Which statement about alleles is not true?

A trait that fully manifests itself, in heterozygous condition, is referred to as the dominant trait and the allele controlling it is known as a dominant allele. The trait that does not express itself in heterozygous condition or whose effect is masked by the presence of dominant trait is known as a recessive trait and the responsible allele is termed as a recessive allele. Dominant-recessive relationship of alleles is due to the production of less functional protein/non-functional protein/no protein product at all by a recessive allele.