What do the arrows in a food chain represent?

Amap's orientation is typically determined by an

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.

Many birth-control pills release a constant amount of synthetic estradiols and progesterone for 21 days. true or false