Deck 4: Cell Membranes, Transport, and Communication

Question 1

All movement,including that of diffusing molecules,requires a small expenditure of energy;which of the following small sources of energy is most likely to make diffusion possible across the cell membrane from the cell exterior into the cell interior?

A) Cells hydrolyze ATP to provide the energy for diffusion.
B) A small percentage of the diffusing molecules react chemically with the membrane.
C) Thermal energy is present in the extracellular environment.
D) Gravity forces the molecules to move downhill.

Answer 1

C

Question 2

Imagine two solutions separated by a selectively permeable membrane that is impermeable to glucose.On one side of the membrane,solution A contains 10 percent glucose and on the other side,solution B contains 25 percent glucose.Which of the following is true?

A) Solution A is hypertonic relative to solution B.
B) The concentration of water is greatest in solution B.
C) Water will move from solution A to solution B.
D) Glucose will diffuse from solution B to solution A.

Answer 2

C

Question 3

You observe a cell in a solution that swells until it bursts.What you have seen is an instance of osmosis in a(n)________ solution.

A) hypertonic
B) isotonic
C) hypotonic
D) exotonic

Answer 3

C

Question 4

The concentration of glucose inside a cell is higher than the concentration outside that cell,yet glucose continues to enter the cell.This is an example of

A) passive transport.
B) diffusion.
C) active transport.
D) osmotic transport.

Question 5

Which of the following types of molecules could NOT easily diffuse across a plasma membrane?

A) sugar
B) water
C) oxygen
D) carbon dioxide

Question 6

The following figure shows the movement of solutes across a plasma membrane in the direction indicated by the arrows.

This movement across the membrane

A) requires a direct input of cellular energy.
B) occurs independently of carrier proteins.
C) occurs by diffusion.
D) is an example of osmosis.

Question 7

Active transport requires

A) cellular energy,usually in the form of ATP.
B) thermal energy from the environment.
C) hormonal activation of specific protein carriers.
D) the initial movement of water by osmosis to develop a favorable concentration gradient.

Question 8

You place some Elodea,an aquarium plant,in a hypertonic solution.The cells of the Elodea

A) begin to hemolyze.
B) start to burst.
C) shrink.
D) undergo plasmolysis.

Question 9

Which type of molecule will diffuse through the plasma membrane most quickly?

A) a small polar molecule like water
B) a small nonpolar molecule like carbon dioxide
C) a large polar molecule like glucose
D) a large nonpolar molecule like testosterone

Question 10

Which of the following would directly supply energy to an active carrier protein?

A) starch
B) sugars
C) ATP
D) fatty acids

Question 11

Hikers can detect a dead skunk along a trail long before they actually see it.What process allows the scent of the skunk to be so widely dispersed?

A) osmosis
B) active transport
C) diffusion
D) transduction

Question 12

Active transport

A) moves substances out of cells,but not into them.
B) occurs in dense patches far removed from passive carrier proteins.
C) moves substances from areas of high concentration to areas of low concentration.
D) involves a carrier protein.

Question 13

Passive carrier proteins

A) bind to phospholipids in the plasma membrane and move them into the cell.
B) bind to specific external molecules and aid in the formation of vesicles entering the cell.
C) create tunnels in the plasma membrane through which specific solutes can diffuse.
D) change shape upon binding to specific external molecules and then release the molecule on the other side of the membrane.

Question 14

A cell that is gaining water from its surroundings is in a(n)________ solution.

A) hypertonic
B) hypotonic
C) isotonic
D) endotonic

Question 15

Which statement best describes the equilibrium condition shown in the following illustration?

A) A sample taken from anywhere in the container will have the same concentration of solute.
B) Eventually,gravity will move most solute particles to the bottom of the container.
C) The molecular motion that initially distributed the solute ceased once the equilibrium was established.
D) If the temperature of the pitcher had been lowered,equilibrium would have been attained more quickly.

Question 16

One of the major functions of the plasma membrane is to

A) prevent the loss of proteins from mitochondria.
B) contract and give animals their ability to move.
C) control what enters and leaves a cell.
D) provide physical support to the nucleus.

Question 17

As a biological process,osmosis

A) requires an input of cellular energy.
B) moves solute from areas of high concentration to areas of low concentration.
C) is a type of passive transport.
D) requires reorganization of the plasma membrane.

Question 18

The fragrance of bread baking in a kitchen spreads to other rooms by

A) active transport.
B) diffusion.
C) osmosis.
D) selective permeation.

Question 19

The following figure illustrates a plasma membrane.

Which substance in the figure is crossing the membrane using simple diffusion?

A) Ca²⁺
B) Na⁺
C) K⁺
D) H₂O

Question 20

The arrows in the following figure show the movement of water across the cell wall and plasma membrane of a plant cell.

For water to move in the direction indicated,the solution surrounding the cell must be

A) hypertonic.
B) hypotonic.
C) isotonic.
D) selectively impermeable.

Question 21

A white blood cell at the site of a puncture wound engulfs a large cluster of bacteria forming a large internal vesicle.This is an example of

A) exocytosis.
B) pinocytosis.
C) receptor-mediated endocytosis.
D) phagocytosis.

Question 22

Multicellular organisms have various specialized cells because

A) any one cell can contain only one kind of organelle.
B) each kind of cell is able to function in isolation.
C) specialized cells ensure that processes necessary for life occur efficiently.
D) the DNA of cells is not accurately copied.

Question 23

You observe a vesicle moving toward the plasma membrane from inside a cell.Once it reaches and fuses with the plasma membrane,you will most likely see an example of

A) receptor-mediated endocytosis.
B) pinocytosis.
C) phagocytosis.
D) exocytosis.

Question 24

To coordinate the functions of specialized cells,those cells must be able to

A) communicate.
B) replicate.
C) move from place to place.
D) cut up certain proteins.

Question 25

In the following flowchart summarizing membrane transport,both active and facilitated transports terminate at separate carrier proteins.Which statement explains why the lines do not converge at the same carrier protein?

A) The two processes move items across the membrane in opposite directions;the carriers are positioned on opposite sides of the membrane.
B) During facilitated transport,hydrophobic molecules cross the membrane;hydrophilic molecules require active transport to cross the membrane.
C) Energy is required to drive an active transport carrier protein,whereas a facilitated carrier operates down the concentration gradient and requires no energy input.
D) Active transporters move only ions with net charge,whereas facilitated transporters move only polar or neutral molecules.

Question 26

Imagine a cell needing an essential specific amino acid (one the cell cannot synthesize).What process could acquire the amino acid most quickly?

A) Phagocytize and digest bacteria,extract the specific amino acid from the residue,and release to the cytoplasm.
B) Place a transporter protein in the membrane that could carry the amino acid across the membrane.
C) Use receptor-mediated endocytosis.
D) Use simple diffusion because the concentration of the needed amino acid will be zero and the gradient will always be maximized.

Question 27

Sex hormones are able to interact with their receptors in the cytoplasm or in a membrane-bound organelle like the nucleus because they are

A) isotonic.
B) hydrophobic.
C) hydrophilic.
D) very large.

Question 28

Animal cells are attached to neighboring cells by all of the following,EXCEPT

A) anchoring junctions.
B) gap junctions.
C) tight junctions.
D) plasmodesmata.

Question 29

To coordinate the contraction of the numerous muscle cells that form the heart,signals must travel rapidly between muscle cells.To allow this rapid communication,muscle cells in the heart are connected by

A) tight junctions.
B) gap junctions.
C) anchoring junctions.
D) carrier proteins.

Question 30

Which of the following is found in plants?

A) plasmodesmata
B) tight junctions
C) gap junctions
D) anchoring junctions

Question 31

Objects suspended in the extracellular fluid can cross the plasma membrane and enter a cell by all of the following processes,EXCEPT

A) pinocytosis.
B) receptor-mediated endocytosis.
C) phagocytosis.
D) osmosis.

Question 32

If a red blood cell is placed in a hypertonic solution,what happens to it?

A) It will burst.
B) It will shrink.
C) There will be no change in the red blood cell.
D) Water will move into the red blood cell faster than it will move out.

Question 33

What best explains the double-headed arrows associated with carbon dioxide and molecular oxygen shown in the following illustration?

A) Individual molecules are unable to cross the membrane,but they can be found in relatively large numbers on both sides.
B) The membrane is permeable to these small molecules and they enter or leave rapidly as their concentration gradients change.
C) An isotonic condition exists for each molecule,so no net movement takes place.
D) Homeostasis requires that surplus molecules entering the cell be rejected and returned to the outside.

Question 34

You place some Elodea,an aquarium plant,in a hypotonic solution.What happens?

A) Water predominantly moves out of the Elodea cells,and they shrink.
B) Water predominantly moves into the Elodea cells,and they burst.
C) Water predominantly moves into the Elodea cells;turgor pressure rises,but the cells do not burst.
D) Water moves into and out of the Elodea cells at the same rate.

Question 35

When placed in a 2 percent sucrose solution,red blood cells shrink (lose volume);relative to the red blood cell cytoplasm,a 2 percent solution must be

A) less concentrated (hypotonic).
B) more concentrated (hypertonic).
C) equally concentrated (isotonic).
D) equally concentrated (equitonic).

Question 36

Ingested protein is always degraded to amino acids before absorption in the mature human small intestine,but nursing infants can absorb intact antibodies (large protein molecules)from breast milk.How might this difference in intestinal function be explained?

A) The tight junctions that prevent molecules from creeping through the epithelial lining of the small intestine are not yet fully developed in infants.
B) The anchoring junctions that interlock adjacent cells can be selectively activated or disabled in infants to permit the selective passage of specific substances.
C) Infants have gap junctions that open to the lumen of the small intestine and admit appropriately sized proteins.
D) The plasmodesmata do not fully develop until after an infant has been weaned,allowing the antibodies to be absorbed until then.

Question 37

Epithelial tissue in animals provides a barrier against the invasion of bacteria into the body.Which of the following is most likely to be responsible for creating a tight enough barrier between cells to prevent the passage of bacteria between them?

A) anchoring junctions
B) gap junctions
C) tight junctions
D) plasmodesmata

Question 38

Cell surface receptors of chemical messages are made of

A) protein.
B) DNA.
C) lipids.
D) sugars.

Question 39

Signaling molecules can affect a cell from the outside by interacting with specific receptors that are located

A) in the plasma membrane.
B) within the cell's organelles.
C) within chloroplasts.
D) on the cell wall.

Question 40

A red blood cell is placed in a solution and it begins to shrink.Which of the following describes the solution?

A) hypertonic
B) isotonic
C) hypotonic
D) supertonic

Question 41

A concentration ________ is said to exist when a molecule is more abundant in one area than it is in another.

Question 42

Elevated HDL (high-density lipoprotein)levels seem to provide positive cardiovascular health effects,even for individuals with abnormally high blood cholesterol.What best describes the beneficial action of HDL?

A) HDL lines the blood vessel walls,preventing the attachment of cholesterol and the consequential inflammation that follows.
B) HDL is an anti-inflammatory agent;it suppresses the inflammatory response in blood vessel walls following the entry of cholesterol.
C) HDL has cardiostimulatory effects;it elevates heart rate and blood pressure in a fashion similar to exercise.
D) HDL collects surplus cholesterol from peripheral tissues and transports it to the liver,reproductive,and adrenal glands where it is converted to bile or hormones.

Question 43

Which of the following statements about hormones is FALSE?

A) They are not used in the part of the body where they are produced.
B) They are long-range signaling molecules.
C) They are not used by multicellular organisms.
D) They are transported in an organism by fluids.

Question 44

The human hormone insulin is produced only by a single organ,the pancreas,yet insulin is used to move glucose from the bloodstream into cells all over the body.What aspect of hormones makes it possible for insulin to work throughout the body?

A) Hormones are able to stop cell-to-cell communication.
B) Hormones all cross cell membranes,and thus can move freely throughout the body.
C) Hormones cause rapid cell-to-cell signaling.
D) Hormones are long-range signaling molecules.

Question 45

The passive movement of water across a selectively permeable membrane is called ________.

Question 46

Hydrophilic signaling molecules

A) move into cells by active transport through carrier protein channels.
B) bind to cell surface receptors and do not enter cells.
C) can passively cross the plasma membrane and bind to intracellular receptor proteins.
D) move directly into the nucleus through carrier proteins that span the distance from the plasma membrane to the nuclear envelope.

Question 47

Muscle cells require high concentrations of calcium to function properly.As a result,these cells use ________ transport to move calcium from areas of low concentration outside the cell into the cytoplasm.

Question 48

Water moves across a membrane from a hypotonic solution to a ________ solution.

Question 49

After a sex hormone enters a target cell,it

A) binds to the nucleus.
B) becomes a signaling protein.
C) binds to an internal receptor protein.
D) becomes a gene.

Question 50

Lipids often move within the body in complexes known as lipoproteins;what advantage does this strategy provide?

A) Lipids alone have high solubility in body fluids and would be difficult to transport.
B) With a protein component as an identifier,cells needing lipids can use membrane receptors and acquire only as much lipid as they need at any given moment.
C) Rather than simply diffusing into adjacent cell membranes as free lipids would do,surplus lipoproteins can be routed to the kidneys for disposal or modification.
D) Lipids associated with lipoproteins are more likely to be able to pass freely through the cell membrane.

Question 51

For a cell to be a target for a particular hormone,it must usually

A) have an ATP source.
B) have a receptor for that particular hormone.
C) be larger than normal.
D) have a receptor for any hormone.

Question 52

Cell signaling

A) is always a rapid process.
B) can be fast or slow.
C) is always a slow process.
D) does not occur in plants.

Question 53

The concentration of solutes is higher within the mitochondria than it is in the cytosol.Therefore,the cytosol is ________ to the inside of the mitochondrion.

Question 54

Many hormones are large and hydrophilic.Where would you expect the receptor proteins for these hormones to be located?

A) in the cell membrane with the hormone-binding site exposed to the cell interior
B) in the hydrophilic portion of the cell membrane
C) in the cytoplasm of a cell
D) in the cell membrane with the hormone-binding site exposed to the cell exterior

Question 55

Soon after a certain molecule enters a cell,the cell begins producing a new type of protein.The molecule was probably a

A) receptor molecule.
B) hydrophilic molecule.
C) carrier protein.
D) hydrophobic hormone.

Question 56

Short-lived signaling molecules are most effective for

A) long-distance cell-to-cell communication.
B) local cell-to-cell communication.
C) activating genes in the nucleus.
D) breaking down receptor proteins.

Question 57

Which of the following signaling molecules would NOT be found in animals?

A) auxin
B) insulin
C) adrenaline
D) testosterone

Question 58

Some hormones,like thyroxine,affect most or all body cells,while others only affect a single organ or type of cell.This is because of variations in

A) hormone concentration-when present in high concentration,a hormone can stimulate a greater number of body locations.
B) receptor distribution-all cells or organs with receptors for the hormone will be affected.
C) membrane permeability-hydrophobic hormones enter and affect all cells,whereas hydrophilic hormones have more limited affects.
D) signal transduction-only cells with the appropriate enzymes needed to activate the hormone will respond to its signal.

Question 59

Elevated cholesterol and LDL (the particles that transport cholesterol)have been strongly associated with vascular disease;what process(es)lead to the elevated levels?

A) excessive absorption of cholesterol from the GI tract
B) reduced production of cholesterol by the liver
C) increased acceptance of cholesterol by body cells
D) reduced conversion of cholesterol into sex hormone receptor molecules

Question 60

Signaling molecules can be "tagged" by attaching glow-in-the-dark molecules to them.After adding tagged signaling molecules to the fluid around several cells,you observe the cells with a microscope designed to see the glow-in-the-dark molecules.After a few minutes,you notice that the plasma membrane of some of the cells begins to glow.This observation indicates that some cells

A) have more dense plasma membranes than others.
B) have receptors for the signaling molecule.
C) have no active carrier proteins for the signaling molecules.
D) block the signaling molecules by repelling them.

Question 61

During ________ endocytosis,specific substances interact with proteins located in the plasma membrane of the cell.

Question 62

Cells suspended in a hypertonic solution will lose water.

Question 63

After entering its target cell,a hydrophobic hormone binds to its intracellular receptor and then interacts with the cell's DNA,resulting in the production of a specific ________.

Question 64

Cells in the liver typically acquire cholesterol by receptor-mediated ________.

Question 65

The principle of cell ________ is that different cells in the same organism may have different functions.

Question 66

Osmoregulation refers to balancing water concentrations in organisms and cells.

Question 67

The various connections between cells,including cell junctions and signaling molecules,allow the cells in a multicellular organism to "talk" to each other,a principle known as cell-to-cell ________.

Question 68

Active carrier proteins use energy to carry passive carrier proteins into cells.

Question 69

Protein-lined tunnels that span the small intercellular space separating adjacent cells and that allow the rapid and direct passage of ions and small molecules,including signaling molecules,are called ________.

Question 70

Channel proteins require energy for transporting molecules across the plasma membrane.

Question 71

The signaling molecules that interact with cell surface receptors cannot cross the plasma membrane and would generally be classified as large and/or________.

Question 72

Active carrier proteins are not found in the same cells as passive carrier proteins.

Question 73

Channel proteins provide a means for large,________ molecules to move across the plasma membrane without an expenditure of energy.

Question 74

Even though the concentration of water in a cell remains constant in an isotonic solution,the random movement of water molecules during ________ requires that water be constantly moving in both directions across the plasma membrane.

Question 75

Several types of lipoproteins exist;the best balance for cardiovascular health is achieved with ________ amount of LDL and ________ amount of HDL.

Question 76

After eating a meal high in carbohydrates,the pancreas begins releasing the hormone insulin by the process of ________.

Question 77

When the solute concentration outside a cell is equal to the solute concentration inside the cell,the cell is in a(n)________ solution.

Question 78

Passive carrier molecules often require active carrier proteins to provide amino acids for transport.

Question 79

Receptors in target cells can be located in the plasma membrane,the cytosol,or the ________.

Question 80

Cells that experience high mechanical stress,like heart cells,typically connect to one another using a(n)________ junction,allowing the stress to be distributed to a larger area.