Deck 5: A Closer Look at Cell Membranes

Question 1

A membrane is more "fluid" than solid because

A)phospholipid tails prevent close packing.
B)proteins can shift positions.
C)water is the main component.
D)phospholipid tails prevent close packing, and proteins can shift positions.
E)phospholipid tails prevent close packing, proteins can shift positions, and water is the main component.

Answer 1

D

Question 2

Most of the functions of plasma membranes are carried out by

A)cholesterol.
B)proteins.
C)hydrophilic heads.
D)hydrophobic tails.
E)carbohydrates.

Answer 2

B

Question 3

Cystic fibrosis

A)results from a mutation in a specific membrane transport protein.
B)is characterized by inadequate chloride and water movement across epithelial cells.
C)causes low grade bacterial infections in the lungs to persist for years.
D)is a common, fatal genetic disorder.
E)is all of these.

Answer 3

E

Question 4

A water-soluble hormone would most likely bind to which of the following membrane proteins?

A)adhesion
B)recognition
C)receptor
D)communication
E)transport

Question 5

A mutated form of the CFTR gene is associated with

A)recognition proteins.
B)gap junction formation.
C)peripheral proteins in plasma membranes.
D)sinus problems.
E)passive transporters.

Question 6

The relative impermeability of membranes to water-soluble molecules is a result of the

A)nonpolar nature of water molecules.
B)presence of large integral membrane proteins.
C)presence of inorganic salt crystals scattered through some membranes.
D)presence of cutin and lignin in the membranes.
E)presence of phospholipids in the lipid bilayer.

Question 7

If a plasma membrane were compared to a sandwich, __________ would be considered the filling.

A)cholesterol
B)protein
C)hydrophilic heads
D)hydrophobic tails
E)carbohydrates

Question 8

In an attempt to visualize the fluid mosaic model of a membrane, we could describe the __________ as floating in a sea of __________.

A)lipid; protein.
B)phospholipids; carbohydrate.
C)proteins; lipid.
D)fats; water.
E)glycolipids; sterols.

Question 9

Which statement is true of plasma membranes?

A)They have molecules on their surfaces that identify them.
B)They are essentially impermeable.
C)They are basically static, non-changing structures.
D)They are hydrophilic barriers between cells.
E)They function primarily through the activity of their carbohydrates.

Question 10

Which of the following statements is true?

A)When lipids and water are mixed, it is the water molecules that isolate themselves into droplets.
B)When lipids and water are mixed, the lipids dissolve and enter into a solution.
C)Lipids are nonpolar and will not dissolve in water.
D)Polar substances are able to pass through a plasma membrane more readily than nonpolar substances.
E)All portions of a phospholipid molecule found in a membrane are classified as nonpolar.

Question 11

Which of the following statements is NOT true?

A)A lipid bilayer is characteristic of all membranes.
B)Cellular organelles are associated with membranes.
C)In a plasma membrane, a hydrophilic portion is oriented to the outside of the cell.
D)Lipid molecules make the cell membrane relatively impermeable to water-soluble substances.
E)Even by using extremely high magnification, an electron microscope cannot reveal the substructure of cell membranes.

Question 12

Which of the following statements is false?

A)The plasma membrane is more like a fluid than a solid.
B)The cell membrane is symmetrical, so it is impossible to identify which is the extracellular surface.
C)Calcium pumps move calcium ions across the membrane.
D)In a plasma membrane, proteins shift positions and phospholipids flex their tails.
E)There are functional differences between the two sides of the plasma membranes.

Question 13

Which statement is NOT true?

A)Membranes are often perforated by proteins that extend through both sides of the membrane.
B)Some membranes have proteins with channels that allow for the passage of hydrophilic substances.
C)Hydrophilic substances have an easier time passing through membranes than do hydrophobic substances.
D)The current concept of a membrane is best summarized by the fluid mosaic model.
E)All of these.

Question 14

Unsaturated tails of lipids

A)are hydrophilic.
B)are unstable and tend to break apart.
C)interact with the tails of other phsopholipids .
D)will break whenever exposed to phosphate ions.
E)have all of these attributes.

Question 15

A transport protein is most analogous to a

A)water pipe.
B)subway train.
C)light switch.
D)voice identification device.
E)television receiver.

Question 16

Which of the following is true regarding cell membrane proteins?

A)All are free to move laterally through the lipid bilayer.
B)All are rigidly positioned.
C)Some are tethered by cytoskeletal elements.
D)Some form complexes.
E)Some are tethered by cytoskeletal elements, and some form complexes.

Question 17

Hydrophobic reactions of phospholipids can produce clusters of their fatty-acid tails to form

A)a lipid bilayer.
B)hydrolysis of the fatty acids.
C)a protein membrane.
D)a cytoskeleton.
E)a nonpolar membrane.

Question 18

Cholesterol

A)is not found in plant membranes.
B)is the main steroid component of animal cell membranes.
C)is the main animal equivalent of plant phytosterols.
D)has a simple OH group in its hydrophilic part.
E)has all of these attributes.

Question 19

Unsaturated tails tend to __________ at the sites of their double bonds.

A)dissolve
B)kink or bend
C)separate
D)react with ions
E)do none of these

Question 20

A hypothetical "microbullet" shot through a phospholipid bilayer would pass the components in which order?

A)tail >>> tail >>> head >>> head
B)head >>> tail >>> head >>> tail
C)tail >>> head >>> head >>> tail
D)head >>> tail >>> tail >>> head
E)head >>> head >>> tail >>> tail

Question 21

Distilled water refers to water that is nearly free of

A)solutes.
B)ions.
C)gases.
D)suspended solids.
E)none of these.

Question 22

The carrier molecules used in active transport are

A)calcium ions in the calcium pump.
B)proteins.
C)ATP molecules.
D)carbohydrates.
E)lipids.

Question 23

The method of movement that requires the expenditure of ATP molecules is

A)simple diffusion.
B)facilitated diffusion.
C)osmosis.
D)active transport.
E)bulk flow.

Question 24

Which substance passes most readily into a cell?

A)ions
B)large molecules
C)glucose
D)carbon dioxide
E)polar molecules

Question 25

Active transport

A)works against concentration gradients.
B)works with concentration gradients.
C)requires ATP-driven protein motors.
D)requires channel proteins to change shape.
E)does none of these.

Question 26

Which is false regarding passive transport?

A)It depends on concentration or electrical gradients.
B)It involves weak binding between solute and protein.
C)It requires an energy input.
D)It depends on protein shape change.
E)None of these are false.

Question 27

Which of the following proteins is not necessarily associated with the plasma membrane?

A)recognition protein
B)plasma protein
C)receptor protein
D)channel transport protein
E)adhesion protein

Question 28

The rate of diffusion through a selectively permeable membrane will be lowest when which of the following is(are) true? I.Concentration gradients are steep.
II)Temperatures are low.
III)Solutes are small molecules.

A)I only
B)II only
C)I and III
D)II and III
E)I, II, and III

Question 29

This illustration shows the mechanism of

A)simple diffusion.
B)bulk flow.
C)endocytosis.
D)facilitated diffusion.
E)an active transporter.

Question 30

In simple diffusion,

A)the rate of movement of molecules is influenced by temperature and pressure.
B)the movement of individual molecules is random.
C)the movement of molecules of one substance is independent of the movement of any other substance.
D)the net movement is away from the region of highest concentration.
E)all of these happen.

Question 31

Movement of a molecule against a concentration gradient is

A)simple diffusion.
B)facilitated diffusion.
C)osmosis.
D)active transport.
E)bulk flow.

Question 32

Oxygen, carbon dioxide, and other small nonpolar molecules cross the plasma membrane through the process(es) of

A)osmosis.
B)diffusion.
C)endocytosis and exocytosis.
D)active transport.
E)facilitated diffusion.

Question 33

The net direction that an ion or molecule moves is

A)dependent upon the size of the molecule.
B)unpredictable because movement is random.
C)influenced by the temperature of the medium.
D)influenced by the membranes in the vicinity.
E)the result of concentration differences.

Question 34

The sodium-potassium pump is an example of

A)simple diffusion.
B)facilitated diffusion.
C)osmosis.
D)active transport.
E)bulk flow.

Question 35

A concentration gradient ceases to exist when

A)all the molecules have moved from high concentration to low.
B)the membrane pores close.
C)the temperature drops.
D)there is no net movement.
E)bulk flow intervenes.

Question 36

Movement of matter or energy in nature may be the result of

A)concentration gradients.
B)differential pressures.
C)differences in electrical charges.
D)the existence of thermal differentials.
E)all of these.

Question 37

Which of the following affects the rate of diffusion through a selectively permeable membrane? I.concentration gradient
II)temperature
III)molecular size

A)I only
B)II only
C)I and II
D)II and III
E)I, II, and III

Question 38

The glucose transport mechanism is an example of

A)simple diffusion.
B)facilitated diffusion.
C)osmosis.
D)active transport.
E)bulk flow.

Question 39

Which of these three mechanisms illustrates facilitated diffusion?

A)A
B)B
C)C
D)both A and B
E)none of these

Question 40

Which of the following does NOT require the participation of a membrane protein?

A)active transport
B)exocytosis
C)facilitated diffusion
D)simple diffusion
E)all of these require a protein

Question 41

A red blood cell will burst when placed in which of the following kinds of solution?

A)hypotonic
B)hypertonic
C)isotonic
D)any of these
E)none of these

Question 42

If a plant cell is placed in a hypotonic solution, the

A)entire cell will not swell or shrink.
B)entire cell will shrink.
C)turgor pressure will increase.
D)cell wall prevents the cell from exploding.
E)turgor pressure will increase, but the cell wall prevents the cell from exploding.

Question 43

During receptor-mediated endocytosis

A)plasma membrane receptors bind molecules to be enclosed.
B)a small pit forms beneath the receptors.
C)a pit closes back on itself.
D)a vesicle forms.
E)all of these occur.

Question 44

Exocytotic vesicles develop from the membranes of which of the following structures?

A)mitochondria
B)Golgi bodies
C)lysosomes
D)vacuoles
E)phagocytes

Question 45

Wilting of a plant occurs

A)if the plant is placed in an isotonic solution.
B)if there is a rise in turgor pressure.
C)as a result of facilitated diffusion.
D)when a plant with flexible cell walls is placed in a hypertonic solution.
E)as a result of all of these conditions.

Question 46

White blood cells use __________ to get rid of foreign particles in the blood.

A)simple diffusion
B)bulk flow
C)osmosis
D)phagocytosis
E)facilitated diffusion

Question 47

The action of a white blood cell engulfing a bacterium is

A)pinocytosis.
B)phagocytosis.
C)exocytosis.
D)endocytosis.
E)phagocytosis and endocytosis.

Question 48

Which of the following is NOT a form of passive transport?

A)osmosis
B)facilitated diffusion
C)simple diffusion
D)exocytosis
E)none of these

Question 49

Phagocytosis involves all EXCEPT which of these?

A)receptors
B)a meshwork of microfilaments
C)pseudopod formation
D)bulk-phase endocytosis
E)vesicle fusion with lysosomes

Question 50

The above figure represents which of the following?

A)simple diffusion
B)bulk flow
C)osmosis
D)phagocytosis
E)endocytosis