When an atom manages to get its outer energy level filled with electrons the atom becomes a. non-reactive. b. more reactive. c. very unstable. d. a new element.

answer; ///(b) it is composed of four protein chains and four heme groups;

many phylogenetic trees have a single lineage at the base representing a common ancestor. a lineage that evolved early from the root and remains unbranched is called basal taxon. when two lineages stem from the same branch point, they are called sister taxa.

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explanation: