Elements are made from one type of matter.
The classification is in this order: Kingdom, Phylum, Class, Order, Family, Genus Species.
The kingdom is the largest group, it contains the largest number of organisms who are the least related.
The species is the smallest group, it contains the least number of organisms who are closely related.
As you go down, from "Kingdom", species become more closely related.
So species in the same family are MORE closely related than species in the same class.
Dominant refers to the relationship between two versions of a gene. Individuals receive two versions of each gene, known as alleles, from each parent. If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. The effect of the other allele, called recessive, is masked.