Explain low of Multiple Alleles / Dominance and law of segregation.

 Law of Dominance

$(i)$   Characters are controlled by discrete units called factors.
$(ii)$  Factors occur in pairs.
$(iii)$   In a dissimilar pair of factors one member of the pair dominates
(dominant) the other (recessive).
          The law of dominance is used to explain the expression of only one of the parental characters in a monohybrid cross in the $F_1$ and the expression of both in the $F_2$. It also explains the proportion of $3:1$ obtained at the $F_2$.

  Law of Segregation

This law is based on the fact that the alleles do not show any blending and that both the characters are recovered as such in the $F_2$ generation though one of these is not seen at the $F_1$ stage.

Though the parents contain two alleles during gamete formation, the factors or alleles of a pair segregate from each other such that a gamete receives only one of the two factors. Of course, a homozygous parent produces all gametes that are similar while a heterozygous one produces two kinds of gametes each having one allele with equal proportion.