Principles of Inheritance and Variation Question 47
47. In Mendel’s experiment with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), yellow cotyledon (YY) was dominant over green cotyledon (yy). What are the expected phenotypes in the $F_2$ generation of the cross RRYY $\times$ rryy?
[2006]
(a) only wrinkled seeds with yellow cotyledons
(b) only wrinkled seeds with green cotyledons
(c) Round seeds with yellow cotyledons, and wrinkled seeds with yellow cotyledons
(d) only round seeds with green cotyledons
Show Answer
Answer : c
Hints & Solution
(c)
| RY | Ry | $rY$ | ry | |
|---|---|---|---|---|
| R | RRYY Round seed yellow coty. |
RRYy Round seed yellow coty. |
RrYY Round seed yellow coty. |
RrYy Round seed yellow coty. |
| RRYy Round seed yellow coty. |
RRyy Round green $c$ |
$RrYy$ Round s yellow c |
Rry Round green |
|
| $rY$ | RrYY Round seed yellow coty. |
RrYy Round seed yellow coty. |
rrYY Wrinkled seed yellow coty. |
rrYy Wrinkled seed yellow coty. |
| ry | RrYy Round seed yellow coty. |
Rryy Round seed green coty. |
rrYy Wrinkled seed yellow coty. |
rryy Wrinkled seed green coty. |
| So the ratio of Round seeded with yellow cotyledons : Round seeded green cotyledons : Wrinkled seeded yellow cotyledons : Wrinkled seeded green cotyledons is $9: 3: 3: 1$. So in | ||||
| the $F_2$ generation, the round seeded character remains with yellow cotyledons & wrinkled seeds with yellow cotyledons. |
