L14 Membranes

A  lipids

B  hydrophilic heads

C  Proteins

D  Carbohydrates

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  water moves into the slug, causing it to swell

B  water moves out of the slug, causing dehydration

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

D  salt moves into the slug, poisoning it

A  Osmosis

B  Concentration gradient

C  Semi-permeable

D  Diffusion

A  Hypertonic

B  Homeostasis

C  Isotonic

D  Hypotonic

A  Diffusion

B  Solution

C  Isotonic

D  Osmosis

A  impossible to tell

B  shrink

C  swell

D  stay the same size

A  osmotic pressure.

B  pinocytosis.

C  osmosis.

D  active transport.

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  Facilitated diffusion

B  Symport

C  Simple diffusion

D  Pump

A  secondary active transport

B  passive diffusion through the lipid bilayer

C  primary active transport

D  specific gas transport proteins

A  steroid lipids at certain temperatures

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

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

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

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

A  Cell membranes are impermeable to most molecules.

B  Cell membranes maintain the shape of cells.

C  Cell membranes are permeable to most inorganic ions.

D  Cell membranes retain the contents of cells.

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

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

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

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

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 saturated fatty acids in the glycerophosphate molecules that make up the bilayer.

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

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

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

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

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

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

A  cholesterol

B  proteins

C  None of the answers is correct.

D  ATP

E  magnesium ions

A  All of the answers are correct.

B  membrane melting temperatures.

C  membrane fluidity and membrane melting temperatures.

D  membrane fluidity

E  membrane asymmetry

A  Active transport

B  Diffusion through a uniport

C  facilitated diffusion

D  Passage through ion channels

A  unsaturated fatty acids.

B  free fatty acids.

C  glycolipids

D  lipids that contain sphingosine.

A  positioned equally on both sides of the membrane.

B  positioned on the inside center of the bilayer.

C  also covalently attached to membrane proteins

D  positioned on the intracellular side of the membrane.

E  positioned on the extracellular side of the membrane.

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  varying thickness, depending on structure

B  infinite

C  one

D  two

E  None of the answers is correct.

A  carbohydrates

B  lipids and proteins

C  None of the answers is correct.

D  All of the answers are correct

A  lipid-linked proteins

B  integral membrane proteins in contact with the cytoplasm

C  cholesterol

D  glycolipids

A  translocation

B  flip-flopping

C  asymmetric longitudinal flipping

D  kinesin-mediated movement

E  lateral diffusion

A  amphipathic nature

B  asymmetry

C  selective permeability

D  None of the answers is correct.

E  bilayer

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

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

A  Energy

B  Water

C  Concentrated solutes

D  Carrier proteins

A  An area of low concentration to an area of high concentration

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

C  An area of equilibrium to an area of high concentration

D  All of the above

A  pump

B  reducer

C  diffuser

D  transporter

E  oxidizer

A  active transport

B  osmosis

C  facilitated diffusion

D  diffusion

E  None of the choices are correct

A  An entropy increase powers diffusion across the membrane.

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

C  The outside surface of a beta barrel is hydrophylic

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

A  passive transport

B  primary active transport

C  secondary active transport

D  simple diffusion

E  facilitated diffusion

A  driven by a difference of solute concentration

B  driven by ATP

C  generally irreversible

D  not specific with respect to the substrate

E  endergonic

A  synthesizing thicker membranes to insulate the cell.

B  increasing its metabolic rate to generate more heat.

C  putting more unsaturated fatty acids into its membranes.

D  shifting from aerobic to anaerobic metabolism.

E  putting longer-chain fatty acids into its membranes.

A  a decrease in temperature.

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

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

D  an increase in fatty acyl chain length.

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 polar head groups face inward toward the inside 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  They can be removed from the membrane with high salt or mild denaturing agents.

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

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

A  a buffer

B  a solution of high ionic strength

C  a chelating agent that removes divalent cations

D  hot water

E  a solution containing detergent

A  are generally noncovalently bound to membrane lipids

B  may have functional units on both sides of the membrane

C  can be released from membranes only by treatment with detergents

D  penetrate deeply into the lipid bilayer