Evolution and Biology Key Terms Knowing the language of biology is the initial step in mastering the concepts. Beyond the definitions, you should be able to tell how each one fits into the big picture. Biosphere Ecosystem Community Population Organism (Organ) System Organ Tissue Cell Organelle Molecule Atom Reductionism Emergent Properties Eukaryotic Prokaryotic DNA Genes Gene Expression Domain Bacteria Domain Archaea Domain Eukarya Natural Selection Genome Inductive Reasoning Deductive Reasoning Hypothesis Control Group Experimental Group Independent Variable Dependendent Variable Theory