1
Question
In Cucurbita, W is epistatic over Y and y gene, normally responsible for yellow and green colour fruits respectively. It produces white fruits. What is the ratio of fruits in the progeny of cross WwYy x wwYy?
In Cucurbita, W is epistatic over Y and y gene, normally responsible for yellow and green colour fruits respectively. It produces white fruits. What is the ratio of fruits in the progeny of cross WwYy x wwYy?
Open in App
Solution
The correct option is D 4 white : 3 yellow : 1 green
Dominant epistasis is the non-allelic gene interaction where the presence of one dominant gene masks the expression of another dominant gene. According to the question, white colour is dominant over yellow and green while green is recessive to yellow. Thus, the presence of a single copy of the white colour gene produces the effect (W_Y_ and W_yy) and masks the expression of the yellow colour gene. The white colour gene is epistatic to yellow colour gene. The yellow colour is expressed when the recessive copy of an epistatic gene is present with the dominant hypostatic gene (wwY_). The green colour is expressed both genes are present in the recessive form. Thus, a cross between WwYy x wwYy produces 4 white : 3 yellow : 1 green. Thus, the correct answer is C.
Gametes
WwYy ----->
wwYy WY Wy wY wy wY WWYY
(white fruits) WwYy
(white fruits)
wwYY
(yellow fruits)
wwYy
(yellow fruits)
wy WwYy
(white fruits)
Wwyy
(white fruits)
wwYy
(yellow fruits)
wwyy
(green fruits)
Dominant epistasis is the non-allelic gene interaction where the presence of one dominant gene masks the expression of another dominant gene. According to the question, white colour is dominant over yellow and green while green is recessive to yellow. Thus, the presence of a single copy of the white colour gene produces the effect (W_Y_ and W_yy) and masks the expression of the yellow colour gene. The white colour gene is epistatic to yellow colour gene. The yellow colour is expressed when the recessive copy of an epistatic gene is present with the dominant hypostatic gene (wwY_). The green colour is expressed both genes are present in the recessive form. Thus, a cross between WwYy x wwYy produces 4 white : 3 yellow : 1 green. Thus, the correct answer is C.
| Gametes WwYy -----> wwYy | WY | Wy | wY | wy |
| wY | WWYY (white fruits) | WwYy (white fruits) | wwYY (yellow fruits) | wwYy (yellow fruits) |
| wy | WwYy (white fruits) | Wwyy (white fruits) | wwYy (yellow fruits) | wwyy (green fruits) |
Suggest Corrections
0
Similar questions
View More
Join BYJU'S Learning Program
Explore more
Join BYJU'S Learning Program
