Question

In Mendel's experiments with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), yellow cotyledon (YY) was dominant over green cotyledon (yy). What are expected phenotypes in F${}_2$ generation of RRYYx rryy?

• A. Only wrinkled seeds with green cotyledons
• B. Only wrinkled seeds with yellow cotyledons
• C. Only round seeds with green cotyledons
• D. Round seeds with yellow cotyledons and wrinkled seeds with green cotyledons

Answer 1

Answer: (D)

Round seeds with yellow cotyledons and wrinkled seeds with green cotyledons

P${}_1$ generation : RRYY x rryy

F${}_1$ generation : RrYy

P${}_2$ generation : RrYy x RrYy

Gametes RrYy ---> RrYy	RY	Ry	rY	ry
RY	RRYY (round, yellow seeds)	RRYy (round, yellow seeds)	RrYY (round, yellow seeds)	RrYY (round, yellow seeds)
Ry	RRYy (round, yellow seeds)	RRyy (round, green seeds)	RrYy (round, yellow seeds)	Rryy (round, green seeds)
rY	RrYY (round, yellow seeds)	RrYy (round, yellow seeds)	rrYY (wrinkled, yellow seeds)	rrYy (wrinkled, yellow seeds)
ry	RrYy (round, yellow seeds)	Rryy (round, green seeds)	rrYy (wrinkled, yellow seeds)	rryy (wrinkled, green seeds)

Phenotypic ratio = 9 (round, yellow seeds) : 3 (round, green seeds) : 3 (wrinkled, yellow seeds) : 1 (wrinkled, green seeds). Thus, option D is correct.