antirrhinum is crossed with white (WW) one. Offspring RW are pink. This is an example of
A
dominant-recessive
B
incomplete dominance
C
hybrid
D
supplementary genes.
Answer
incomplete dominance
Explanation
Solution
The inheritance of flower colour in the dog flower (snapdragon or Antirrhinum sp.) is a good example which shows incomplete dominance. In a cross between true-breeding red-flowered (RR) and true- breeding white-flowered plants (rr), the F (Rr) was pink. When the F was self-pollinated the F resulted in the following ratio, 1 (RR) Red : 2 (Rr) Pink : 1 (rr) White. Here the genotype ratios were 1 : 2 : 1 as in any Mendelian monohybrid cross, but the phenotype ratios had changed from the 3 : 1 dominant: recessive ratio to 1:2: 1.