Inheritance of one gene can be studied by hybridisation experiment carried out by Mendel where he crossed tall and dwarf pea plants to study the inheritance of one gene.

He collected the seeds produced as a result of this cross and grew them to generate plants of the first hybrid generation.

This generation is also called the filial $_{1}$ progeny or the $\mathrm{F}_{1}$.

– Mendel observed that all the $F_{1}$ progeny plants were tall like one of its parents, none were dwarf. – He made similar observations for the other pairs of traits – he found that the $\mathrm{F}_{1}$ always resembled either one of the parents and that the trait of the other parent was not seen in them.

Mendel then self – pollinated the tall $\mathrm{F}_{1}$ plants and to his surprise found that in the filial $_{2}$ generation some of the offspring were dwarf the character that was not seen in the $\mathrm{F}_{1}$ generation was now expressed.

The proportion of plants that were dwarf were $1 / 4^{\text {th }}$ of the $\mathrm{F}_{2}$ plants while $3 / 4^{\text {th }}$ of the $\mathrm{F}_{2}$ plants were tall.

$=$ The tall and dwarf traits were identical to their parental type and did not show any blending that is all the offspring were either tall or dwarf none were of in between height.