Final answer:
Complex heredity includes codominance, incomplete dominance, multiple alleles, polygenic inheritance, and sex-linked traits, which all differ from simple Mendelian inheritance patterns. Traits like blood type exhibit codominance and multiple alleles, while traits influenced by multiple genes, such as height, display polygenic inheritance. Sex-linked traits are inherited via sex chromosomes.
Step-by-step explanation:
The various types of complex heredity that deviate from Mendel's simple dominance model include codominance, incomplete dominance, multiple alleles, polygenic inheritance, and sex-linked traits.
- Incomplete dominance is a type of inheritance where the heterozygote exhibits a phenotype that is intermediate between the phenotypes of the two homozygotes. For example, when a red-flowered plant is crossed with a white-flowered plant, the offspring may have pink flowers.
- Codominance occurs when both alleles in a heterozygote are fully expressed, resulting in a phenotype where both traits are displayed simultaneously. A classic example is the human ABO blood typing system, where individuals with type AB blood express both A and B antigens on their red blood cells.
- Multiple alleles refer to genes that have more than two allelic forms within the population. The ABO blood group system is also an example of multiple alleles, with the A, B, and O alleles.
- Polygenic inheritance involves multiple genes contributing to a single trait, such as skin color or height, resulting in a continuous range of phenotypes.
- Sex-linked traits are associated with genes located on sex chromosomes, often the X chromosome. Because males have only one X chromosome (XY), they will express whatever allele is present on that chromosome, while females (XX) can be heterozygous or homozygous for those genes. Examples include color blindness and hemophilia.