A.   may have functional units on both sides of the membrane

B.   can be released from membranes only by treatment with detergents

C.   penetrate deeply into the lipid bilayer

D.   are generally noncovalently bound to membrane lipids

A.   hot water

B.   a chelating agent that removes divalent cations

C.   a solution of high ionic strength

D.   a buffer

E.   a solution containing detergent

A.   They can be removed from the membrane with high salt or mild denaturing agents.

B.   The secondary structure in the transmembrane region consists solely of alpha-helices or beta-sheets.

C.   The domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides.

D.   They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer.

A.   Individual lipid molecules are free to diffuse laterally in the surface of the bilayer.

B.   Individual lipid molecules in one face (monolayer) of the bilayer readily diffuse (flip-flop) to the other monolayer.

C.   The bilayer is stabilized by covalent bonds between neighboring phospholipid molecules.

D.   Polar, but uncharged, compounds readily diffuse across the bilayer.

E.   The polar head groups face inward toward the inside of the bilayer.

A.   an increase in fatty acyl chain length.

B.   the binding of water to the fatty acyl side chains.

C.   a decrease in temperature.

D.   an increase in the number of double bonds in fatty acids.

A.   putting longer-chain fatty acids into its membranes.

B.   synthesizing thicker membranes to insulate the cell.

C.   increasing its metabolic rate to generate more heat.

D.   putting more unsaturated fatty acids into its membranes.

E.   shifting from aerobic to anaerobic metabolism.

A.   driven by a difference of solute concentration

B.   endergonic

C.   driven by ATP

D.   generally irreversible

E.   not specific with respect to the substrate

A.   simple diffusion

B.   secondary active transport

C.   facilitated diffusion

D.   primary active transport

E.   passive transport

A.   There are electrostatic and hydrogen-bonding attractions between the polar head groups and water molecules.

B.   The outside surface of a beta barrel is hydrophylic

C.   An entropy increase powers diffusion across the membrane.

D.   In accord with the Second Law of Thermodynamics, molecules spontaneously move from a region of higher concentration to one of lower concentration

A.   diffusion

B.   None of the choices are correct

C.   osmosis

D.   active transport

E.   facilitated diffusion

A.   oxidizer

B.   transporter

C.   diffuser

D.   pump

E.   reducer

A.   An area of equilibrium to an area of high concentration

B.   An area of low concentration to an area of high concentration

C.   An area of high concentration to an area of low concentration

D.   All of the above

A.   Energy

B.   Concentrated solutes

C.   Water

D.   Carrier proteins

A.   The transport of a molecule up its gradient is an exergonic process

B.   Movement of one molecule down its gradient is an entropically driven process

C.   The transport of a molecule up its gradient is an energy-requiring process.

D.   Passage through a channel allows polar and charged compounds to avoid the hydrophobic core of the plasma membrane, which would otherwise block their entry into the cell.

A.   amphipathic nature

B.   None of the answers is correct.

C.   bilayer

D.   selective permeability

E.   asymmetry

A.   translocation

B.   kinesin-mediated movement

C.   lateral diffusion

D.   asymmetric longitudinal flipping

E.   flip-flopping

A.   glycolipids

B.   cholesterol

C.   integral membrane proteins in contact with the cytoplasm

D.   lipid-linked proteins

A.   lipids and proteins

B.   None of the answers is correct.

C.   carbohydrates

D.   All of the answers are correct

A.   one

B.   None of the answers is correct.

C.   varying thickness, depending on structure

D.   two

E.   infinite

A.   a bilayer made of lipids with polyunsaturated 18 carbon-fatty acids

B.   a bilayer made of lipids with saturated 18 carbon-fatty acids

C.   a bilayer made of lipids with polyunsaturated 16 carbon-fatty acids

D.   a bilayer made of lipids with saturated 16 carbon-fatty acids

E.   All of the above are equivalent in fluidity.

A.   positioned on the inside center of the bilayer.

B.   positioned equally on both sides of the membrane.

C.   also covalently attached to membrane proteins

D.   positioned on the extracellular side of the membrane.

E.   positioned on the intracellular side of the membrane.

A.   free fatty acids.

B.   glycolipids

C.   unsaturated fatty acids.

D.   lipids that contain sphingosine.

A.   Passage through ion channels

B.   Active transport

C.   facilitated diffusion

D.   Diffusion through a uniport

A.   membrane fluidity and membrane melting temperatures.

B.   All of the answers are correct.

C.   membrane asymmetry

D.   membrane melting temperatures.

E.   membrane fluidity

A.   magnesium ions

B.   proteins

C.   ATP

D.   cholesterol

E.   None of the answers is correct.

A.   Lateral movement of membrane lipids occurs rapidly within the plane of the bilayer.

B.   Transverse movement of membrane lipids within the bilayer is unrestricted.

C.   The inner and outer halves of the lipid bilayer are identical.

D.   Lateral movement of membrane lipids is catalysed by special proteins.

A.   Membrane fluidity is increased when there is a high proportion of cis unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

B.   Membrane fluidity is increased when there is a high proportion of trans unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

C.   Membrane fluidity is decreased when there is a high proportion of cis unsaturated fatty acids in the glycerophosphate molecules that make up the bilayer.

D.   Membrane fluidity is increased when there is a high proportion of saturated fatty acids in the glycerophosphate molecules that make up the bilayer.

A.   Integral membrane proteins are anchored to the lipid bilayer by ionic bonds.

B.   Integral membrane proteins have ends rich in hydrophilic amino acids.

C.   Integral membrane proteins have transmembrane domains rich in hydrophobic amino acids.

D.   Transmembrane porins have hydrophilic amino acids that point inwards in the beta-barrels.

A.   Cell membranes retain the contents of cells.

B.   Cell membranes are permeable to most inorganic ions.

C.   Cell membranes maintain the shape of cells.

D.   Cell membranes are impermeable to most molecules.

A.   Small polar molecules require specific transport systems for passage across a membrane.

B.   Small polar molecules cannot be transported through a cell membrane against a concentration gradient.

C.   Small polar molecules can diffuse through a cell membrane along a concentration gradient.

D.   Small inorganic ions can diffuse through a cell membrane along a concentration gradient.

A.   cholesterol at certain temperatures

B.   steroid lipids at certain temperatures

C.   double bonds between carbon atoms in the fatty acid tails

D.   poor alignment of the fatty acids tails

E.   all of the above

A.   primary active transport

B.   secondary active transport

C.   passive diffusion through the lipid bilayer

D.   specific gas transport proteins

A.   Simple diffusion

B.   Facilitated diffusion

C.   Symport

D.   Pump

A.   move across the membrane to the outside of the cell.

B.   move across the membrane to the inside of the cell.

C.   continue to move across the membrane in both directions.

D.   stop moving across the membrane.

A.   osmosis.

B.   pinocytosis.

C.   osmotic pressure.

D.   active transport.

A.   swell

B.   shrink

C.   impossible to tell

D.   stay the same size

A.   Solution

B.   Isotonic

C.   Diffusion

D.   Osmosis

A.   Homeostasis

B.   Isotonic

C.   Hypertonic

D.   Hypotonic

A.   Osmosis

B.   Concentration gradient

C.   Diffusion

D.   Semi-permeable

A.   water moves out of the slug, causing dehydration

B.   salt moves out of the slug, depriving it of essential minerals

C.   water moves into the slug, causing it to swell

D.   salt moves into the slug, poisoning it

A.   a bilayer made of lipids with polyunsaturated 16 carbon-fatty acids

B.   a bilayer made of lipids with polyunsaturated 18 carbon-fatty acids

C.   a bilayer made of lipids with saturated 18 carbon-fatty acids

D.   a bilayer made of lipids with saturated 16 carbon-fatty acids

E.   All of the above are equivalent in fluidity.

A.   hydrophilic heads

B.   Carbohydrates

C.   lipids

D.   Proteins