In Codominance, both alleles of a pair express themselves fully in F1 hybrid, so, it resembles both the parents. In incomplete dominance, the two genes of an allelomorphic pair are not related as dominant or recessive but each of them expresses itself partially.

Mendelian Idea Depicted by a Cross in which the F1 Generation Resembles Both Parents: Co-dominance

Co-dominance is the Mendelian idea depicted by a cross in which the F1 generation resembles both parents. In this type of inheritance, both alleles of a gene are fully expressed and contribute equally to the phenotype of the heterozygote.

Explanation:

Co-dominance occurs when both alleles in a heterozygous individual are expressed equally and simultaneously without blending. This means that both alleles are fully visible and neither dominates or masks the other.

Key Points:
- Co-dominance is a form of inheritance where both alleles contribute to the phenotype in an individual.
- Unlike in complete dominance, where one allele is dominant and masks the expression of the other recessive allele, co-dominance allows both alleles to be fully expressed.
- The F1 generation in a cross showing co-dominance will exhibit traits that resemble both parents equally.
- Co-dominance is often observed in blood type inheritance. For example, the ABO blood group system has three alleles: A, B, and O. If an individual inherits an A allele from one parent and a B allele from the other parent, they will have the AB blood type, where both A and B antigens are present on their red blood cells.

Example:

Let's consider a cross between a red-flowered plant (RR) and a white-flowered plant (WW). In this case, the F1 generation will have red and white flowers simultaneously, resulting in pink flowers. This is an example of incomplete dominance, not co-dominance. In incomplete dominance, the heterozygous phenotype is an intermediate between the two homozygous phenotypes.

To illustrate co-dominance, we can consider the ABO blood type system. For example, if a person has one A allele (IA) and one B allele (IB), they will have the AB blood type, where both A and B antigens are expressed on their red blood cells. This demonstrates co-dominance, as both alleles are fully expressed and contribute to the phenotype.