Question

In Cucurbita, W is epistatic over Y and y gene normally responsible for yellow and green colour fruits. It produces white flowers. What is the ratio of fruits in the progeny of cross WwYy $\times$ wwYy?

• A. 9 white : 7 yellow : 0 green
• B. 3 white : 4 yellow : 1 green
• C. 4 white : 3 yellow : 1 green
• D. 2 white : 1 yellow : 1 green

Answer 1

The correct option is C 4 white : 3 yellow : 1 green

In Cucurbita, there are three types of fruit colours – yellow, green and white.

White colour is dominant over other colours, while yellow is dominant over green. The gene for white colour(W) masks the effect of yellow colour gene(Y). So yellow colour is formed only when the dominant epistatic gene is represented by its recessive allele(w). When the hypostatic gene is also recessive(y), the colour of the fruit is green. Genotype of white fruit WWYy,

Genotype of yellow fruit – wwYy, green fruit wwyy.

When a cross is made between WwYy, wwYy, in the next generation 8 progeny are white 6 are yellow and 2 are green. The ratio is 4:3:1

So, the correct option is '4white : 3 yellow : 1 green'.