Explain Mendel's Monohybrid cross. Give an example.
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Solution
A cross between pure breeding tall (TT) and dwarf (tt) varieties gives all heterozygous tall (Tt) progeny in F1 generation. Selfing of F1hybrid gives tall and dwarf F2 progeny in 3: 1 ratio respectively. Since allele for tallness (T) is dominant over that of dwarfism (t); heterozygous dominant genotype (Tt) gives "tall" phenotype and dwarfism is masked from being expressed. Both homozygous dominant (TT) and heterozygous dominant (Tt) exhibit "tall" phenotype while homozygous recessive genotype gives dwarf phenotype; hence phenotypic ratio is 3 tall: 1 dwarf but the genotypic ratio is 1 TT: 2 Tt: 1 tt.