Question

which inheritance pattern results when parents with pure traits are crossed and the resulting offspring have traits that appear to be a blend of the parents traits?
○ incomplete dominance
○ codominance
○ mendelian inheritance
○ polygenic inheritance

Explanation:

• Incomplete dominance: In this pattern, when two pure - trait parents (homozygous) are crossed, the offspring show a blended phenotype. For example, if a red - flowered plant (RR) and a white - flowered plant (rr) with incomplete dominance are crossed, the offspring (Rr) have pink flowers.
• Codominance: Here, both alleles are expressed simultaneously in the heterozygote. For example, in blood types, if a person has \(I^A\) and \(I^B\) alleles, they have AB blood type (both A and B antigens are present, not a blend).
• Mendelian inheritance (dominance): One allele is completely dominant over the other. For example, in pea plants, if a tall (TT) and a short (tt) plant are crossed, the \(F_1\) is all tall (Tt, the dominant allele T masks the recessive allele t).
• Polygenic inheritance: Multiple genes contribute to a single trait. For example, human skin color is controlled by multiple genes, and it is not a simple blend of two parental traits in the sense of a single - gene, two - allele system as described in the question.

Answer:

incomplete dominance