question_answer

In Mirabilis a hybrid for red (RR) and white (rr) flower produces pink (Rr) flower. A plant with pink flower is crossed with white flower the expected phenotypic ratio is:

A)  red: pink : white (1 : 2:1)

B)  pink: white : (1 : 1)

C)  red: pink (1:1)

D)  red: pink (3:1)

Correct Answer: B

Solution :

 Mirabilis jalapa shows incomplete dominance. When the \[{{\text{F}}_{\text{1}}}\]hybrid is crossed with pure recessive parent the cross is called test cross, and it gives 1:1 phenotypic ratio. Hence, the ratio of pink and white flowers is 1:1