Question

how is codominant inheritance different from incomplete dominant inheritance?
○ in codominance, two alleles are expressed equally; in incomplete dominance, heterozygotes have an intermediate
phenotype.
○ in codominance, the two alleles cooperate to make an intermediate phenotype; in incomplete dominance, the
heterozygote shows the recessive phenotype.
○ in codominance, one gene is recessive to two dominant genes; in incomplete dominance, all genes are recessive.
○ in codominance, two alleles are expressed equally; in incomplete dominance, there is only one allele in the system.
○ in codominance, all genes are recessive; in incomplete dominance, one gene is recessive to two dominant genes.

Explanation:

• Codominance: Both alleles in a heterozygous genotype are fully expressed. For example, in some flower species, if one allele codes for red petals and another for white petals, a codominant inheritance pattern would result in flowers with both red and white patches (like a roan coat in cattle where both red and white hair - color alleles are expressed).
• Incomplete dominance: The heterozygous phenotype is an intermediate between the two homozygous phenotypes. Using the flower example again, if there was incomplete dominance, a heterozygote would have pink petals (an intermediate between red and white).

Let's analyze the other options:

• Option 2: In codominance, there is no intermediate phenotype made by allele cooperation. And in incomplete dominance, the heterozygote does not show the recessive phenotype.
• Option 3: In codominance, there is no situation of one gene being recessive to two dominant genes. Also, in incomplete dominance, genes are not all recessive.
• Option 4: In incomplete dominance, there are two alleles in the system (one dominant and one recessive).
• Option 5: In codominance, genes are not all recessive. And the description of incomplete dominance in this option is incorrect.

Answer:

In codominance, two alleles are expressed equally; in incomplete dominance, heterozygotes have an intermediate phenotype.