What is allelic exclusion and why is it important?

Allelic exclusion is defined as a process in which only one allelic gene is expressed and other allele remains silenced.

Allelic exclusion plays important role for cell surface receptors in genes and  in immune cells like B lymphocytes. The allelic exclusion controls binding site of B cells and allows only one type of binding site expressed in each B cell as    binding site of an antibody is decided by the combination of a particular heavy and light chain.

the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".