Q. Scientists recently have proposed a reorganization of the phylogenetic system of classification to include the domain, a new taxonomic category higher (more inclusive) than the Kingdom category.

• explain how this classification scheme presents different conclusions about the relationships among living organisms than those presented by the previous five-kingdom system of classification.

• illustrate three kinds of evidence that were used to develop the taxonomic scheme above, and explain how this evidence was used. The evidence may be structural, physiological, molecular, and genetic.

• explain four of the characteristics of the universal ancestor.