Response:
The P generation alongside the F1 generation will display only cleft chins.
Each member of the F1 generation will also present with cleft chins.
Explanation:
Within humans, a cleft chin is dominant while no cleft chin is recessive. When two true breeding parents are crossed, the P and F1 generation will consist entirely of cleft chins , however, the F2 generation will have 75% of offspring with cleft chins and 25% with no cleft chin.
Assuming 'A' symbolizes the dominant trait (cleft chin) and 'a' indicates the recessive trait (no cleft chin). The crossing is presented below:
Parental AA x aa
F1 generation Aa Aa Aa Aa
For the F2 generation, the F1 generation offspring that are heterozygotes, i.e., Aa & Aa will interbreed.
F1 generation Aa x Aa
F2 generation AA Aa Aa aa
Even though the offspring in F1 generation are heterozygotes for the trait, phenotypically they will all have cleft chins.