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Multiple Choice
In the human blood type AB, both alleles are expressed and are therefore __________.
A
polygenic
B
dominant
C
sex-linked
D
codominant
E
incompletely dominant
Verified step by step guidance
1
Understand the concept of alleles: Alleles are different forms of a gene that can exist at a specific locus. In the case of blood type, the alleles determine the antigens present on the surface of red blood cells.
Learn about codominance: Codominance occurs when both alleles in a heterozygous organism are fully expressed, resulting in a phenotype that displays characteristics of both alleles equally.
Apply the concept to blood type AB: In blood type AB, both the A and B alleles are expressed equally, meaning neither allele is dominant over the other. This is a classic example of codominance.
Differentiate from other genetic terms: Polygenic traits involve multiple genes, dominant traits mask the expression of recessive alleles, sex-linked traits are associated with genes on sex chromosomes, and incomplete dominance results in a blend of traits.
Conclude with the correct term: Given the expression of both alleles in blood type AB, the correct term to describe this genetic phenomenon is 'codominant'.