Singer and Nicolson's fluid mosaic model of the membrane proposed that

A) membranes are a phospholipid bilayer. B) membranes are a phospholipid bilayer between two layers of hydrophilic proteins. C) membranes are a single layer of phospholipids and proteins. D) membranes consist of protein molecules embedded in a fluid bilayer of phospholipids. E) membranes consist of a mosaic of polysaccharides and proteins.

D

An animal cell membrane will be more fluid at room temperature if it contains

A) more cholesterol. B) longer chain fatty acids. C) more cis-unsaturated and polyunsaturated fatty acids. D) more trans-unsaturated fatty acids. E) any of the above

C

Which of these processes can move a solute against its concentration gradient?

A) osmosis B) passive transport C) facilitated diffusion D) active transport

D

An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?

A) transporting ions against an electrochemical gradient B) cell-cell recognition C) maintaining fluidity of the phospholipid bilayer D) attaching to the cytoskeleton E) establishing the diffusion barrier to charged molecules

B

Which of the following proteins is not necessarily associated with the plasma membrane?

A) recognition protein B) plasma protein C) receptor protein D) channel protein

B

Which of the following affects the rate of diffusion through a selectively permeable membrane? I. concentration gradient II. temperature III. molecular size A).I only B) II only C) I and II D) I, II, and III

D

The movement of potassium into an animal cell requires

A) low cellular concentrations of sodium. B) high cellular concentrations of potassium. C) an energy source such as ATP. D) a cotransport protein. E) a potassium channel protein.

C

Which of the following molecules will diffuse most quickly across a lipid bilayer membrane?

A) H2O B) O2 C) H2PO4- D) glucose E) Na+

B

This illustration shows the mechanism of

A) simple diffusion. B) bulk flow. C) endocytosis. D) facilitated diffusion

C

When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?

A) The cell will burst. B) The cell membrane will lyse. C) Plasmolysis will shrink the interior. D) The cell will become flaccid. E) The cell will become turgid.

E