Which describes a single enzyme? A. Exists in many different shapes and sizes. B. Takes part in only one type of chemical reaction. C. Slows down the process of chemical digestion. D. Is involved in many types of chemical reactions.

Which conditions are necessary for natural selection to occur? select all of the answers that apply. a. inheritable adaptations vary among individuals. b. the population size is increasing. c. more individuals are born than can survive. d. fitness varies among individuals. e. the environment changes suddenly and drastically.

In the diagram below, the northern hemisphere would be in what season at position a a.fall b. winter c.summer d.spring

Define the apical impulse and describe its normal location, size, and duration. which abnormal conditions may affect the location of the apical impulse? explain the mechanism producing normal first and second heart sounds. describe the effect of respiration on the heart sounds. describe the characteristics of the first heart sound and its intensity at the apex of the heart and at the base. describe the characteristics of the second heart sound and its intensity at the apex of the heart and at the base.