Definitions / Explanation : Punnett square
Punnett square is a graphical representation to calculate the probability of all possible genotypes of offspring in a genetic cross.
Mendel law is still true because
The first law of Mendel
If a cross is made between $AA$ and $aa$, the nature of ${F_1}$ progeny will be
Punnet square is a representation to calculate
Organism of pure line is that which produce individuals of