a homozygous tall pea plant with green seeds is crossed with a dwarf plant with yellow seeds

a) what would be the phenotype and genotype of F1?

b) work out the phenotypic ratio of F1 generation with the help of peanutt square .

Parents                            TTyy                   x                      ttYY
                                         
Gametes                          Ty                                             tY
​ 
F1                                                           TtYy      (all plants are tall and yellow)
                                                             selfing​
                           

Gametes
        f₂ generation      

a) All the plants in f₁ generation are tall plants with yellow seeds having genotype TtYy

​b) Second part of your question seems to be wrong, ii might be Phenotypic ratio of f₂ generation.​
The phenotypic ratio in F₂ generation would be 

Tall yellow : Tall green : Dwarf yellow : Dwarf green
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