Bsc1010 Chapter 5

Front 1

1.  Which of the following organisms is likely to contain biomembranes?  
A.  plants
B.  animals
C.  prokaryotes
D.  plants and animals
E.  All living organisms contain biomembranes.

Back 1

E. All living organisms contain biomembranes.

Front 2

2.  Cellular membranes are  
A.  fluid.
B.  solely composed of lipids.
C.  composed of a single layer of amphipathic molecules.
D.  selective to the transport of gases and small molecules only.
E.  characteristic of eukaryotes, but not prokaryotes.

Back 2

A. fluid.

Front 3

3.  Which of the following is the major lipid found in membranes?  
A.  steroids
B.  cholesterol
C.  triglycerides
D.  phospholipids
E.  saturated fatty acids

Back 3

D. phospholipids

Front 4

4.  Which of the following is NOT true of the plasma membrane?  
A.  It is composed of an extracellular and intracellular layer of phospholipids.
B.  The extracellular and intracellular layers or leaflets are highly symmetrical.
C.  The membrane contains peripheral proteins.
D.  Integral proteins span through the membrane.
E.  The membrane contains glycolipids and glycoproteins.

Back 4

B. The extracellular and intracellular layers or leaflets are highly symmetrical.

Front 5

5.  Which of the following statements about plasma membranes is INCORRECT?  
A.  They are composed of phospholipids.
B.  They have both integral and peripheral proteins.
C.  They are relatively rigid structures.
D.  They are composed of two leaflets of phospholipids.
E.  They function to separate the extracellular and intracellular environment.

Back 5

C. They are relatively rigid structures.

Front 6

6.  Scientists unearth a Wooly Mammoth from the Siberian Ice Sheath and discover that a eukaryotic "amoeba"-like cell is still alive. Which component of the cell membrane might contribute to maintaining the fluidity of plasma membranes under freezing conditions?  
A.  peripheral proteins
B.  high levels of long fatty acyl tails within the lipid bilayer
C.  high levels of unsaturated fatty acyl tails within the lipid bilayer
D.  absence of cholesterol
E.  high levels of saturated fatty acyl tails within the lipid bilayer

Back 6

C. high levels of unsaturated fatty acyl tails within the lipid bilayer

Front 7

7.  Which of the following statements is CORRECT about biomembranes?  
A.  The phospholipid tails interact with water.
B.  The phospholipid head groups are repelled by water.
C.  Electron microscopy indicates the membrane looks like train tracks with two light lines of lipids separated by a dark line containing proteins.
D.  The membrane is composed of two protein layers separated by a lipid layer.
E.  Membrane proteins are globular, and some span the phospholipid bilayer and project from both sides of the membrane.

Back 7

E. Membrane proteins are globular, and some span the phospholipid bilayer and project from both sides of the membrane.

Front 8

A scientist produces an artificial membrane from phospholipids and notices that oxygen, but not glucose readily moves through the membrane. What might account for the inability of glucose to move through the artificial membrane?  
A.  The artificial membrane lacked a protein needed for glucose transport.
B.  The artificial membrane lacked the appropriate types of phospholipids for glucose transport.
C.  Oxygen readily passes through the membrane, so glucose should have as well.
D.  The membrane lacked an adequate amount of amphipathic molecules for glucose transport.
E.  Thermodynamics does not allow glucose to pass through membranes produced either artificially or from living organisms.

Back 8

A. The artificial membrane lacked a protein needed for glucose transport.

Front 9

9.  Which of the following is NOT a component of plasma membranes?  
A.  glycosylated proteins
B.  phospholipids
C.  glycolipids
D.  glycosylated nucleic acids
E.  cholesterol

Back 9

D. glycosylated nucleic acids

Front 10

10.  Around what percentage of all genes encode membrane proteins?  
A.  0%
B.  10%
C.  25%
D.  50%
E.  75%

Back 10

C. 25%

Front 11

11.  Which of the following is NOT a function of cellular membranes?  
A.  selective uptake and export of ions and molecules
B.  cell compartmentalization
C.  cell signaling
D.  maintenance of cell shape
E.  cell adhesion

Back 11

D. maintenance of cell shape

Front 12

12.  Which of the following statements is TRUE of membrane phospholipids?  
A.  The hydrophilic head groups face the interior portion of the membrane.
B.  The hydrophobic tail groups face the exterior portion of the membrane.
C.  They spontaneously flip-flop from one side of the membrane to the other.
D.  They freely move laterally within the membrane.
E.  They rarely flip-flop across or move laterally within the membrane.

Back 12

D. They freely move laterally within the membrane.

Front 13

13.  Phospholipids and ________ are the major components of cell membranes.  
A.  glycolipids
B.  cholesterol
C.  glucose transporters
D.  glycocalyx
E.  proteins

Back 13

E. proteins

Front 14

14.  Cell surface molecules are labeled with a fluorescent tag and then a portion of them are bleached with a laser beam. What would one observe after the cell is incubated for a few minutes?  
A.  The bleached molecules would disappear into the cell.
B.  The bleached molecules would diffuse laterally through the membrane and intermix with unbleached molecules.
C.  The bleached molecules would remain in the spot where bleaching occurred.
D.  All the bleached molecules would flip-flop across the cell membrane.
E.  All of the choices are correct.

Back 14

B. The bleached molecules would diffuse laterally through the membrane and intermix with unbleached molecules.

Front 15

15.  The following affect membrane fluidity EXCEPT
A.  glycoprotein composition.
B.  cholesterol.
C.  phospholipid composition.
D.  the length of the phospholipid fatty acyl tail.
E.  the relative amounts of phospholipids containing saturated or unsaturated fatty acyl tails.

Back 15

A. glycoprotein composition.

Front 16

16.  Which of the following is TRUE of phospholipids that flip-flop across the lipid bilayer?  
A.  The process requires energy.
B.  The process occurs spontaneously, requiring no energy.
C.  The process requires an enzyme called flippase.
D.  The process requires energy and the flippase enzyme.
E.  The process occurs spontaneously and requires the flippase enzyme.

Back 16

D. The process requires energy and the flippase enzyme.

Front 17

17.  Cellular membranes are mosaic and  
A.  fluid.
B.  rigid.
C.  symmetrical.
D.  highly permeable to large molecules.
E.  All of the choices are correct.

Back 17

A. fluid.

Front 18

18.  How might a plant cell compensate for the excessive membrane fluidity that occurs during prolonged exposures to elevated temperature?  
A.  Reduce membrane cholesterol content.
B.  Alter the lipid composition to have longer fatty acyl tails and fewer double bonds.
C.  Alter the lipid composition to have shorter fatty acyl tails and more double bonds.
D.  Alter the lipid composition to have shorter and more unsaturated fatty acyl tails.
E.  Reduce cholesterol content and alter the lipid composition to have shorter fatty acyl tails.

Back 18

B. Alter the lipid composition to have longer fatty acyl tails and fewer double bonds.

Front 19

19.  Glycosylated proteins and lipids within the plasma membrane are important for  
A.  cell recognition.
B.  cell protection.
C.  cell energy storage.
D.  cell recognition and protection.
E.  cell protection and energy storage.

Back 19

D. cell recognition and protection.

Front 20

20.  Which of the following is important for allowing large, charged molecules to pass through the membrane?  
A.  peripheral proteins
B.  cholesterol
C.  glycosylated lipids
D.  transmembrane proteins
E.  carbohydrate channels

Back 20

D. transmembrane proteins

Front 21

21.  Placing celery sticks in fresh water will make them more turgid and harder. This is because  
A.  the celery is hypotonic to fresh water.
B.  the celery is hypertonic to fresh water.
C.  the celery is isotonic to fresh water.
D.  water moves from the celery sticks into fresh water.
E.  None of the choices are correct.

Back 21

B. the celery is hypertonic to fresh water.

Front 22

22.  Of the following molecules, which passes through a lipid bilayer most readily?  
A.  carbon dioxide
B.  glucose
C.  K+
D.  arginine
E.  RNA

Back 22

A. carbon dioxide

Front 23

23.  Which of the following molecules would you predict moves through a lipid bilayer most rapidly?  
A.  C6H12O6
B.  CH3OH
C.  C2H5OH
D.  C4H10
E.  NH2SO2CH3

Back 23

D. C4H10

Front 24

24.  Animal cells are permeable to water and urea but NOT to sucrose. The inside of a cell contains 1 M sucrose and 1 M urea and the outside 1 M sucrose and 2 M urea. The solution inside with respect to outside the cell is  
A.  hypotonic.
B.  turgid.
C.  isotonic.
D.  saturated.
E.  hypertonic.

Back 24

A. hypotonic.

Front 25

25.  Animal cells are permeable to water and urea but NOT to sucrose. Initially, the inside of a cell contains 1 M sucrose and 1 M urea and the outside 1 M sucrose and 2 M urea. After the system reaches equilibrium, what changes are observed?  
A.  The molarity of urea would be higher outside than inside the cell.
B.  The molarity of sucrose would be similar inside and outside the cell.
C.  Water would move out of the cell causing the cell to shrivel.
D.  The molarity of urea would be higher outside the cell and the molarity of sucrose would be similar inside and outside the cell.
E.  The molarity of sucrose would be similar inside and outside the cell and water would move out of the cell causing the cell to shrivel.

Back 25

E. The molarity of sucrose would be similar inside and outside the cell and water would move out of the cell causing the cell to shrivel.

Front 26

26.  Which of the following statements is CORRECT about active transport?  
A.  It requires energy.
B.  It is an active process in which molecules move from a region of lower concentration to one of higher concentration.
C.  It requires integral proteins.
D.  It is necessary to maintain solute gradients across a membrane.
E.  All of the choices are correct.

Back 26

E. All of the choices are correct.

Front 27

27.  Which of the following is NOT true of passive diffusion?  
A.  Passive diffusion is the process by which molecules move from an area of high concentration to an area of low concentration.
B.  Passive diffusion is a spontaneous process.
C.  Passive diffusion requires the presence of a transmembrane protein.
D.  Passive diffusion will occur so long as the membrane is freely permeable to the solute.
E.  Passive diffusion requires no energy.

Back 27

C. Passive diffusion requires the presence of a transmembrane protein.

Front 28

28.  Following a meal glucose must move from the gut lumen where there is a high glucose concentration into the intestinal cell where there is a relatively low level of glucose. This movement is called  
A.  passive diffusion.
B.  facilitated diffusion.
C.  active transport.
D.  endocytosis.
E.  exocytosis.

Back 28

B. facilitated diffusion.

Front 29

29.  The pressure required to stop water from moving across the membrane by osmosis is called  
A.  transport pressure.
B.  crenation pressure.
C.  atmospheric pressure.
D.  osmotic pressure.
E.  mechanical pressure.

Back 29

D. osmotic pressure.

Front 30

30.  Water diffuses through certain organs such as the kidneys and bladder much faster than would occur by passive diffusion through a lipid bilayer alone. What accounts for this more rapid rate of water transport in these organs?  
A.  The composition of lipids changes to promote water transport.
B.  Presence of aquaporin channels for facilitated diffusion of water.
C.  Presence of a water pump.
D.  Presence of an ATP-driven enzyme for water transport.
E.  The presence of molecules that bind water and change its membrane permeability properties.

Back 30

B. Presence of aquaporin channels for facilitated diffusion of water.

Front 31

31.  The movement of sucrose and H+ into the cell by a common membrane protein reflects transport through a  
A.  voltage-gated channel.
B.  mechanosensitive channel.
C.  uniporter.
D.  symporter.
E.  antiporter.

Back 31

D. symporter.

Front 32

32.  The statements about transport of Ca2+ from the cytosol (low Ca2+ concentration) into the endoplasmic reticulum (high Ca2+ concentration) are true EXCEPT which of the following?  
A.  Calcium movement involves the use of a pump.
B.  Calcium movement involves active transport.
C.  Calcium movement occurs by facilitated diffusion using a transporter protein.
D.  Calcium movement requires energy.
E.  Calcium movement occurs through a transmembrane protein.

Back 32

C. Calcium movement occurs by facilitated diffusion using a transporter protein.

Front 33

33.  Acetylcholine binds this membrane protein, which subsequently opens to allow sodium to enter the cell. Acetylcholine exerts its effect on what type of transport protein?  
A.  ligand-gated channel
B.  voltage-gated channel
C.  mechanosensitive-gated channels
D.  regulatory protein-gated channels
E.  stretch-sensitive gated channels

Back 33

A. ligand-gated channel

Front 34

34.  Sodium concentrations are higher outside and glucose concentrations are higher inside the cell. Using the same membrane protein for Na+ and glucose transport, what is it called when a Na+ electrochemical gradient is used to drive glucose transport into the cell against its concentration gradient?  
A.  primary active transport
B.  secondary active transport
C.  primary facilitated diffusion
D.  secondary facilitated diffusion
E.  passive diffusion

Back 34

B. secondary active transport

Front 35

35.  ________ bind two or more ions or molecules and transport them in opposite directions across a membrane.  
A.  uniporters
B.  symporters
C.  antiporters
D.  dual transporters
E.  channel pumps

Back 35

C. antiporters

Front 36

36.  Which of the following statement about the plasma membrane Na+/K+-ATPase pump is INCORRECT?  
A.  It is used to generate sodium and potassium gradients across the membrane.
B.  It is an electrogenic pump.
C.  It is a pump for active transport of K+ out of the cell and Na+ into the cell.
D.  It is a pump for active transport of K+ into the cell and Na+ out of the cell.
E.  It is a pump that utilizes energy from ATP.

Back 36

C. It is a pump for active transport of K+ out of the cell and Na+ into the cell.

Front 37

37.  The release of insulin from pancreatic cells occurs by  
A.  endocytosis.
B.  pinocytosis.
C.  phagocytosis.
D.  exocytosis.
E.  receptor-mediated endocytosis.

Back 37

D. exocytosis.

Front 38

38.  Which of the following best describes the selective uptake of a specific cargo molecule into the cell through receptor binding and aggregation?  
A.  pinocytosis
B.  receptor-mediated endocytosis
C.  autophagocytosis
D.  phagocytosis
E.  receptor-mediated exocytosis

Back 38

B. receptor-mediated endocytosis

Front 39

39.  Plant cell membranes contain cholesterol.  

Back 39

FALSE

Front 40

40.  Membrane proteins are attached to or embedded in the phospholipid bilayer.  

Back 40

TRUE

Front 41

41.  The presence of integral proteins allows membranes to be selectively permeable to certain molecules.  

Back 41

TRUE

Front 42

42.  Freeze fracture electron microscopy allows one to observe the two-dimensional cross section of membrane proteins.  

Back 42

FALSE

Front 43

43.  The current model that best describes biomembranes is the Rigid Mosaic Model.  

Back 43

FALSE

Front 44

44.  Diffusion is the movement of a molecule from an area of high to low concentration.  

Back 44

TRUE

Front 45

45.  Osmosis describes the movement of water from an area of high to low solute concentration.  

Back 45

FALSE

Front 46

46.  Movement of molecules down their concentration gradient can drive the movement of a different molecule against its concentration gradient.  

Back 46

TRUE

Front 47

47.  Facilitated diffusion is required for the movement of Na+ out of the cell.  

Back 47

FALSE

Front 48

48.  The Na+/K+-ATPase pump is a ligand-gated ion channel.  

Back 48

FALSE

Front 49

49.  A macrophage (immune cell) consuming a bacteria is best described as phagocytosis.  

Back 49

TRUE

Front 50

50.  Ion gradients across the membrane drive numerous cellular functions.  

Back 50

TRUE