Answer:
Among the options provided, carriers of sickle-cell anemia in the human population is not an example of codominance.
Codominance refers to a genetic scenario where both alleles of a gene are expressed equally in the phenotype of an individual. This means that neither allele is dominant over the other, and both contribute to the observable trait.
Let's consider the options provided:
1. Plumage color of Andalusian fowls: This is an example of codominance. When a black-feathered Andalusian chicken (BB) is crossed with a white-feathered Andalusian chicken (WW), the resulting offspring (BW) exhibit a unique blue plumage color where both black and white feathers are expressed.
2. Skin color in short-horned cattle: This is also an example of codominance. In short-horned cattle, there are two alleles for coat color: red (RR) and white (WW). When a red-coated cow is crossed with a white-coated bull, the resulting offspring (RW) display a roan or mottled coat color, with both red and white hairs evenly distributed.
3. AB blood group in humans: This is an example of codominance. The AB blood type is formed when an individual inherits both the A and B alleles for blood type from their parents. Both A and B antigens are present on the surface of their red blood cells, resulting in the AB blood group.
4. Carriers of sickle-cell anemia in the human population: This is not an example of codominance. Sickle-cell anemia is caused by a mutation in the hemoglobin gene, specifically in the beta-globin subunit. Carriers of sickle-cell anemia have one normal allele and one mutated allele (Ss). In this case, the mutated allele (s) is recessive to the normal allele (S), and carriers do not exhibit symptoms of the disease. Therefore, it does not demonstrate codominance.
In conclusion, option (4) carriers of sickle-cell anemia in the human population is not an example of codominance.
Step-by-step explanation: