Question

Choose the correct answer from the alternatives given.
Which of the following is an example of codominance?

• A. Pink flowers of snapdragon
• B. The ABO blood groups in humans
• C. Sex-linkage in humans
• D. None of these

Answer 1

The correct option is B The ABO blood groups in humans

• Pink flowers of Snapdragon is a heterozygote phenotype and an intermediate phenotype of the two homozygous phenotypes from which it originates. It is an example of incomplete dominance.
• Codominance is seen when both the alleles are expressed simultaneously and neither of the alleles is dominant over the other. In human ABO blood grouping system both the alleles I${}^A$ and I${}^B$ are codominant and hence in the AB blood group individuals both the antigens, A and B are seen. So, the human ABO blood grouping is an example of codominance.
• The expression of the sex chromosomes in humans differ in males and females and hence are said to be sex-linked.

So, the correct option is 'The ABO blood groups in humans'.