Archive
20th of March 2017
Biology
Q:


1. 1. Heterozygous tall and red flower pea plants were selfed and total 2000 seeds are collected. What is the total number of seeds for both heterozygous traits? 2.In a cross between a pure tall pea plant with green pod and a pure short plant with yellow pod, how many short plant out of 16 would you expect in F2 generation?





Sahil Kumar Sahoo - CBSE - Class X

Monday, March 20, 2017 at 18:05:PM

A:

Hi Sahil,

1. The genotype of the plant heterozygous tall with red flowers is TtRr.

On self-pollination,

Parents: TtRr × TtRr

Gametes: TR, tR, Tr, tr

Progeny:

TR

tR

Tr

tr

TR

TTRR

TtRR

TTRr

TtRr

tR

TtRR

ttRR

TtRr

ttRr

Tr

TTRr

TtRr

TTrr

Ttrr

tr

TtRr

ttRr

Ttrr

ttrr

 So, 25% of the progeny is heterozygous for the trait.

Now, out of 2000 seeds, the number of seeds that are heterozygous for the trait = 25% of 2000 = 500.

Hence, 500 seeds would be heterozygous for the trait.

2. Genotype

Pure tall plant with green pod: TTYY

Pure short plant with yellow pod: ttyy

Gametes: TY, ty

Progeny in F1 generation : TtYy

Self-pollination of F1 generation: TtYy × TtYy

Gametes: TY, tY, Ty, ty

Progeny in F2 generation:

TY

tY

Ty

ty

TY

TTYY

TtYY

TTYy

TtYy

tY

TtYY

ttYY

TTYy

ttYy

Ty

TTYy

TtYy

TTyy

Ttyy

ty

TtYy

ttYy

Ttyy

ttyy

So, out of 16 progeny, 4 progeny would be short.

Monday, March 20, 2017 at 18:36:PM