Genetics problem?

Question

a tall pea plant is crossed with a recessive dwarf pea plant. what will the phenotypic and genotypic ratio of offspring be

a. if the tall plant was TT?
b. if the tall plant was Tt?

Answer 1

On the other hand, Punnett is purported to have devised the square trick as a device for explaining genetics to dumb people, so:

All of the offspring from teh dwarf plant will get a recessive allele (t) from it.

If the tall plants are TT then all of the offspring will get a T allele from it so alll of the offspring will be Tt.

It the tall plants are Tt 50% will get T allele from it and be Tt, the other 50% will get t allele from it and be tt .

Answer 2

Just do these on a Punnett square. Use a standard pattern to work out your crosses and you will find these to be very easy.

a. Parents: TT x tt
Gametes from first parent: T and T; place these on the left side of the Punnett square. Gametes from second parent: t and t; place these on the top of the square.

Results in the square:
First row has Tt, Tt
Second row has Tt, Tt
F1: all Tt which means all are tall.

b. If the tall is Tt ...

Parents: Tt x tt
Gametes: T and t on the left of the square; t and t on the top.
Results in the square:
First row is Tt, tt.
Second row is Tt, tt.
F1 1 tall: 1 short