Deck 7: Cell Membranes, Transport, and Communication

Question 1

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 1

C

Question 2

The figure below 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.

Answer 2

C

Question 3

The arrows in the figure below 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 permeable.

Answer 3

A

Question 4

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

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 has ceased once the equilibrium was established.
D)None of the above statements describe the equilibrium shown in the illustration.

Question 5

All movement, including that of diffusing molecules, requires a small expenditure of energy; what is the source of the energy that makes diffusion across the cell membrane possible?

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.

Question 6

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 7

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

A)less concentrated (hypotonic).
B)more concentrated (hypertonic).
C)equally concentrated (isotonic).
D)The answer cannot be determined from the information given.

Question 8

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

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

Question 9

The concentration of glucose inside of a cell is higher than the concentration outside of 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 10

Active transport

A)moves substances out of but not into cells.
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 11

You observe a cell in a solution swelling until it bursts. You have seen an instance of osmosis in a(n)

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

Question 12

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

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

Question 13

Which of the following could not easily diffuse across a plasma membrane?

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

Question 14

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 for specific solutes to diffuse through.
D)change shape upon binding to specific external molecules and then release the molecule on the other side of the membrane.

Question 15

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 16

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 17

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

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

Question 18

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 19

The figure below illustrates a plasma membrane.
Which solute in the figure is crossing the membrane using simple diffusion?

A)Ca2+
B)Na+
C)K+
D)H2O

Question 20

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 21

After a steroid 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 22

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 23

People are often warned to watch their blood cholesterol level to be sure it does not become too high. In fact, some people do not eat any cholesterol-containing foods at all. Even though we associate elevated cholesterol levels with a risk of heart attack and stroke, why does the body make some cholesterol even if none is eaten?

A)Cholesterol is the basis of all steroid hormones in the body.
B)Cholesterol is used by the mitochondria for cellular respiration.
C)Cholesterol is a short-range signaling molecule that does not last long in the body.
D)Cholesterol is a key component of DNA.

Question 24

Cell surface receptors of chemical messages are made of

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

Question 25

Objects suspended in the extracellular fluid can cross the plasma membrane and enter a cell by

A)pinocytosis.
B)receptor-mediated endocytosis.
C)phagocytosis.
D)all of the above

Question 26

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

A)Each molecule is unable to cross the membrane, but 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 27

To coordinate the contraction of the numerous muscle cells that form the heart, signals must travel rapidly between muscle cells. In order 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 28

You observe a vesicle moving toward the plasma membrane from the inside of 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 29

All steroid hormones are hydrophobic. Where would you expect the receptor proteins for these hormones to be located?

A)in the hydrophobic portion of the cell membrane
B)in the hydrophilic portion of the cell membrane
C)in the cytoplasm of a cell
D)in the extracellular matrix

Question 30

Which of the following are found in plants?

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

Question 31

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 32

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 33

Animal cells are attached to neighboring cells by

A)their extracellular matrix.
B)gap junctions.
C)tight junctions.
D)all of the above

Question 34

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 35

In the flowchart below summarizing membrane transport, both active and facilitated transports terminate at separate carrier proteins; explain 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 36

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

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

Question 37

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 38

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)Any of the above is a reasonable explanation.

Question 39

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 40

All steroid hormones are derived from

A)cholesterol.
B)progesterone.
C)testosterone.
D)adrenaline.

Question 41

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 42

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 43

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

Question 44

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 45

Channel proteins provide a means for large ____________________ [hydrophobic or hydrophilic] molecules to move across the plasma membrane.

Question 46

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

Question 47

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 cardio-stimulatory 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 48

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 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 49

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

Question 50

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 51

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

A)Lipids alone have low 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 liver for disposal or modification.
D)all of the above

Question 52

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 53

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

Question 54

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

A)auxin
B)insulin
C)adrenalin
D)acetylcholine

Question 55

Why do some hormones, like thyroxin, affect most or all body cells while others only affect a single organ or type of cell?

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

Question 56

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 57

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

Question 58

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)excessive production by the liver
C)reduced acceptance of cholesterol by body cells
D)all of the above

Question 59

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 60

The concentration of solutes is higher within the mitochondria than it is in the cytosol. The cytosol is ____________________ [hypertonic, hypotonic, or isotonic] to the inside of the mitochondrion.

Question 61

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.

Question 62

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 63

During ____________________ endocytosis, specific substances interact with proteins located on the plasma membrane of the cell.

Question 64

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

Question 65

The viscous coating found around most animal cells is called the extracellular ____________________.

Question 66

Gap junctions allow large molecules to move from cell to cell.

Question 67

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

Question 68

Plasmodesmata are not found in animal cells.

Question 69

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

Question 70

Active carrier proteins can transfer molecules into areas of higher concentration.

Question 71

Hydrophilic signaling molecules interact with cells by interacting with cell surface ____________________.

Question 72

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

Question 73

Osmoregulation refers to balancing water concentrations in organisms and cells.

Question 74

Cells suspended in a hypertonic solution will lose water.

Question 75

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

Question 76

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

Question 77

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

Question 78

Tight junctions prevent the movement of the extracellular matrix between cells.

Question 79

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

Question 80

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