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List three common cellular substances that can pass through cell membranes unaided.

Macronutrients _________. A. include carbohydrates and vitamins; B. should comprise a small percentage of a healthful diet; \(\mathbf{C}\). are essential in minute amounts to help enzymes function; D. include carbohydrates, fats, and proteins; E. are synthesized by cells and not necessary to obtain from the diet.

Which of the following is not a function of water? A. dispersing nutrients throughout the body; B. helping the body eliminate digestive wastes; \(\mathrm{C}\). helping to regulate body temperature; D. helping to regulate blood pressure.

The main constituents of the plasma membrane are ______. A. carbohydrates and lipids; B. proteins and phospholipids; C. fats and carbohydrates; D. fatty acids and nucleic acids.

A substance moving across a membrane against a concentration gradient is moving by ________. A. passive transport; B. osmosis; C. facilitated diffusion; D. active transport; E. diffusion.

A cell that is placed in salty seawater will ________. A. take sodium and chloride ions in by diffusion; B. move water out of the cell by active transport; C. use facilitated diffusion to break apart the sodium and chloride ions; D. lose water to the outside of the cell via osmosis.

Which of the following forms of membrane transport require specific membrane proteins? A. diffusion; B. exocytosis; C. facilitated diffusion; D. active transport; E. facilitated diffusion and active transport.

Water crosses cell membranes _______. A. by active transport; B. through protein pores called aquaporins; C. against its concentration gradient; D. in plant cells but not in animal cells.