Deck 3: The Plasma Membrane and Membrane Potential

Question 1

The rate at which "X" can diffuse through a plasma membrane is inversely proportional to the

A)lipid solubility of X
B)concentration gradient for X
C)molecular weight of X
D)membrane's surface area
E)lipid solubility and molecular weight of X

Answer 1

C

Question 2

Which of the following is not associated with an extracellular chemical binding with a membrane-bound receptor?

A)Decreased activity within a certain cell
B)Activation of an ATPase
C)A change in shape of a transmembrane protein
D)Increased activity within a certain cell
E)Opening of a sodium channel that allows Na+ to diffuse out of the cell

Answer 2

E

Question 3

The plasma membrane

A)has a slight excess of positive charges along its cytosol side during the resting state
B)is composed primarily of cholesterol surrounded by carbohydrates
C)is more permeable to K+ than to Na+ at the resting state
D)has peripheral proteins that act as carriers
E)exhibits all of the characteristics listed above

Answer 3

C

Question 4

Identify the incorrect statement about the plasma membrane.

A)Cholesterol contributes to its stability.
B)Its lipids may surround CAMs.
C)Its primary components are glycoproteins and cholesterol.
D)Its lipid bilayer is flexible.
E)Its glycocalyx is in contact with ECF.

Question 5

Which extracellular fiber does not develop properly in scurvy?

A)actin
B)collagen
C)elastin
D)fibronectin
E)myosin

Question 6

Collagen

A)provides tensile strength to the cytoskeleton
B)is most abundant in tissues that stretch and then recoil
C)forms the intercellular filaments of desmosomes
D)is the most abundant protein in the ECM
E)all of these

Question 7

Which statement about the plasma membrane is true?

A)It appears trilaminar under a light microscope.
B)Its glycocalyx serves as receptor sites for binding chemical messengers in the ECF.
C)It is impermeable to lipid-soluble substances.
D)Some of its carriers transport ions.
E)Its channels are impermeable to any substance smaller than 0.8 nm in diameter.

Question 8

Receptor sites on the outer surface of the plasma membrane are made of

A)CAMs
B)carbohydrate
C)lipid
D)keratin
E)proteins

Question 9

Which statement about membrane proteins is incorrect?

A)Channels are water-filled pathways.
B)Channels are not highly selective.
C)Carriers are highly selective.
D)CAMs serve as binding sites for specific ions.
E)Proteins may work in conjunction with carbohydrates to provide recognition of "self."

Question 10

Cystic fibrosis is caused by abnormal

A)accumulation of mucus
B)levels of insulin
C)chloride channels in plasma membranes
D)potassium channels in plasma membranes
E)sodium-potassium pumps

Question 11

Identify the true statement(s) about the plasma membrane.

A)Its lipid region allows most ions to diffuse between the cytosol and ECF.
B)Its channels allow cholesterol to diffuse between the ECF and cytosol.
C)Some of its carriers transport sodium.
D)Its phospholipids are held to one another by CAMs.
E)All except its phospholipids are held to one another by CAMs.

Question 12

Identify the true statement(s) about the plasma membrane.

A)Its transmembrane proteins are also peripheral proteins.
B)Its glycocalyx functions in cell recognition.
C)Its carriers contain cholesterol.
D)Its channels allow passage of substances between 0.8 nm and 1 nm in diameter.
E)Its transmembrane proteins are also peripheral proteins, and its channels allow passage of substances between 0.8 nm and 1 nm in diameter.

Question 13

Which statement about gap junctions is incorrect?

A)They consist of protein.
B)They are anchored to plaques on the inside surface of the plasma membrane.
C)They allow materials to pass from one cell into an adjacent cell.
D)They play a role in transmitting electrical activity through the heart.
E)They consist of connexons.

Question 14

Integrins

A)create a filamentous meshwork in the inner surface of the membrane
B)act as membrane-bounded enzymes
C)are used for cell recognition purposes
D)span the membrane and link the plasma membrane and the cell's surrounding
E)do not exhibit any of the above characteristics

Question 15

Which of the following is not a function of membrane proteins?

A)Some act as channels.
B)They determine the fluidity of the membrane.
C)Some will transport glucose.
D)They include docking-marker acceptors.
E)Some act as enzymes.

Question 16

Which of the following is not part of the extracellular matrix?

A)complex carbohydrates
B)connexons
C)collagen
D)elastin
E)fibronectin

Question 17

Which one of the following requires assisted membrane transport?

A)Glucose moving into a cell
B)K+ ions moving out of a cell
C)Water moving toward a hypertonic solution
D)Movement of ECF into a cell via pinocytosis
E)Movement of Na+ through a symporter

Question 18

A single phospholipid in the plasma membrane

A)has its hydrophobic end next to either the ECF or the cytosol
B)spans the entire width of the membrane
C)can function as carrier molecule
D)remains in the same location indefinitely
E)does not exhibit any of the above characteristics

Question 19

Select the substance that promotes cell adhesion.

A)GLUT
B)collagen
C)elastin
D)fibronectin
E)glycolipid

Question 20

The plasma membrane

A)appears under an electron microscope as a double dark line with a light space between
B)is composed primarily of a double layer of protein molecules with cholesterol molecules interspersed between them
C)has a hydrophilic region between two hydrophobic regions
D)has all of the above characteristics
E)does not exhibit any of the above characteristics

Question 21

Selective permeability of the membrane is primarily determined by

A)membrane phospholipids
B)how much cholesterol is present
C)the number and type of membrane proteins
D)the charge of the membrane
E)none of these

Question 22

In a plasma membrane, simple diffusion of various substances can occur

A)through channels
B)through carriers
C)between phospholipid molecules
D)through aquaporins
E)into the cell but not out of the cell

Question 23

An electrical gradient

A)favors the movement of K+ out of the cell at resting potential
B)favors the movement of Na+ into the cell at resting potential
C)opposes the concentration gradient for Na+ at the equilibrium potential for Na+
D)favors the movement of Cl- out of the cell at resting potential
E)prevents the active transport of K+ into the cell

Question 24

If a typical body cell is placed into a 1% saline solution, the cell

A)will gain more water than it loses.
B)will have a higher osmotic pressure than the ECF.
C)will have a lower hydrostatic pressure than the ECF.
D)will gain and lose water at the same rate.
E)will have a lower osmolarity than the saline solution.

Question 25

The rate of diffusion for water-soluble substances through a membrane decreases as

A)their concentration gradient increases
B)their molecular weight increases
C)the number of cholesterol molecules in the membrane increases
D)the membrane's surface area increases
E)the number of membrane carbohydrates increases

Question 26

If osmosis is occurring, then you know there is a net movement of water to an area of

A)lower osmotic pressure
B)higher hydrostatic pressure
C)higher solute concentration
D)higher water concentration
E)lower osmotic pressure and higher water concentration

Question 27

Which of the following is correct?

A)Exocytosis decreases the surface area of the plasma membrane.
B)Endocytosis can help remove cytoplasmic debris from inside the cell.
C)Exocytosis is triggered by the binding of a particle in the ECF to a receptor site on the plasma membrane.
D)Exocytosis involves passive movement of material out of the cell.
E)None of these.

Question 28

Select the correct statement about diffusion through a membrane.

A)It depends on random motion.
B)It involves active forces.
C)Its rate increases as the membrane's surface area decreases.
D)Ions move from a lower concentration to a higher concentration.
E)Large molecules diffuse faster than small molecules.

Question 29

During osmosis,

A)water moves away from the solution with the higher osmotic pressure.
B)water moves into a hypotonic solution.
C)the solute moves against its concentration gradient.
D)all of the above events would occur.
E)none of the above events would occur.

Question 30

Which of the following can diffuse between a membrane's phospholipids into the cytosol?

A)glucose
B)sodium
C)carbon dioxide
D)integrin molecule
E)a small secretory product

Question 31

Facilitated diffusion

A)involves a membrane channel
B)requires the cell to expend expenditure
C)is how glucose in the intestinal lumen moves into cells in the digestive lining
D)is a form of active transport
E)None of the above

Question 32

Tight junctions

A)prevent passage of materials into epithelial cells
B)force materials to pass between cells
C)are commonly found in digestive tract linings
D)comprise part of the glycocalyx
E)consist of cadherin proteins

Question 33

The concentration gradient for

A)K+ favors its movement into the ECF
B)Na+ favors its movement out of the cytosol
C)K+ and Na+ are maintained by active transport
D)Na+ opposes the electrical gradient for Na+
E)Cl- favors its movement out of the cytosol

Question 34

Which of the following is least related to glucose uptake by different cells in the body?

A)receptor-mediated endocytosis
B)facilitated diffusion
C)carrier-mediated transport
D)secondary active transport
E)cotransport

Question 35

Which statement about movement into the cytosol is false?

A)If glucose and sodium can both combine with the same carrier, the presence of one of these molecules decreases the rate of entry of the other.
B)In simple diffusion, the rate of entry of an ion is directly proportional to its concentration in the cytosol.
C)When a glucose symporter becomes saturated, the rate of glucose entry decreases.
D)None of the statements are false.
E)All of the statements are false.

Question 36

____ are adhering junctions, ____ are impermeable junctions, and ____ are communicating junctions.

A)Tight junctions, gap junctions, desmosomes
B)Desmosomes, gap junctions, tight junctions
C)Gap junctions, desmosomes, tight junctions
D)Gap junctions, tight junctions, desmosomes
E)Desmosomes, tight junctions, gap junctions

Question 37

Which of the following solutions has a lower osmotic pressure than a human cell's cytosol?

A)2% NaCl
B)200 mOsm of NaCl
C)0.9% NaCl
D)300 mOsm of NaCl
E)280 mOsm of glucose

Question 38

Carrier-mediated transport

A)involves a specific membrane protein
B)always moves substances against a concentration gradient
C)always requires energy expenditure
D)involves protein channels
E)all of these

Question 39

Two ATP molecules could provide energy for a sodium-potassium pump to move ____ ions out of the cell for every ____ ions it moves into the cell.

A)6 Na+; 3 K+
B)2 Na+; 3 K+
C)3 K+; 6 Na+
D)3 K+; 2 Na+
E)12 Na+; 6 K+

Question 40

Solution 1 has two solutes (A and B) and an osmotic pressure of 250 mOsm.Solution 2 has only one solute (C) and an osmotic pressure of 300 mOsm.If a membrane between these solutions is permeable to only water and B, then

A)Solution 1 will gain water from solution 2.
B)Solution 2 will gain water from solution 1.
C)Some of solute C will move into solution 1.
D)Solution 1 has a higher osmotic pressure.
E)Solution 1 would be hypertonic to a human cell.

Question 41

Which of the following would not require a carrier?

A)Movement of potassium into the cell
B)Movement of sodium into the cell
C)Iodine uptake by thyroid gland cells
D)Glucose uptake by body cells
E)None of the above would require a carrier.

Question 42

Which statement would be true at a membrane during its resting membrane potential?

A)It is more permeable to K+ than to Na+.
B)It is highly permeable to Cl-.
C)The electrical gradient for Cl- opposes its concentration gradient
D)All of the above statements are true.
E)Only b and c are true

Question 43

The rate of carrier-mediated transport is limited by

A)the glycocalyx
B)osmolarity
C)tonicity
D)competition with other molecules
E)the number of protein channels present in the membrane

Question 44

Glucose enters some cells

A)through primary active transport
B)through secondary active transport
C)through facilitated diffusion
D)all of the above processes
E)through A and C only

Question 45

According to Fick's law of diffusion, which of the following changes would decrease the rate of net diffusion of "X" across a membrane?

A)An increase in the X's concentration gradient
B)An increase in the permeability of the membrane to X
C)An increase in the surface area of the membrane
D)An increase in the thickness of the membrane
E)A decrease in the size of X

Question 46

Osmosis is a type of

A)carrier-mediated transport
B)diffusion
C)exocytosis
D)pinocytosis
E)primary active transport

Question 47

Cell X has a resting potential of -80 mV.If a ____ opens and causes the potential to change 10 mV, the resulting potential will be ____.

A)Na+ channel; -90 mV
B)K+ channel; -70 mV
C)Ca₂₊ channel; -70 mV
D)Cl- channel; -70 mV
E)Ca+2 channel; -90 mV

Question 48

During the resting potential

A)K+ ions leave the cell along a concentration gradient and along an electrical gradient.
B)K+ ions leave the cell against a concentration gradient but along an electrical gradient.
C)Na+ ions enter the cell along a concentration gradient and along an electrical gradient.
D)Na+ ions enter the cell along a concentration gradient but against an electrical gradient.
E)Cl- ions enter the cell along a concentration gradient and along an electrical gradient.

Question 49

Which of the following statements about the Na⁺-K⁺ pump is incorrect?

A)Phosphorylation of the pump must occur before K+ can attach to its binding site.
B)It has ATP synthase activity.
C)It helps decrease Na+ and K+ concentration gradients across the plasma membrane.
D)It regulates cell volume by controlling the concentration of solutes inside the cell.
E)Its action is important for secondary active transport.

Question 50

Anionic intracellular proteins (A⁻) cannot pass through membrane carriers because A⁻ proteins

A)are charged
B)they can only pass through channels
C)are in about the same concentration in the cytosol and ECF
D)too large
E)are synthesized outside the cell, and carriers only transport them into the cell

Question 51

A Ca²⁺ pump in the plasma membrane

A)pumps Ca+2 into the cell
B)is a secondary active transport carrier
C)is an ATPase
D)is a symporter
E)allows Ca+2 to diffuse into the cell

Question 52

What is primarily responsible for the development of a resting membrane potential?

A)More diffusion and active transport of cations out of the cell than into the cell
B)Pumping 2 K+ ions out of the cell for every three Na+ ions pumped into the cell
C)More K+ ions diffusing into the cell than there are Na+ ions diffusing out of the cell
D)More anions diffusing into the cell than are diffusing out of the cell
E)None of the above are primarily responsible.

Question 53

With secondary active transport, the movement of

A)H+ out of a cell by antiport is downhill
B)amino acids into the cell by symport is uphill
C)glucose into a cell by cotransport is downhill
D)H+ is in the same direction as the movement of Na+
E)glucose is in the opposite direction as the movement of Na+

Question 54

If a human cell is placed into solution X, containing water and a nonpenetrating solute, then

A)water will diffuse into solution X until the cytosol and solution X are isotonic.
B)water will diffuse across the membrane until a state of equilibrium is established.
C)water will diffuse into the cell until stopped by an opposing hydrostatic pressure in the cytosol.
D)neither the cell nor solution X will experience a net gain of water.
E)it is not possible to predict what will happen.

Question 55

Which statement(s) is/are true about membrane potentials?

A)They are differences in electrical charge on opposite sides of a membrane
B)They are measured in millivolts, with the sign designating the charge on the outside
C)They exist because the ECF as a whole is positively-charged and the cytosol as a whole is negatively charged
D)They are always positive during the resting state
E)All of the above statements are true.

Question 56

Pinocytosis is a form of

A)active transport
B)cytokinesis
C)endocytosis
D)exocytosis
E)hemolysis

Question 57

The resting membrane potential of a typical nerve cell is ____ mV.

A)-60
B)+70
C)-90
D)-50
E)-70

Question 58

Which statement(s) would be true about the resting membrane potential?

A)It is closer to the equilibrium potential for Na+ than to the equilibrium potential for K+
B)It is closer to the equilibrium potential for K+ than to the equilibrium potential for Na+
C)It is about the same as the equilibrium potential for Cl-
D)Only a and b are true
E)Only b and c

Question 59

Exocytosis of secretory products from neuron terminals is triggered by the entry of ____ into the ____.

A)K+; cytosol
B)Na+; ECF
C)Ca₂₊; cytosol
D)ATP; plasma membrane
E)A-; ECF

Question 60

Solution 1 has a higher concentration of NaCl than solution 2.A membrane permeable only to Na⁺ and water separates the two membranes.Which of the following is true?

A)Na+ will diffuse into solution 2 until the two solutions become isotonic.
B)Solution 2 has a higher osmolarity.
C)A membrane potential will develop, with the negative side being in solution 1.
D)Solution 2 will gain water from solution 1.
E)Eventually, solution 2 will contain only Na+ and solution 1 will contain only Cl-

Question 61

What might account for a net movement of water from solution X into solution Y?

A)Solution X has a higher osmolarity than the cell.
B)Solution X has more milliosmoles of solute per liter than the cell.
C)Solution X has a higher hydrostatic pressure than solution Y
D)All of the above
E)Only a and b

Question 62

Which pairing has the most closely related items?

A)Tight junction, connexon
B)Gap junction, cadherin
C)Tight junction, kiss site
D)Gap junction, plaque
E)Desmosome, claudin

Question 63

Which intercellular connections force transcellular transport to occur.

A)Tight junctions
B)Desmosomes
C)Gap junctions
D)Both A and B
E)Both B and C

Question 64

Which one of the following requires the cell to expend energy?

A)ECF moving into a cell via pinocytosis
B)Glucose moving through a facilitated diffusion carrier
C)K+ ions moving out of a cell
D)Water moving through an aquaporin
E)Na+ ions moving through a leak channel

Question 65

Which of the following is not a function of membrane proteins?

A)Transport of polar molecules
B)Transport of H+ into the cell
C)Binding sites for vesicles
D)Cell recognition
E)Passageway for water molecules

Question 66

Which of the following is most closely related to transcellular transport?

A)Cadherins
B)Claudins
C)Peripheral proteins
D)Connexons
E)Cadherins

Question 67

Individual proteins typically pass through the plasma membrane by

A)primary active transport
B)symport
C)vesicular transport
D)secondary active transport
E)facilitated diffusion

Question 68

Movement of a substance up a gradient can occur through

A)the GLUT carrier
B)a facilitated diffusion carrier
C)an aquaporin
D)the SGLT carrier
E)a membrane channel

Question 69

Which statement about the rate of diffusion through a lipid bilayer membrane is incorrect?

A)Smaller substances diffuse faster than larger substances.
B)Lipid-soluble items diffuse faster than water-soluble items.
C)Items diffuse through narrow membranes faster than through thick membranes.
D)The presence of microvilli decreases the rate of diffusion.
E)A greater concentration gradient causes faster diffusion.

Question 70

All of the following transport certain substances from regions of high concentration to low concentration except

A)carriers
B)facilitated diffusion
C)SGLT
D)GLUT
E)Ca₂₊ pump

Question 71

Which of the following allows a membrane potential to be measured directly by taking into account relative permeabilities and gradients for all permeable ions?

A)Goldman-Hokgkin-Katz equation
B)Nernst equation
C)Fick's equation
D)All of the above
E)Only a and c

Question 72

Which statement is false?

A)Binding of Na+ to the SGLT carrier increases the carrier's affinity for ATP.
B)The release of Na+ from the SGLT carrier increases the carrier's affinity for glucose.
C)Glucose enters the luminal side of an intestinal cell through a GLUT carrier.
D)The GLUT carrier is a symporter.
E)The SGLT carrier is a symporter.

Question 73

Which answer is true about NET water movement between two solutions that are separated by a semipermeable membrane.

A)It will always be toward the solution with the lower osmotic pressure.
B)It might be toward the solution with the lower osmotic pressure.
C)It will always be toward the solution with the lower hydrostatic pressure.
D)It might be toward both solutions at the same time.
E)None of the above statements are true.

Question 74

Which statement is most likely to be true about a crenating cell?

A)It is surrounded by a hypotonic ECF.
B)It has a lower osmotic pressure than the ECF
C)It has a higher concentration of solutes than the ECF.
D)It is experiencing a net gain of water.
E)It is surrounded by a solution having a solute concentration less than 300 mOsm/L.

Question 75

If solution A has a higher concentration of solute particles than solution B and if these solutions are separated by a semipermeable membrane, then there will be a net movement of water

A)into solution B since B has a lower osmotic pressure than solution A
B)into solution B since B will have a higher hydrostatic pressure than solution A
C)into solution B since the osmolarity of B is less than that in solution A
D)into solution A since B has a higher osmotic pressure than solution A
E)into solution A since A has a lower concentration of water than solution B

Question 76

Which pairing shows the least-related items?

A)Na+-K+ pump, transmembrane protein
B)Facilitated diffusion carrier, integral protein
C)Aquaporin, peripheral protein
D)Calcium pump, integral protein
E)Na+-K+ pump, integral protein

Question 77

Which of the following cannot pass through a plasma membrane by primary active transport?

A)Sodium
B)Glucose
C)Calcium
D)Potassium
E)Hydrogen ions

Question 78

Glucose may pass through a plasma membrane using all of the following methods EXCEPT

A)cotransport
B)secondary active transport
C)facilitated diffusion
D)simple diffusion
E)symport

Question 79

A substance does not move down a concentration gradient through

A)a symporter
B)an antiporter
C)a primary active transporter
D)a secondary active transporter
E)facilitated diffusion carrier

Question 80

Opening a sodium channel when the membrane potential is at equilibrium will cause

A)the membrane potential to become more negative
B)the membrane potential to decrease
C)the inside border of the membrane to become more negative
D)the outside border of the membrane to become more positive
E)all of the above reactions