Answer to Question 1
B
Facilitated diffusion allows absorption of molecules into cells from an area of low concentration to an area of high concentration; it uses a carrier protein but does not require energy. In pinocy-tosis a nutrient or liquid is engulfed by part of the cell membrane and taken into the cell in a va-cuole. Passive diffusion does not use a special carrier protein; nutrients pass from an area of high concentration to an area of low concentration.
Answer to Question 2
2
Rationale: A positive nitrogen balance exists when nitrogen intake exceeds losses. A growing, active adolescent is likely to have a positive nitrogen balance to meet rapid growth and development needs. A college student is likely to have nitrogen equilibrium since nitrogen is no longer needed for rapid growth and development. The adults who have significant health problems are in a state of negative nitrogen balance.