Question

For Mendel's pea plants, the tall phenotype is determined by a dominant allele and the dwarf phenotype by a recessive allele. Suppose there is a cross between true-breeding tall and true-breeding dwarf plants. What is the expected outcome in the second or F2 generation when F1 plants are crossed to each other?

Answer 1

The expected outcome in the F2 generation when crossing two F1 heterozygous tall pea plants is a phenotypic ratio of 3 tall to 1 dwarf plant and a genotypic ratio of 1 TT: 2 Tt: 1 tt.

Step-by-step explanation:

When crossing true-breeding tall pea plants (homozygous dominant, TT) with true-breeding dwarf plants (homozygous recessive, tt), the F1 generation will consist of only heterozygous tall plants (Tt). Upon crossing these F1 plants with each other, the F2 generation is produced.

The expected outcome, based on Mendelian genetics and depicted in a Punnett square, is a phenotypic ratio of 3:1, where three-quarters of the offspring should be tall and one-quarter dwarf. The resulting genotype ratio would be 1 homozygous dominant (TT): 2 heterozygous (Tt): 1 homozygous recessive (tt).