Which of the following can be used by scientists to date the sediment layer they are found in? select all that apply.

radioactive isotopes
fossils
tree rings
animal growth rings
mineral elements

need answers asap

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.