Question

A true-breeding plant with green pods and wrinded seeds is crossed with a plant that is heterozygous for both traits. Drawa

Punnett square to predict the outcome of this cross. List the possible genotypes and their phenotypes. (Note: yellowis
dominant to green and round is dominant to wrinkled),

Answer 1

The possible genotype would be when one of the parent is homozygous dominant - Phenotype ratio= 16:0, genotype ratio= 1 YYRR : 1YYRr: 1 yYRR: 1 YyRr.

when one of the parent is homozygous recessive the phenotype ratio is 4 yellow and round : 4 yellow and wrinkle : 4 green and round : 4 green and wrinkle and genotype ratio = YyRr: Yyrr: yyRr: yyrr or

1:1:1:1 genotype ratio.

Step-by-step explanation:

The data given:

yellow and round dominant --- Y R

Green and wrinkle recessive ---- yr

It is given a true breeding plant, which means the parent plant is homozygous for the trait. Let one of the parent be YYRR

Also it is given that it was crossed with heterozygous parent so the other parent be YyRr

The cross between them is shown in punnet square as:

YR Yr yR yr

YR YYRR YYRr yYRR YyRr

YR YYRR YYRr YyRR YyRr

YR YYRR YYRr YyRR YyRr

YR YYRR YYRr YyRR YyRr

4 YYRR: 4 YYRr: 4 YyRR: 4 YyRr

thus genotype ratio is 1:1:1:1

phenotype ratio all 16 are yellow and round.

In case when either parent is homozygous recessive is crossed with heterozygous parent. The punnet square for this is shown as:

yyrr X YyRr

YR Yr yR yr

yr YyRr Yyrr yyRr yyrr

yr YyRr Yyrr yyRr yyrr

yr YyRr Yyrr yyRr yyrr

yr YyRr Yyrr yyRr yyrr

4 YyRr: 4 Yyrr: 4yyRr: 4yyrr

1:1:1:1 genotype ratio

phenotype ratio = 4 yellow and round : 4 yellow and wrinkle : 4 green and round : 4 green and wrinkle.

Thus phenotype ratio is 1:1:1:1