Select all that apply.
microevolution
1. refers to evolution at or below the species level
2. includes evolution at the population and community level
3. analyzes the history of life over time
4. refers to evolution above the species level
5. is based on direct observation

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.