(a) In a monohybrid cross between tall pea plants denoted by TT and short pea plants denoted by tt, Preeti obtained only tall plants denoted by Tt in the $F_{1}$ generation. However, in $F_{2}$ generation she obtained both tall and short plants. Using the above information explain the Law of dominance.
(b) What is genetic drift ?
(a) According to the law of dominance trait that is dominant gets expressed in the $F_{1}$ generation although both the dominant and the recessive traits get inherited in the $F_{1}$ generation it is only the dominant trait which gets expressed, i.e., a single copy of dominant trait is enough for expression of the tall trait. Traits like T are thus called dominant traits.
(b) Accidents in small population can change the frequency of some genes in a population although they give no survival advantage. This is called genetic drift.