Experiments of Monohybrid Cross in Guineapig: For the experiment of monohybrid cross in Guineapig, a homozygous black Guineapig (BB) is crossed with a homozygous white Guineapig (bb), then all hybrids of the first filial generation (Fx) are found to be black (Bb). From this, it is proved that black is dominant over white. As black is pure homozygous and dominant, its genotype will be BB and as white is pure homozygous but recessive, its genotype will be bb. BB will produce one type of gamete B. In F1 the genotype will be Bb. The black hybrid of Fj when mated among themselves produces black and white offspring in 3 : 1 ratio i.e., 75% black and 25% white. Out of 75% black Guineapig 25% are pure black (BB), 50% are hybrid (heterozygous) black (Bb), and 25% are pure white (bb). So, the genotypic ratio becomes 1:2:1.
