Question

What is the phenotypic ratio of progeny, when a hetrozygous plant with dominant red flowers is crossed with a homozygous plant with recessive white flowers?

• A. 3 : 1
• B. 1 : 1
• C. 1 : 2 : 1
• D. 9 : 3 : 3 : 1

Answer 1

The correct option is B

1 : 1

The allele for a red flower is R (being the dominant allele) and that for a white flower is r. The cross is between a heterozygous red-flowered plant (Rr) and a white-flowered plant (rr). The following Punnett square shows the combinations obtained from this cross.


The offspring are in the ratio of 2 red-flowered plants to 2 white-flowered plants, which when simplified, is 1:1.