In a monohybrid cross of plants with red and white flowered plants, Mendel got only red flowered plants. On self-pollinating these F1 plants got both red and white flowered plants in 3:1 ratio. Explain the basis of using RR and rr symbols to represent the genotype of plants of parental generation.

Question

In a monohybrid cross of plants with red and white flowered plants, Mendel got only red flowered plants. On self-pollinating these F1 plants got both red and white flowered plants in 3:1 ratio. Explain the basis of using RR and rr symbols to represent the genotype of plants of parental generation.

Philoid · Accepted Answer

On crossing red (RR) and white(rr) flowered plants, Mendel got only red flowered plants with genotype Rr. This is the filial progeny (F₁) or plants of the 1st hybrid generation. F₁ always resembled either one of the parents and the trait of other parent was not seen in them.

Now on self-pollinating these F �₁ plants (that is Rr x Rr) he got some of the offspring’s of Filial₂ generation to be white; which was not seen in F₁ was now expressed. The red and white traits were identical to their parental type and did not show any blending (none was of pink colour). F₂ stage , both the traits were expressed in the proportion 3:1.