Each of these four organisms began life as a single 2n cell. cells in each organisms divided and differentiated. probably the single most important process that ensured genetic continuity in all four organisms was dna a) alliteration. b) replication. c) transcription. d) translation.

Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. why? molecules and active sites vary in size; only properly sized molecules can fit.there is a precise compatibility between the active site and the lactose molecule.specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed.reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.