Biology Test Questions

facilitated diffusion across a biological membrane requires _____ and moves a substance ____ its concentration gradient. a. energy and transport proteins...against b. transport proteins...down c. energy...down d. transport proteins...against

b

osmosis can be defined as... a. endocytosis b. the diffusion of nonpolar molecules. c. the diffusion of water across a selectively permeable membrane. d. the diffusion of a solute

c

A cell that neither gains nor loses water when it is immersed in a solution is... a. hypertonic to its environment b. hypotonic to its environment c. metabolically inactive d. isotonic to its environment

d

diffusion is an example of... a. passive transport b. exocytosis c. endocytosis d. active transport

a

Plasma membranes are selectively permeable. This means that... a. anything can pass into or out of a cell as long as the membranes is intact and the cell is healthy. b. The plasma membrane allows some substances to enter or leave a cell more easily than others. c. plasma membranes must be very thick d. glucose can not enter the cell

b

the phospholipids in cell membranes... a. have strong bonds between them b. are held in place by hydrophilic/hydrophobic interactions c. create an impermeable barrier that prevents materials from entering or leaving cells. d. are rigid, infexible, an unable to move.

b

active transport... a. uses ATP as an energy source b. requires the cell to expend energy c. can move solutes against their concentration gradient d. all of the above

d

the fluid mosaic models describes the plasma membrane as consisting of... a. a solid layer of proteins with phospholipids distributed throughout. b. a phospholipid bilayer with embedded carbohydrates. c. a protein bilayer with embedded phospholipids. d. a phospholipid bilayer with proteins scattered throughout.

d