Question

In garden pea, yellow colour of cotyledon (Y) is dominant over green colour (y) and round seed shape (R) is dominant over wrinkle (r). A heterozygous yellow round seeded plants for both the traits is self-pollinated, then the ratio of yellow wrinkle would be

• A. 9/16
• B. 1/16
• C. 3/16
• D. 1/4

Answer 1

Answer: (C)

Given :

Y (yellow) is dominant over green (y) colour and round (R) is dominant over wrinkle (r).

YyRr is self pollinated. Therefore, the cross will be YyRr x YyRr

Gametes formed will be : Yr. Yr, yR, yr and Yr. Yr, yR, yr

F${}_1$ generation will consists of : YYRR, YYRr, YyRR, YyRr, YYrR, YYrr, YyrR, Yyrr, YYRR, yYRr, yyRR, yyRr, yYrR, yYrr, yyrR, yyrr.

Therefore, 9 will show the Y and R phenotypes.

3 will show the Y and rr phenotypes.

3 will show the yy and R phenotypes.

1 will show the yyrr phenotype.

Genotype of yellow wrinkle seeds will be Y_rr. Therefore YYrr, Yyrr, Yyrr shows yellow wrinkled seeds. Hence, the ratio is 3/16.