Deck 5: Biological Membranes

Question 1

Which statement about lipid bilayers is false ?

A) They are inflexible.
B) They are self-sealing.
C) They resist forming free ends.
D) They can fuse with other bilayers.
E) They spontaneously form closed vesicles.

Answer 1

A

Question 2

In a lipid bilayer, __________ fatty acid tails face each other within the bilayer and form a region that excludes water.

A) hypertonic
B) hyperosmotic
C) hypotonic
D) hydrophilic
E) hydrophobic

Answer 2

E

Question 3

A molecule that binds specifically to a receptor is called a ______________.

A) ligand
B) clathrin
C) endosome
D) macrophage
E) low-density lipoprotein

Answer 3

A

Question 4

Why can cholesterol act as a "fluidity buffer" in cell membranes?

A) It is slightly amphipathic because of the presence of one hydroxyl group.
B) It is slightly hydrophobic because of the presence of one hydroxyl group.
C) It is slightly hydrophobic because of the presence of one carboxyl group.
D) It is slightly amphipathic because of the presence of one carboxyl group.
E) It is slightly hydrophilic because of the presence of one hydrocarbon group.

Question 5

Peripheral proteins are linked to either surface of the plasma membrane by

A) covalent disulfide bonds.
B) associating with fatty acids through hydrophobic interactions.
C) associating with glycoproteins on the inner membrane surface.
D) bonding to integral proteins through noncovalent interactions.
E) embedding in only one side of the membrane.

Question 6

What type of molecule can rapidly cross a plasma membrane?

A) Large, polar molecules
B) Small, polar molecules
C) Large, hydrophilic molecules
D) Small, hydrophilic molecules
E) Small, hydrophobic molecules

Question 7

Which of the following is not a property of membranes?

A) They divide the cell into compartments.
B) They transmit signals between the environment and the interior of the cell.
C) They serve as surfaces for chemical reactions.
D) They adhere to and communicate with other cells.
E) They inhibit the passage of materials.

Question 8

Sodium-potassium pumps help to maintain a separation of charges across the plasma membrane, which is called the _________________.

A) symporter
B) macrophage
C) membrane potential
D) proton gradient
E) antiporter

Question 9

How do the phospholipids in vegetable oil differ from those of animal fat?

A) The fatty acid tails bend.
B) The fatty acid tails lack double bonds.
C) The fatty acid tails are a chain of saturated fats.
D) The fatty acid tails solidify at room temperature.
E) The fatty acid tails interact via van der Waals forces.

Question 10

What facilitates the rapid transport of water through the plasma membrane?

A) Osmosis
B) Uniporters
C) Aquaporins
D) Channel proteins
E) ABC transporters

Question 11

Mammalian red blood cells contain which type of membrane?

A) Plasma membrane
B) Biological membrane
C) Trans membrane
D) Peripheral membrane
E) Integral membrane

Question 12

The term "fluid mosaic model" refers to

A) the solubility of water in the membrane.
B) the method of substance transport across the membrane.
C) the movement of surface proteins through the membrane.
D) the diffusion of lipid-soluble substances across the lipid bilayer.
E) the movement of lipids and integral proteins within the lipid bilayer.

Question 13

Which of the following statements about phospholipids is false ?

A) They are amphipathic molecules.
B) They contain three fatty acids chains.
C) They contain a polar organic group attached to a phosphate group.
D) They have cylindrical shapes that allow them to associate with water most easily as a bilayer structure.
E) They have two distinct regions, one strongly hydrophobic and the other strongly hydrophilic.

Question 14

Which molecule is least likely to cross a cellular membrane by simple diffusion?

A) Water
B) Oxygen
C) Nitrogen
D) Potassium ion
E) Carbon dioxide

Question 15

Which cellular mechanism ejects products, such as hormones, by the fusion of a vesicle with the plasma membrane?

A) Endocytosis
B) Phagocytosis
C) Pinocytosis
D) Exocytosis
E) Receptor-mediated endocytosis

Question 16

Which statement about plasma membranes is false ?

A) Plasma membranes regulate the passage of materials.
B) Plasma membranes divide the cell into compartments.
C) Plasma membranes serve as surfaces for chemical reactions.
D) Plasma membranes prevent communication with other cells.
E) Plasma membranes transmit signals between the environment and the interior of the cell.

Question 17

What does an ABC transporter use to move larger ions and molecules across the cell membrane?

A) ATP
B) Water
C) Porins
D) Signals
E) Tunnels

Question 18

A transmembrane protein differs from other membrane proteins because

A) it completely extends through the membrane.
B) it is a glycoprotein with carbohydrates attached.
C) it is completely embedded within the membrane.
D) it is attached to the inside of the membrane by an ionic bond.
E) it is covalently linked to the outer surface of the plasma membrane.

Question 19

How are integral proteins unique in cell membranes?

A) They have no hydrophobic portions.
B) They are weakly bound to the surface of the membrane.
C) They are only located on the inner side of a membrane.
D) They are firmly bound to the membrane.
E) They are completely embedded within the lipid bilayer.

Question 20

Which proteins are located on the inner or outer surface of the plasma membrane, usually bound to exposed regions of integral proteins by noncovalent interactions?

A) Plasma membrane proteins
B) Biological membrane proteins
C) Transmembrane proteins
D) Peripheral membrane proteins
E) Integral membrane proteins

Question 21

What process halts the net movement of water from a hypotonic solution into a plant's cells and often provides the structural support to many plants?

A) Plasmolysis
B) Turgor pressure
C) Osmotic pressure
D) Facilitated diffusion
E) Dynamic equilibrium

Question 22

Since sodium-potassium pumps transport sodium ions out of a cell and potassium ions into a cell, what type of carrier proteins are they?

A) Ion pumps
B) Uniporters
C) Symporters
D) Antiporters
E) ABC transporter

Question 23

Fluid that has a higher osmotic pressure than a cell is called ___________.

A) hypotonic
B) hypertonic
C) turgor pressure
D) isotonic
E) plasmolysis

Question 24

You light a scented candle in the guest bathroom. Within a few minutes, you can smell the candle's scent throughout the hallway. What process is occurring?

A) Dialysis
B) Osmosis
C) Simple diffusion
D) Active transport
E) Facilitated diffusion

Question 25

A patient who has had a severe hemorrhage accidentally receives a large transfusion of distilled water directly into a major blood vessel. What effect will this have on the patient?

A) It will have no unfavorable effect as long as the water is free from bacteria.
B) It will have serious, perhaps fatal consequences because there would be too much fluid to pump.
C) It will have serious, perhaps fatal consequences because the red blood cells could shrink.
D) It will have serious, perhaps fatal consequences because the red blood cells could swell and burst.
E) It will have no serious effect because the kidney could quickly eliminate excess water.

Question 26

What is the passive movement of water along a concentration gradient?

A) Osmosis
B) Cotransport
C) Plasmolysis
D) Simple diffusion
E) Facilitated diffusion

Question 27

If the concentration of solutes in a cell is less than the concentration of solutes in the surrounding fluid, then the extracellular fluid is said to be

A) stable.
B) isotonic.
C) hypotonic.
D) hypertonic.
E) amphipathic.

Question 28

Fluid that has a higher osmotic pressure than a cell is called ___________.

A) hypotonic
B) hypertonic
C) turgor pressure
D) isotonic
E) plasmolysis

Question 29

Once ligand molecules bind to receptors in coated pits of a plasma membrane, the next step of receptor-mediated endocytosis would be

A) coating detaches from vesicle.
B) coated vesicle forms by endocytosis.
C) ligands separate from receptors, which are recycled.
D) contents of secondary lysosome are digested and released into the cytosol.
E) endosome fuses with primary lysosome, forming secondary lysosome.

Question 30

What have studies of glucose transport in liposomes revealed?

A) Glucose is transported against a concentration gradient.
B) Glucose moves readily across the membrane by simple diffusion.
C) Glucose phosphates move readily across the membrane by simple diffusion.
D) The binding of glucose triggers a conformational change in the carrier protein.
E) The transport of solutes via carrier proteins is faster than via channel proteins.

Question 31

Figure 5-1 ​

Refer to the accompanying figure. Which best describes what is happening to the red blood cells in Fig. A?

A) Pinocytosis has occurred.
B) Plasmolysis has occurred.
C) There has been no net water movement.
D) There has been a net flow of water out of the cell.
E) There has been a net flow of water into the cell.

Question 32

Figure 5-1 ​

Refer to the accompanying figure. Which best describes the red blood cells in Fig. B?

A) These red blood cells have been placed in an isotonic solution.
B) These red blood cells have swollen in response to a hypertonic external solution.
C) These red blood cells have swollen in response to a hypotonic external solution.
D) These red blood cells have shrunk in response to a hypertonic external solution.
E) These red blood cells have shrunk in response to a hypotonic external solution.

Question 33

In cells that are constantly involved in secretion, an equivalent amount of membrane must be returned to the interior of the cell for each vesicle that fuses with the plasma membrane; if this does not occur, then what would happen?

A) The cell surface would shrivel.
B) The cell surface will keep expanding.
C) The surface area would remain constant.
D) The number of membrane receptor proteins would decrease.
E) The ratio of cell surface would decrease, compared to cell volume.

Question 34

When the net movement of water in and out a cell is zero, that solution is said to be

A) osmotic.
B) isotonic.
C) hypotonic.
D) hypertonic.
E) pressurized.

Question 35

The process by which the plasma membrane separates from the cell wall is called ______.

A) hypotonic
B) hypertonic
C) turgor pressure
D) isotonic
E) plasmolysis

Question 36

The role of ATP in the sodium-potassium pump is

A) to transfer Na⁺ to the inside of a cell.
B) to assist a Na⁺ to bind to a carbohydrate.
C) to transfer Na⁺ to the outside of a cell.
D) to assist a cell to release Na⁺ by exocytosis.
E) to assist a cell to take up Na⁺ by endocytosis.

Question 37

What happens during the cotransport of glucose and sodium ions?

A) The transport of glucose powers the transport of sodium.
B) ATP causes a conformational change in the carrier protein.
C) Both D and E
D) Glucose molecules are transported against their concentration gradient.
E) Sodium ions are transported down their concentration gradient.

Question 38

What is required for facilitated diffusion to take place?

A) Energy from ATP
B) A transmembrane protein
C) The transport of large food particles
D) The transport of small nonpolar molecules
E) Movement down a concentration gradient

Question 39

The sodium-potassium pump is a carrier protein that maintains a(n) ____ gradient across the plasma membrane.

A) polar
B) nonpolar
C) phosphorous
D) concentration
E) electrochemical

Question 40

Although glucose molecules constantly diffuse into a red blood cell along their concentration gradient, equilibrium is never reached and a steep concentration gradient is continually maintained. What causes this?

A) The active transport of glucose
B) The very fast turnover rate of glucose metabolism
C) The ability of the cell to engulf glucose by pinocytosis
D) The continuous excretion of glucose from other parts of the cell
E) The rapid addition of a phosphate to the glucose molecules

Question 41

Plasmodesmata of plant cells are functionally equivalent to the ____ of animal cells.

A) vesicles
B) gap junctions
C) tight junctions
D) anchoring junctions
E) cell surface receptors

Question 42

How do gap junctions differ from desmosomes?

A) A gap junction bridges the space between cells.
B) A gap junction is a much larger space between cells.
C) A gap junction provides communication between cells.
D) A gap junction can control the passage of materials between cells.
E) A gap junction requires the use of ATP to open and close its channels.

Question 43

A person has a genetic disease that prevents the phospholipids in the plasma membrane of the white blood cells from freely fusing with the other membranes within the cell. How would this disease affect phagocytosis?

A) Endocytosis would not occur.
B) Lysosomes would not be formed.
C) Facilitated diffusion would not occur.
D) Lysosomes would be formed lacking hydrolytic enzymes.
E) The phagocytic vacuole would not fuse with the lysosome.

Question 44

Briefly describe what would happen to red blood cells placed in a solution of 0.5% sodium chloride.

Question 45

Identify and discuss three different roles for membrane proteins.

Question 46

Mutations to ABC transporter genes contribute to cystic fibrosis.

Question 47

Figure 5-2  

What cellular process is represented in the accompanying figure?

A) Lysis
B) Exocytosis
C) Cotransport
D) Pinocytosis
E) Facilitated diffusion

Question 48

Figure 5-3 ​

In the accompanying figure, what is the form of cellular junction?

A) Desmosomes
B) Gap junctions
C) Tight junctions
D) Plasmodesmata
E) Adhering junctions

Question 49

Figure 5-2  

Consider the cellular process illustrated in the accompanying figure. What substance would most likely be transported in this manner?

A) Glucose
B) Bacteria
C) Hormones
D) Potassium ions
E) Carbon dioxide

Question 50

The peripheral membrane proteins can be easily removed without disrupting the bilayer structure of the membrane.

Question 51

Sketch and label a typical cell membrane. Provide a brief explanation for each of the labeled structures.

Question 52

What type of cellular junction cements cells together that use cadherins as a belt around each cell?

A) Desmosomes
B) Gap junctions
C) Tight junctions
D) Plasmodesmata
E) Adhering junctions

Question 53

Sketch and label a tight junction, desmosome, and gap junction.

Question 54

Figure 5-3 ​

In the accompanying figure, what is the role of the structures between the membranes?

A) They provide structure to plant cells.
B) They provide anchorage points between adjacent cells.
C) They allow passage of materials through intercellular spaces.
D) They prevent the passage of materials through intercellular spaces.
E) They allow the transport of small molecules and ions between adjacent cells.

Question 55

Compare simple diffusion, osmosis, and facilitated diffusion. Identify examples for each.

Question 56

What method does a human white blood cell employ to engulf a bacterial cell?

A) Osmosis
B) Exocytosis
C) Pinocytosis
D) Phagocytosis
E) Facilitated diffusion

Question 57

Biological membranes are one-dimensional fluids.

Question 58

In cell membranes, cholesterol and glycoproteins are exposed to the extracellular surface for cell recognition and adhesion to other cells.

Question 59

Carrier proteins are also called ______.

A) passive transport
B) active transport
C) aquaporins
D) pores
E) transporters

Question 60

Groups of eight connexin molecules cluster to form a cylinder that spans the plasma membrane.

Question 61

In the sodium-potassium pump, sodium ion release causes the carrier protein to return to its original shape and releases two K⁺ ions into the cell.
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Question 62

LDL cholesterol is taken into the cell by receptor-mediated endocytosis.

Question 64

Most plasmodesmata contain a narrow cylindrical structure, called the desmotubule, which runs through the channel and connects the smooth ER of the two adjacent cells.

Question 66

Compare and contrast the mechanisms of the hydrogen pump and glucose-sodium cotransport systems.

Question 70

Compare and contrast the processes of facilitated diffusion and active transport.

Question 71

Cotransport systems directly provide energy for active transport of solutes.

Question 72

Describe some of the activities performed by membrane proteins in multicellular organisms.

Question 73

Plasmolysis occurs in plant cells when the soil or water contains low concentrations of salts or fertilizers.