Answer:
1. SnapDragon - incomplete dominance
2. Cows/chickens- multiple alleles
3. Blood type in humans - co-dominance
4. Skin and hair color - polygenic inheritance
Explanation:
1. Sometimes, the phenotypic expression of a recessive allele cannot be completely covered by that of the dominant allele. This is called incomplete dominance. Flowers of snapdragon and four'o clock plants are the example of such an event where the recessive allele for flower color, which is white is also expressed in heterozygous plants along with the dominant red color, producing pink flowers.
2. Multiple alleles determine the genetic traits of cows and chickens.
3. There are three alleles in humans that determine the blood type - dominant Ia and Ib for A and B type respectively, and recessive Io for O type. when in a heterozygous person, both dominant alleles are present, both are expressed phenotypically forming AB type blood. this is called Co-dominance.
4. Skin and hair color in humans is determined by multiple alleles present in different chromosomes. this is called polygenic inheritance.