Question

In garden peas, the yellow seed trait is dominant over green seeds. Also, the round seed trait is dominant over the wrinkled-seed trait. These genes are on separate chromosomes. Suppose that two plants that are heterozygous for both traits are crossed and 720 offspring are produced. About how many progeny will be yellow with round seeds

Answer 1

Answer:

405 individuals will be yellow and round seeded.

Explanation:

Available data:

• the yellow seed trait is dominant over green seeds
• round seed trait is dominant over the wrinkled-seed trait
• These genes are on separate chromosomes

Let´s name the seed color genes Y, and the seed shape gene R

• Y is the dominant allele for seed color expressing yellow

• y is the recessive allele for seed color expressing green

• R is the dominant allele for seed shape expressing round

• r is the recessive allele for seed shape expressing wrinkled

Cross: between two plants that are heterozygous for both traits

Parental)       Yy Rr            x       Yy Rr

Gametes) YR   yR   Yr   yr   YR   yR   Yr   yr

Punnet Square)   YR         yR         Yr         yr

                YR     YYRR     YyRR     YYRr    YyRr

                yR      YyRR      yyRR     YyRr     yyRr

                Yr       YYRr      YyRr      YYrr     Yyrr

                yr        YyRr       yyRr      Yyrr      yyrr

F1) 720 individuals

    9/16 yellow and round seeded individuals, Y-R-

    3/16 green and round seeded individuals, yyR-

    3/16 yellow and wrinkle seeded individuals, Y-rr

    1/16 green and wrinkle seeded individuals, yyrr

Note: the "-" symbol in the phenotypes means that there it could be either a dominant or recessive allele.

If 720 is the total number of individuals in the F1, then:

16 possible genotypes ---------- 100% of the progeny -------- 720 individuals

9 yellow and rounded----------- 56.25% ----------------------------405 individuals

3 green and rounded-------------18.75%------------------------------135 individuals

3 yellow and wrinkled-------------18.75%------------------------------135 individuals

1 green and wrinkled--------------6.25%-------------------------------45 individuals