Practice question

Monohybrid back cross with dominant parent TT mated to F1 Tt allows dominant parent to contribute only T gametes, F1 generates T and t gametes equally. Fertilisation yields genotypes TT and Tt in 1:1 proportion, both bearing at least one dominant allele T. Because T shows complete dominance over t, all progeny display dominant phenotype such as tall, no recessive phenotype expressed. Recessive appearance requires tt genotype impossible with TT parent, 3:1 appears in selfing, 1:1 ratio occurs only when back crossed to recessive tester.