Answer:
Dwarf plants should be 20
Tall plants should be 60
Explanation:
This question involves a single gene coding for height in pea plants. The tall allele (T) is dominant over the allele (t). This means that T will always mask the expression of t in a heterozygous state.
Heterozygous state implies a plant that contains both dominant and recessive alleles i.e. Tt. Using a punnet square, two heterozygous pea plants (Tt × Tt) will produce four possible offsprings with genotypes: TT, Tt, Tt and tt.
TT, Tt, Tt are all phenotypically tall while the are phenotypically dwarf. Hence, a 3 Tall : 1 dwarf ratio was obtained. The phenotypic ratio can be used to determine the amount expected in offsprings.
Out of 80 offsprings, 1/4 × 80 will be dwarf i.e. 20
Out of same 80 offsprings, 3/4 × 80 = 60 will be produced.