What are major inheritance patterns beyond simple dominance, and what are their examples?

• A. Incomplete dominance produces a blending phenotype (pink) from red and white alleles; Codominance yields both traits simultaneously (AB blood); Multiple alleles exist for ABO; Polygenic traits involve many genes (like height).
• B. Incomplete dominance means a trait is fully dominant; Codominance means neither allele is expressed.
• C. Multiple alleles are when a trait is controlled by a single gene with two alleles; Polygenic traits are single-gene traits.
• D. Codominance occurs only in bacteria; In humans ABO show complete dominance.

Answer: (A)

This question centers on inheritance patterns that go beyond simple dominance, highlighting incomplete dominance, codominance, multiple alleles, and polygenic traits with concrete examples. Incomplete dominance shows a blended phenotype in the heterozygote, such as red x white offspring producing pink. Codominance means both alleles are expressed together, as seen with ABO blood types where A and B antigens are both present in type AB. Multiple alleles means a gene has more than two allele options in the population, which is true for the ABO gene that has IA, IB, and i, giving more possible phenotypes than a two-allele system. Polygenic traits arise from the combined effects of many genes, producing continuous variation like height. These patterns illustrate the diversity of genetic inheritance beyond a single dominant-recessive relationship.