Topic: Deviations: incomplete dominance, co-dominance, multiple alleles, blood groups, pleiotropy, polygenic inheritance· Genetics and Evolution
The phenomenon of pleiotropism refers to
1. more than two genes affecting a single character.
2. presence of several alleles of a single gene controlling a single crossover.
3. presence of two alleles, each of the two genes controlling a single trait.
4. a single gene affecting multiple phenotypic expression.