Chapter 5

Front 1

1. The lipid layer that forms the foundation of cell membranes is primarily composed of molecules called __________.
A. phospholipids
B. fats
C. proteins
D. carbohydrates

Back 1

A. phospholipids

Front 2

2. While water continually orients phospholipids into a lipid bilayer, it does not fix the lipids permanently into position. Thus, the bilayer is considered to be _______.
A. static
B. fluid
C. fluctuating
D. charged

Back 2

B. fluid

Front 3

3. What is the net movement of substances to regions of lower concentration called?
A. Osmosis
B. Active transport
C. Facilitation
D. Diffusion

Back 3

D. Diffusion

Front 4

4. Osmosis is the diffusion of water across a membrane in response to the concentration of one or more of the ______.
A. solutes
B. membranes
C. compartments
D. cells

Back 4

A. solutes

Front 5

5. Which type of proteins is embedded in the cell membrane in both active transport and facilitated transport?
A. carrier
B. cytoskeletal
C. structural
D. targeted

Back 5

A. carrier

Front 6

6. Osmosis occurs as water can cross the lipid bilayer through specialized channels for water movement called ________________.
A. proteins
B. transmembrane carbohydrates
C. membrane pores
D. aquaporins

Back 6

D. aquaporins

Front 7

7. The plasma membrane is a thin sheet of lipid embedded with
A. proteins.
B. carbohydrates.
C. polymers.
D. nucleotides.
E. sodium and potassium ions.

Back 7

A. proteins.

Front 8

8. Membrane proteins are not very soluble in water, because they possess long stretches of non-polar amino acids that are
A. too long to interact with the water molecules.
B. hydrophobic.
C. are transmembranal.
D. hydrophilic.
E. used as transport channels.

Back 8

B. hydrophobic.

Front 9

9. If a cell has the same concentration of dissolved molecules as its outside environment, the cell's condition is referred to as being
A. isotonic.
B. hypertonic.
C. hypotonic.
D. hydrophobic.
E. hydrophilic.

Back 9

A. isotonic.

Front 10

10. A type of transport of a solute across a membrane, up its concentration gradient, using protein carriers driven by the expenditure of chemical energy is known as
A. osmosis.
B. diffusion.
C. facilitated transport.
D. active transport.
E. exocytosis.

Back 10

D. active transport.

Front 11

12. How are the tails and heads of membrane phospholipids oriented in their environment?
A. The hydrophobic heads are oriented towards each other and the hydrophillic tails are oriented towards the extracellular fluid and the intracellular fluid.
B. The hydrophillic tails are oriented towards each other and the hydrophobic heads are oriented towards the extracellular fluid and the intracellular fluid.
C. The hydrophobic tails are oriented towards each other and the hydrophillic heads are oriented towards the extracellular fluid and the intracellular fluid.
D. The hydrophillic heads are oriented towards each other and the hydrophobic tails are oriented towards the extracellular fluid and the intracellular fluid.

Back 11

C. The hydrophobic tails are oriented towards each other and the hydrophillic heads are oriented towards the extracellular fluid and the intracellular fluid.

Front 12

13. The fluid nature of the membranes is attributed to a lateral movement of
A. protein channels.
B. phospholipid molecules.
C. antigen molecules.
D. pumps such as the proton pump.
E. the entire lipid bilayer.

Back 12

B. phospholipid molecules.

Front 13

14. On the outer surface of the plasma membrane there are marker molecules that identify the cell type. Often these molecules are
A. ATP.
B. amino acids.
C. nucleotides.
D. carbohydrate chains.
E. inorganic ions.

Back 13

D. carbohydrate chains.

Front 14

15. Which of the following protein classes are not found as membrane proteins?
A. transport channels
B. hormones
C. receptors
D. enzymes
E. identity markers

Back 14

B. hormones

Front 15

16. The part of a membrane protein that extends through the phospholipid bilayer is primarily composed of amino acids that are
A. highly polar.
B. negatively charged.
C. non-polar.
D. positively charged.
E. water soluble.

Back 15

C. non-polar.

Front 16

17. Red blood cells are bi-concave. Their shape is determined by interior proteins anchored to the membrane termed
A. clathrins.
B. phospholipids.
C. cytoskeleton.
D. spectrins.
E. actin filaments.

Back 16

D. spectrins.

Front 17

18. The movement of substances to regions of lower concentration is called
A. active transport.
B. diffusion.
C. pinocytosis.
D. pumping.
E. exocytosis.

Back 17

B. diffusion.

Front 18

19. If two solutions have unequal concentrations of a solute, the solution with the lower concentration is called
A. isotonic.
B. hypertonic.
C. hypotonic.
D. osmosis.

Back 18

C. hypotonic.

Front 19

20. In bacteria, fungi, and plants the high internal pressure generated by osmosis is counteracted by the mechanical strength of their
A. plasma membranes.
B. organelles.
C. cytoskeletons.
D. cell walls.

Back 19

D. cell walls.

Front 20

21. The actual transport of protons by the proton pump is mediated by a transmembrane protein which undergoes a change in its
A. conformation.
B. amino acid sequence.
C. net charge.
D. solubility.
E. immunity.

Back 20

A. conformation.

Front 21

22. The process often referred to as "cellular eating" is
A. osmosis.
B. pinocytosis.
C. phagocytosis.
D. diffusion.
E. active transport.

Back 21

C. phagocytosis.

Front 22

23. Carrier-mediated transport is also called
A. facilitated diffusion.
B. active transport.
C. exocytosis.
D. endocytosis.
E. phagocytosis.

Back 22

A. facilitated diffusion.

Front 23

24. Osmosis can only occur if water travels through the
A. cell wall.
B. semi-permeable membrane.
C. vacuole.
D. ER.
E. cytoskeleton.

Back 23

B. semi-permeable membrane.

Front 24

25. Organisms with a cell wall cannot carry out
A. exocytosis.
B. active transport.
C. osmosis.
D. diffusion.
E. endocytosis.

Back 24

E. endocytosis.

Front 25

26. The type of movement of molecules that is specific and passive, and which becomes saturated if all of the protein carriers are in use is
A. exocytosis.
B. facilitated diffusion.
C. active transport.
D. endocytosis.
E. osmosis.

Back 25

B. facilitated diffusion.

Front 26

27. The type of movement that is specific and requires carrier molecules and energy is
A. exocytosis.
B. facilitated diffusion.
C. active transport.
D. endocytosis.
E. osmosis.

Back 26

C. active transport.

Front 27

28. In a single sodium-potassium pump cycle, ATP is used with the result that
A. 3 sodium ions leave and 2 potassium ions enter.
B. 2 sodium ion enters and 1 potassium ion leaves.
C. 2 sodium ion leaves and 1 potassium ion enters.
D. 3 sodium ions enter and 2 potassium ions leave.
E. sodium and potassium ions enter and water leaves.

Back 27

A. 3 sodium ions leave and 2 potassium ions enter.

Front 28

29. The accumulation of amino acids and sugars in animal cells can occur through
A. ATP pumps.
B. sodium-potassium pumps.
C. glucose pumps.
D. coupled transport.
E. proton pumps.

Back 28

D. coupled transport.

Front 29

30. Cholesterol functions in the plasma membrane to
A. transport ions.
B. serve as an energy molecule.
C. maintain fluidity.
D. mediate steroid action.
E. maintain hypertension.

Back 29

C. maintain fluidity.

Front 30

31. A phospholipid molecule has a polar and a nonpolar end. Because of this, water molecules form
A. polar bonds with the nonpolar end of the phospholipid molecule.
B. polar bonds with the polar end of the phospholipid molecule.
C. hydrogen bonds with the nonpolar end of the phospholipid molecule.
D. hydrogen bonds with the polar end of the phospholipid molecule.
E. covalent bonds with the nonpolar end of the phospholipid molecule.

Back 30

D. hydrogen bonds with the polar end of the phospholipid molecule.

Front 31

32. The fluid mosaic model proposed by Singer and Nicolson in 1972 explained that
A. the cell membrane was composed of lipids and proteins.
B. the cell membrane was composed of a phospholipid bilayer between two layers of globular proteins.
C. the cell membrane was composed of a phospholipid bilayer with globular proteins actually inserted into the bilayer.
D. the cell membrane was composed of a phospholipid bilayer but the polar ends of the phospholipid molecules were reversed.

Back 31

C. the cell membrane was composed of a phospholipid bilayer with globular proteins actually inserted into the bilayer.

Front 32

33. Membrane proteins serve many functions. One of the functions is transportation of substances across the membrane. If a cell biologist placed cells into an environment in which a chemical has been added that blocks the function of only carrier proteins, the process that will be affected is
A. active transport.
B. osmosis.
C. simple diffusion.
D. phagocytosis.
E. pinocytosis.

Back 32

A. active transport.

Front 33

34. For the process of diffusion to occur, molecules must
A. move from areas of high concentration to areas of lesser concentration until an equilibrium is reached.
B. move from areas of low concentration to areas of higher concentration until an equilibrium is reached.
C. remain stationary until their molecular motion allows for an equilibrium to be reached.
D. move from areas of high concentration to areas of lesser concentration until facilitated transport can assist the molecular equilibrium.
E. move from areas of high concentration to areas of lesser concentration until an equilibrium is reached by active transport.

Back 33

A. move from areas of high concentration to areas of lesser concentration until an equilibrium is reached.

Front 34

35. Facilitated diffusion is an important method for cells in obtaining necessary molecules and removing other ones. Requirements for facilitated diffusion include
A. The carrier molecule must be specific to the molecule that is transported. The direction of movement is always with the concentration gradient, never against the gradient.
B. The carrier molecule is nonspecific to the molecule that is transported. The direction of movement is always with the concentration gradient, never against the gradient.
C. The carrier molecule is nonspecific to the molecule that is transported. The direction of movement is always against the concentration gradient, never with the gradient.
D. The carrier molecule must be specific to the molecule that is transported and an ATP molecule must be attached to the specific carrier. The direction of movement is always against the concentration gradient, never with the gradient.

Back 34

A. The carrier molecule must be specific to the molecule that is transported. The direction of movement is always with the concentration gradient, never against the gradient.

Front 35

36. A research laboratory is attempting to collect the content of human red blood cells. The type of solution researchers should use to cause blood cell to lyse (burst) would be
A. hyperosmotic.
B. isosmotic.
C. hypoosmotic.
D. osmotic.

Back 35

C. hypoosmotic.

Front 36

37. One day during the summer you and some friends make ice cream using an electric ice cream maker. A few days later you notice a yellow circle of dead grass where the ice cream freezer had been placed. What happened?
A. The ice and salt mixture that spilled out when the freezer was moved froze the grass.
B. The ice and salt mixture was isosmotic to the grass cells and caused the yellow circle of dead grass.
C. The ice and salt mixture was hyperosmotic to the grass cells and caused the yellow circle of dead grass.
D. The ice and salt mixture was hypoosmotic to the grass cells and caused the yellow circle of dead grass.

Back 36

C. The ice and salt mixture was hyperosmotic to the grass cells and caused the yellow circle of dead grass.

Front 37

38. What is the main component of an animal cell membrane?
A. phospholipids
B. polynucleotides
C. aquaporins
D. glycolipids
E. cholesterol

Back 37

A. phospholipids

Front 38

39. A scientist performs an experiment in which they create an artificial cell with a selectively permeable membrane through which only water can pass. They inject a 5M solution of glucose into the cell and then place the cell into a beaker of water. After an hour, what effect do you expect to observe?
A. Water moves out of the cell
B. Glucose moves out of the cell
C. No net change in cell weight
D. Water moves into the cell
E. Glucose moves into the cell

Back 38

D. Water moves into the cell

Front 39

40. A scientist performs an experiment in which they create an artificial cell with a selectively permeable membrane through which only water can pass. They inject a 5M solution of glucose into the cell and then place the cell into a beaker containing 10M glucose. What effect do you expect to observe?
A. Water moves out of the cell
B. Glucose moves out of the cell
C. No net change in cell weight
D. Water moves into the cell
E. Glucose moves into the cell

Back 39

A. Water moves out of the cell

Front 40

41. Turgor pressure is observed when a plant cells environment is ________________.
A. hypoosmotic
B. isosmotic
C. osmosis
D. hyperosmotic

Back 40

A. hypoosmotic

Front 41

42. What initiates the sodium-potassium pump?
A. Three sodium ions bind to the cytoplasmic side of the protein.
B. Three sodium ions are translocated out of the cell.
C. Phosphorylated pump has low affinity for sodium allowing sodium to leave and potassium to bind.
D. Two potassium ions are transported into the cell.
E. ATP binds to the protein which becomes phosphorylated (ADP is released).

Back 41

A. Three sodium ions bind to the cytoplasmic side of the protein.

Front 42

43. Cyclodextrins are a group of compounds capable of removing cholesterol from membranes. The effect most likely to have a large impact on cells as a result of cyclodextrin treatment would be
A. increased concentration of transmembrane proteins.
B. increased permeability of the membrane.
C. increased membrane fluidity at lower temperatures.
D. increased membrane fluidity at higher temperatures.
E. disruption of transmembrane protein structure.

Back 42

D. increased membrane fluidity at higher temperatures.

Front 43

44. Membrane fluidity is affected by
A. temperature, cholesterol, types of fatty acids.
B. size of molecules, polarity of molecules, temperature.
C. types of fatty acids, waters affinity for hydrogen bonding.
D. hyrophillic tails, hydrophobic heads, cholesterol.

Back 43

A. temperature, cholesterol, types of fatty acids.

Front 44

45. GABAA receptors play an essential role in neurotransmission in the central nervous system. In response to the appropriate signal, these receptors open up and allow Cl- to flow into the cell. Given this information, GABAA receptors can be classified as a
A. gated ion channel.
B. gated carrier protein.
C. symporter.
D. Cl- pump.

Back 44

A. gated ion channel.

Front 45

46. Protein X contains four transmembrane domains, a short N-terminus and a long C-terminus. Following protein synthesis, the N-terminus of the protein faces the lumen (the inside) of the ER. After protein X is transported to the cell surface via exocytosis, you would expect the N-terminus of protein X to be
A. extracellular.
B. cytoplasmic.
C. in the lumen.
D. in the lipid bilayer of the plasma membrane.

Back 45

A. extracellular.

Front 46

47. Incubation of cells at 20C blocks the release of proteins from the trans-Golgi. Under such conditions, you would expect to see
A. an increase in exocytosis.
B. a decrease in exocytosis.
C. an increase in endocytosis.
D. a decrease in endocytosis.

Back 46

B. a decrease in exocytosis.

Front 47

48. While eating lobster for dinner one night your friend asks what you think might happen if this marine invertebrate, which is normally isosmotic with respect to the surrounding seawater, were to be moved to a bay with a slightly lower salt concentration instead of being caught. You reply that, in order for the lobster to be isosmotic with respect to new environment,
A. it must move water in to match the solute concentration of its new environment.
B. it regulates its internal concentration of solutes to match that of its new environment.
C. it must move water out to match the solute concentration of its new environment.
D. it moves water in or out and regulates its internal concentration of water as needed.

Back 47

B. it regulates its internal concentration of solutes to match that of its new environment.

Front 48

49. If a cell has a normal osmotic pressure of 4500 mmHg and is placed into a solution with an osmotic pressure of 3500 mmHg, what will happen to the cell?
A. The cell will lose water and its osmotic pressure will decrease.
B. The cell will gain water and its osmotic pressure will decrease.
C.

The cell will gain water and its osmotic pressure will increase.

D. The cell will lose water and its osmotic pressure will increase.

Back 48

A. The cell will lose water and its osmotic pressure will decrease.

Front 49

50. In individuals with normal blood sugar levels, glucose is reabsorbed into the bloodstream in the kidney by members of the GLUT transporter family, which form an aqueous pore across the membrane through which glucose can move passively. As a result, no glucose is excreted in urine. However, in people with untreated diabetes mellitus, blood sugar levels are high and glucose is often present in the urine. What can explain this occurrence?
A. High blood glucose levels reverse the concentration gradient, allowing untransported glucose to be excreted in urine.
B. High blood glucose levels interfere with the coupled transport of water and glucose, allowing untransported glucose to be excreted in urine.
C. The GLUT transporters become saturated, allowing untransported glucose to be excreted in urine.
D. The GLUT transporters cannot hydrolyze ATP quickly enough for ATP to transport the extra glucose, thereby allowing untransported glucose to be excreted in urine.

Back 49

C. The GLUT transporters become saturated, allowing untransported glucose to be excreted in urine.

Front 50

52. Which mutations can interfere with the proper insertion of a protein in the plasma membrane?
A. A polar amino acid to a non-polar amino acid within a transmembrane domain
B. A non-polar amino acid to a polar amino acid within a transmembrane domain
C. A polar amino acid to a non-polar amino acid within a cytoplasmic domain
D. A non-polar amino acid to a polar amino acid within a cytoplasmic domain

Back 50

B. A non-polar amino acid to a polar amino acid within a transmembrane domain

Front 51

53. During neuronal signaling, a change in membrane potential will cause sodium channels to open and let Na+ ions diffuse down their concentration gradient into the cell. Which of the following helps establish the concentration gradient necessary for this process to occur?
A. Na+/K+ channel
B. voltage-gated Na+ channel
C. Na+ symporter
D. Na+/K+ pump

Back 51

D. Na+/K+ pump

Front 52

54. If you were to replace the phosphate group of a phospholipid with a fatty acid chain, you would have
A. glycerol.
B. a triglyceride.
C. cholesterol.
D. glycolipid.

Back 52

B. a triglyceride.

Front 53

55. If you were a very thirsty cell, which process would you use to take in some nutrients secreted by one of your neighbors?
A. Phagocytosis
B. Pinocytosis
C. Receptor-mediated endocytosis
D. Exocytosis

Back 53

B. Pinocytosis

Front 54

56. How can freeze-fracture be used to determine the orientation of a protein in a membrane?
A. Freeze-fracture allows a cell to be cleaved in between the lipid bilayer, splitting the plasma membrane into two layers.
B. Freeze-fracture allows a cell to be cleaved in such a way as to preserve the embedded proteins.
C. Freeze-fracture cuts the membrane in protein-sized components for viewing under an electron microscope.

Back 54

A. Freeze-fracture allows a cell to be cleaved in between the lipid bilayer, splitting the plasma membrane into two layers.

Front 55

57. Diapedesis is the movement of white blood cells through intact blood vessel walls into surrounding body tissue. It typically happens when an area of the body is injured or damaged, and an inflammation response is required. What role would you expect cell adhesion molecules to play in this process?
A. Cell adhesion molecules will allow the white blood cells to cling to one another to form a migrating clot.
B. Cell adhesion molecules help white blood cells adhere to the blood vessel wall so that they can migrate across the wall and infiltrate into the underlying tissue.
C. Cell adhesion molecules will allow the white blood cells to attach to the injured area so they become immobile.

Back 55

B. Cell adhesion molecules help white blood cells adhere to the blood vessel wall so that they can migrate across the wall and infiltrate into the underlying tissue.

Front 56

58. Membrane potential will affect the directional movement of
A. Glucose (C6H12O6)
B. Cholesterol
C. Potassium (K+)
D. Oxygen (O2)

Back 56

C. Potassium (K+)

Front 57

60. The rate of diffusion of molecules would be fastest in a cell with an
A. internal concentration of 45 percent and an external concentration of 50 percent in cold temperatures.
B. internal concentration of 50 percent and an external concentration of 12 percent in cold temperatures.
C. internal concentration of 50 percent and an external concentration of 12 percent in warm temperatures.
D. internal concentration of 40 percent and an external concentration of 35 percent in warm temperatures.

Back 57

C. internal concentration of 50 percent and an external concentration of 12 percent in warm temperatures.

Front 58

61. When the solute concentration of solution A is lower than the solute concentration of solution B, solution A is considered
A. hypertonic.
B. hypotonic.
C. isotonic.

Back 58

B. hypotonic.

Front 59

63. Tetrodotoxin is a potent poison, produced by some newts, pufferfish, and blue-ringed octopus that affects sodium transport involved with the voltage gates in neurons. A friend swimming in the Caribbean is pricked by a pufferfish and gets very sick. The most likely action the poison takes is
A. Mimicking a symporter and allowing sodium to rush out and potassium to rush in.
B. Mimicking an antiporter and allowing sodium to rush out.
C. Blocking an antiporter so sodium cannot rush in.
D. Blocking a symporter and keeping sodium from rushing in.

Back 59

C. Blocking an antiporter so sodium cannot rush in.

Front 60

64. An individual is constipated. They take magnesium salts to help loosen the stool. Why does this work?
A. Water moves from the intestines to the blood because the blood is hypertonic
B.

Water moves from the intestines to the blood because the blood is hypotonic.

C. Water moves from the blood to the intestines because the blood is hypertonic
D. Water moves from the blood to the intestines because the blood is hypotonic.

Back 60

D. Water moves from the blood to the intestines because the blood is hypotonic.

Front 61

65. Cholesterol is a structural component of cell membranes. Amount of cholesterol present can affect membrane stability and permeability. What is the role of cholesterol in a membrane?
A. A membrane that needs to be more rigid and more permeable, would have high cholesterol ratios.
B.

A membrane that needs to be rigid, such as a protective barrier, would have low cholesterol ratios.

C.

Membranes with low amounts of cholesterol are very stable and have increased permeability.

D. Membranes with high amounts of cholesterol are very stable and have decreased permeability.

Back 61

D. Membranes with high amounts of cholesterol are very stable and have decreased permeability.

Front 62

66. A dehydrated runner drinks a lot of water after a race. They rehydrate because
A. the stomach is hypotonic compared to the bloodstream.
B.

the bloodstream is hypotonic compared to the stomach.

C. the stomach and bloodstream are isotonic compared to each other.
D. water will diffuse from a low to high concentration.

Back 62

D. water will diffuse from a low to high concentration.

Front 63

67. To test for the presence of starch, iodine can be used. A positive reaction results in a black color. A dialysis bag filled with starch solution and secured on both ends is placed in iodine solution. After 30 minutes the dialysis bag appears black. Based on this information, what most accurately describes what happened?
A. Due to its size and polarity, starch was able to exit the dialysis bag and interact with the iodine solution.
B. Due to its size and polarity, iodine was able to enter the dialysis bag and interact with starch.

Back 63

B. Due to its size and polarity, iodine was able to enter the dialysis bag and interact with starch.

Front 64

68. A mixed solution of water and ions is exposed to a cell membrane and allowed to interact for an hour. Which would diffuse across a phospholipid bilayer fastest?
A. Water
B. NH4+
C. NH3
D. CH3COO-
E. Na+

Back 64

C. NH3

Front 65

69. The solution in the container is hypertonic to which egg?
A. Egg 1
B. Egg 2
C. Egg 3

Back 65

C. Egg 3

Front 66

70. Which egg is isotonic to the solution?
A. Egg 1
B. Egg 2
C. Egg 3

Back 66

B. Egg 2

Front 67

71. When compared to the solution, the egg that gained weight was ______.
A. Hypertonic
B. Hypotonic
C. Isotonic

Back 67

A. Hypertonic

Front 68

72. Carrier proteins are saturated at which point?
A. 1
B. 2
C. 3
D. 4

Back 68

D. 4

Front 69

73. The rate of diffusion will increase as
A. the number of glucose molecules decreases.
B. the number of glucose molecules increases.
C. temperature decreases.
D. pH rises.

Back 69

B. the number of glucose molecules increases.

Front 70

74. If Na+ levels were depleted in the extracellular fluid, rate of glucose movement would
A. increase.
B. decrease.
C. stay the same.

Back 70

B. decrease.

Front 71

76. A novice gardener notices that many plants in his garden look wilted. What osmotic solution would you suggest the novice gardener use to best return the plants to full health?
A. Place the plants in a 15% solute solution so water can be actively transported out of the plant cells.
B. Place the plants in a 5% solute solution so water can be actively transported out of the plant cells.
C. Place the plants in a 5% solute solution so water can diffuse into the plant cells.
D. Place the plants in a 15% solute solution so water can diffuse out of the plant cells.

Back 71

C. Place the plants in a 5% solute solution so water can diffuse into the plant cells.

Front 72

78. Matt is studying how the protein transferrin enters cells. He examines cells that have taken up transferrin, and finds clathrin-coated vesicles. What mechanism was used to take transferrin into the cell?
A. Phagocytosis
B. Pinocytosis
C. Exocytosis
D. Receptor-mediator endocytosis

Back 72

D. Receptor-mediator endocytosis