Which of the following problems are environmental indicators of acid deposition? Decreased pH levels in lakes and rivers
Decreased concentration of aluminum in the soil
Changes in development of indicator organisms of an ecosystem
II only
III only
I and III
I and II

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.