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

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

C.   penetrate deeply into the lipid bilayer

D.   are generally noncovalently bound to membrane lipids

A.   a solution of high ionic strength

B.   a chelating agent that removes divalent cations

C.   hot water

D.   a buffer

E.   a solution containing detergent

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

B.   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.

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

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

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

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

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

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

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

A.   an increase in fatty acyl chain length.

B.   a decrease in temperature.

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

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

A.   shifting from aerobic to anaerobic metabolism.

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

C.   increasing its metabolic rate to generate more heat.

D.   synthesizing thicker membranes to insulate the cell.

E.   putting more unsaturated fatty acids into its membranes.

A.   endergonic

B.   generally irreversible

C.   driven by ATP

D.   driven by a difference of solute concentration

E.   not specific with respect to the substrate

A.   simple diffusion

B.   secondary active transport

C.   facilitated diffusion

D.   passive transport

E.   primary active transport

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

B.   The outside surface of a beta barrel is hydrophylic

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

D.   An entropy increase powers diffusion across the membrane.

A.   None of the choices are correct

B.   diffusion

C.   facilitated diffusion

D.   active transport

E.   osmosis

A.   reducer

B.   transporter

C.   oxidizer

D.   pump

E.   diffuser

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

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

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

D.   All of the above

A.   Concentrated solutes

B.   Water

C.   Energy

D.   Carrier proteins

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

B.   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.

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

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

A.   amphipathic nature

B.   asymmetry

C.   bilayer

D.   selective permeability

E.   None of the answers is correct.

A.   asymmetric longitudinal flipping

B.   kinesin-mediated movement

C.   flip-flopping

D.   lateral diffusion

E.   translocation

A.   cholesterol

B.   integral membrane proteins in contact with the cytoplasm

C.   lipid-linked proteins

D.   glycolipids

A.   All of the answers are correct

B.   carbohydrates

C.   lipids and proteins

D.   None of the answers is correct.

A.   infinite

B.   varying thickness, depending on structure

C.   one

D.   None of the answers is correct.

E.   two

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

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

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

D.   a bilayer made of lipids with polyunsaturated 18 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.   positioned on the intracellular side of the membrane.

D.   positioned on the extracellular side of the membrane.

E.   also covalently attached to membrane proteins

A.   glycolipids

B.   free fatty acids.

C.   lipids that contain sphingosine.

D.   unsaturated fatty acids.

A.   Diffusion through a uniport

B.   Active transport

C.   facilitated diffusion

D.   Passage through ion channels

A.   membrane fluidity and membrane melting temperatures.

B.   membrane asymmetry

C.   membrane melting temperatures.

D.   membrane fluidity

E.   All of the answers are correct.

A.   proteins

B.   ATP

C.   magnesium ions

D.   None of the answers is correct.

E.   cholesterol

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

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

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

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

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

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

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

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

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

A.   Cell membranes are impermeable to most molecules.

B.   Cell membranes are permeable to most inorganic ions.

C.   Cell membranes maintain the shape of cells.

D.   Cell membranes retain the contents of cells.

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

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

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

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

A.   poor alignment of the fatty acids tails

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

C.   steroid lipids at certain temperatures

D.   cholesterol at certain temperatures

E.   all of the above

A.   primary active transport

B.   specific gas transport proteins

C.   passive diffusion through the lipid bilayer

D.   secondary active transport

A.   Facilitated diffusion

B.   Simple diffusion

C.   Pump

D.   Symport

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

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

C.   stop moving across the membrane.

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

A.   active transport.

B.   osmosis.

C.   osmotic pressure.

D.   pinocytosis.

A.   stay the same size

B.   shrink

C.   swell

D.   impossible to tell

A.   Solution

B.   Isotonic

C.   Osmosis

D.   Diffusion

A.   Hypertonic

B.   Homeostasis

C.   Isotonic

D.   Hypotonic

A.   Concentration gradient

B.   Semi-permeable

C.   Osmosis

D.   Diffusion

A.   salt moves into the slug, poisoning it

B.   water moves out of the slug, causing dehydration

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

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

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

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

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

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

E.   All of the above are equivalent in fluidity.

A.   hydrophilic heads

B.   lipids

C.   Proteins

D.   Carbohydrates