1. when might preserved remains of an entire organism form? a. when sediment buries the hard part of an organism. b. when an event such as a quick burial or freezing preserves an entire organism. c. when minerals replace parts of an organism. d. when a thin layer of carbon is left on a rock 2. which of the following fossil types is formed when minerals replace all or part of an organism's body? a. a mold. b. a petrified fossil. c. a cast. d. a trace fossil

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.