The medications ritalin and adderall, which are prescribed for the treatment of attention deficit hyperactivity disorder (adhd), act by decreasing norepinephrine and increasing dopamine activity increasing norepinephrine and decreasing dopamine activity decreasing norepinephrine and decreasing dopamine activity increasing norepinephrine and increasing dopamine activity

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.