(a) How are polygenic inheritance and multiple allelism different ? Explain with the help of an example each.
(b) List the criteria a chemical molecule must fulfill to be able to act as a genetic material.

Explanation

(a) Polygenic inheritance : The polygenic of quantitative inheritance in which complete expression of controlled by two or more gene. For example , : Two pairs of unit factors e.g. seed colour of wheat
`{:(,,R_(1)R_(1)R_(2)R_(2)xxr_(1)r_(1)r_(2)r_(2),),(F_(2)" phenotype",," "1:4:6:4:1,),("ratio",," (5 phenotypes)",):}`
Three pairs of unit factors e.g. skin colour of human
`{:(,,"AA BB CC"xx"aa bb cc",),(F_(2)" phenotype",," "1:6:15:20:15:6:1,),("ratio",," (7 phenotypes)",):}`
Multiple alleliem : These are genes which have more than two alleles forms control a particular character. The alleles occurs at some gene locus distributed in different organisms.Each organism carries only two alleles and in the gametes only single alleles is present. e.g. ABO blood group of human controlled by s single gene which has three alleles is present. e.g.
(b) `*` It should be able to genertae its replica (replication).
`*` It should chemically and structurally be stable.
`*` It should provide the scope for slow change (mutation) that are required fro evolution.
`*` It should be able to express itself in the form of 'Mendelian characters'.