You breed together a bean plant that has really long, skinny beans and a been plant with really short, fat beans. The offspring end up having medium length, medium width beans. This would be an example of what type of inheritance.
For a given trait, there are basically two types of alleles that are present. One allele is the dominant one and the other is recessive.
Generally , the phenotype of an individual corresponds to the one coded by the dominant allele when both the alleles are present for a given trait, that is if a heterozygous condition is there. However, in some cases the dominant allele is not completely dominant over the recessive allele.
When the dominant allele is not completely dominant then under heterozygous condition the phenotype expressed is a blend of the phenotypes expressed by both the alleles. For e.g if a red flower is crossed with white flower and we get a pink flower we can say that the allele shows partial dominance over the other.
Similarly in the given question, the dominant allele is partially dominant over the recessive allele thus, a blended phenotype appears in the progeny. Such type of inheritance is known as incomplete dominance, partial dominance or semi dominance.
