Which one of the following statements is incorrect?

Alleles are two alternative forms of the same gene. They are present at the same locus on a chromosome. These are heritable. In an offspring, one allele is inherited from father and the other one is inherited from mother. They code for different isoforms of a protein. They are either dominant or recessive. Dominant allele produces dominant phenotype and requires only one copy to express itself. Recessive allele requires two copies to express itself.