In a classic mendelian monohybrid cross between a homozygous dominant parent and a homozygous recessive parent, which generation is always completely heterozygous

T - dominant allele

t - recessive allele

parental cross: homozygous dominant parent (TT) and a homozygous recessive parent (tt)

The parental cross is true-breeding, so: TTx tt

The F1 generation will be all heterozygote: Tt

Answer: The F1 generation will be 100% heterozygote