Chapter 4: The Movement of Substances into and out of Cells
Multiple-Choice Questions
1.
Principles of Water Movement; p. 76; easy; ans: e
Water potential is defined as the:
a.
b.
c.
d.
e.
2.
Principles of Water Movement; p. 77; easy; ans: c
The long-distance transport of sap in the phloem is an example of:
a.
b.
c.
d.
e.
3.
–10
–5
0
10
20
Principles of Water Movement; p. 77; difficult; ans: b
In the absence of other factors affecting water potential, water will move FROM a region of ______
TO a region of ______.
a.
b.
c.
d.
e.
5.
simple diffusion.
facilitated diffusion.
pressure-driven bulk flow.
active transport.
exocytosis.
Principles of Water Movement; p. 77; easy; ans: c
What is the water potential, expressed in units of megapascals, of pure water?
a.
b.
c.
d.
e.
4.
tendency of water to enter a cell.
tendency of water to leave a cell.
mechanical energy of water.
kinetic energy of water.
potential energy of water.
low water concentration; high water concentration
low solute concentration; high solute concentration
low water potential; high water potential
low potential energy; high potential energy
low pressure; high pressure
Principles of Water Movement; p. 77; moderate; ans: e
Which of the following could be the water potential of a sucrose solution at atmospheric pressure
and at sea level?
a.
b.
c.
d.
e.
100 MPa
100 bars
10 bars
0 bars
–10 MPa
6.
Principles of Water Movement; pp. 77-78; moderate; ans: b
Suppose a drop of dye is placed in one end of a tank of water. What happens next?
a.
b.
c.
d.
e.
7.
Principles of Water Movement; p. 78; moderate; ans: a
Which of the following statements about diffusion is FALSE?
a.
b.
c.
d.
e.
8.
When the diffusing molecules become evenly distributed, their movement stops.
Each of the diffusing molecules moves randomly and independently of the others.
It is more rapid at higher than at lower temperatures.
It involves the net movement of a substance.
It is more rapid in gases than in liquids.
Cells and Diffusion; p. 78; moderate; ans: c
Which of the following substances is LEAST likely to diffuse across the plasma membrane?
a.
b.
c.
d.
e.
9.
Nothing happens because the molecules are at equilibrium.
The dye molecules and the water molecules move down their respective concentration
gradients.
The dye molecules move from a region of high water potential to a region of low water
potential.
The dye molecules move against a concentration gradient.
The water molecules move by osmosis.
water
a small, uncharged polar molecule
an ion
carbon dioxide
oxygen
Cells and Diffusion; p. 78; difficult; ans: b
Which of the following statements about solute movement in cells is FALSE?
a.
b.
c.
d.
e.
Once a substance is inside a cell, it moves through the cell by diffusion.
Diffusion is an effective way to move substances between distantly separated cells.
Transport of substances within a cell may be speeded up by cytoplasmic streaming.
Metabolic activities help maintain steep concentration gradients between the inside and outside
of the cell.
Within a cell, a substance may be produced in one place and used in another, thus maintaining
an intracellular concentration gradient.
10. Cells and Diffusion; p. 78; moderate; ans: c
Which of the following is the best definition of osmosis?
a.
b.
c.
d.
e.
The net movement of glucose across a selectively permeable membrane.
The net movement of any substance down a solute concentration gradient.
The net movement of water across a selectively permeable membrane.
The net movement of water from a region of high water potential to a region of low water
potential.
The net movement of water from a region of low water potential to a region of high water
potential.
11. Osmosis and Living Organisms; p. 80; moderate; ans: d
Turgor pressure results most directly from:
a.
b.
c.
d.
e.
solutes moving out of a cell by osmosis.
solutes moving into a cell by osmosis.
water moving from one portion of the cytoplasm to another.
water moving into a cell by osmosis.
water moving out of a cell by osmosis.
12. Osmosis and Living Organisms; p. 80; difficult; ans: e
Wall pressure:
a.
b.
c.
d.
e.
is the same as turgor pressure.
develops within a cell and pushes outward against the wall.
develops outside the cell wall and pushes inward against the wall.
is an outwardly directed pressure of the wall.
is an inwardly directed pressure of the wall.
13. Osmosis and Living Organisms; p. 80; easy; ans: d
In plasmolysis:
a.
b.
c.
d.
e.
the vacuole become turgid.
the entire cell becomes turgid.
the cell wall shrivels into the center of the cytoplasm.
the plasma membrane pulls away from the cell wall.
the plasma membrane is pushed against the cell wall.
14. Osmosis and Living Organisms; p. 80; moderate; ans: b
If a plant cell is placed in a solution with a relatively low water potential, the cell will:
a.
b.
c.
d.
e.
swell and perhaps burst.
undergo plasmolysis.
build up turgor pressure.
build up wall pressure.
neither gain nor lose water.
15. Osmosis and Living Organisms; p. 81; easy; ans: c
Wilting results most directly from _______ in plant cells.
a.
b.
c.
d.
e.
increased metabolism
malfunctioning contractile vacuoles
the loss of turgor
defective osmotic pressure
defective membranes
16. Structure of Cellular Membranes; p. 82; easy; ans: e
When botanists speak of a “bilayer,” they are referring to a structure composed entirely of:
a.
b.
c.
d.
e.
carbohydrates.
integral proteins.
lectins.
sterols.
phospholipids.
17. Structure of Cellular Membranes; p. 82; easy; ans: d
The most abundant sterol in the plant cell membrane is:
a.
b.
c.
d.
e.
lectin.
cholesterol.
triglyceride.
stigmasterol.
phospholipid
18. Structure of Cellular Membranes; p. 82; easy; ans: b
The portion of a transmembrane protein embedded in the bilayer is:
a.
b.
c.
d.
e.
hydrophilic.
hydrophobic.
a glycoprotein.
a glycolipid.
a lectin.
19. Structure of Cellular Membranes; p. 82; moderate; ans: d
By definition, all proteins attached to protruding portions of transmembrane proteins are:
a.
b.
c.
d.
e.
transmembrane proteins.
integral proteins.
globular proteins.
peripheral proteins.
glycoproteins.
20. Structure of Cellular Membranes; p. 82; easy; ans: d
Which of the following statements concerning membrane structure is FALSE?
a.
b.
c.
d.
e.
Some proteins are firmly anchored in place.
Some proteins move laterally within the membrane.
Some lipids move laterally within the membrane.
Transmembrane proteins lack hydrophilic sequences.
Peripheral proteins lack hydrophobic sequences.
21. Structure of Cellular Membranes; p. 82; moderate; ans: e
Although membranes were previously described by the “fluid-mosaic” model, recent evidence
suggests that membranes:
a.
b.
c.
d.
e.
have lipids that are more widely dispersed and not grouped.
have proteins that are not organized in functional complexes.
have a smaller proportion of proteins.
have a more constant thickness.
are less fluid.
22. Structure of Cellular Membranes; p. 82; difficult; ans: d
In the plasma membrane, carbohydrates are most likely to be found:
a.
b.
c.
d.
e.
attached to phospholipids in the bilayer.
attached to cholesterol in the bilayer.
attached to a desmotubule in the bilayer.
on the outer membrane surface.
on the inner membrane surface.
23. Structure of Cellular Membranes; p. 82; moderate; ans: c
What is the hypothesized role of carbohydrates in the plasma membrane?
a.
b.
c.
d.
e.
catalyzing chemical reactions
keeping the phospholipid tails aligned
recognizing molecules that interact with the cell
acting as a barrier to the passage of molecules
transporting molecules into the cell
24. Structure of Cellular Membranes; p. 82; easy; ans: a
Most membrane carbohydrates are present in the form of:
a.
b.
c.
d.
e.
glycoproteins.
lectins.
individual glucose molecules.
starch.
disaccharides.
25. Structure of Cellular Membranes; p. 82; difficult; ans: b
The portion of a transmembrane protein that is embedded in the hydrophobic interior of the bilayer is
usually in the form of a(n):
a.
b.
c.
d.
e.
beta pleated sheet.
alpha helix.
alpha helix and beta pleated sheet combined.
extended polypeptide without secondary structure.
folded polypeptide without secondary structure.
26. Structure of Cellular Membranes; pp. 82-83; moderate; ans: d
Which of the following is NOT a function of membrane proteins?
a.
b.
c.
d.
e.
converting energy from one form to another
catalyzing chemical reactions
transporting specific molecules or ions into and out of the cell
making the membrane impermeable
acting as receptors for chemical signals
27. Transport of Solutes across Membranes; p. 83; moderate; ans: e
Small nonpolar molecules, such as O2 and CO2, enter a cell by:
a.
b.
c.
d.
e.
active transport.
osmosis.
facilitated diffusion.
vesicle-mediated transport.
simple diffusion.
28. Transport of Solutes across Membranes; p. 83; difficult; ans: e
A steroid hormone would most likely enter a cell by:
a.
b.
c.
d.
e.
active transport.
osmosis.
facilitated diffusion.
vesicle-mediated transport.
simple diffusion.
29. Transport of Solutes across Membranes; p. 84; easy; ans: e
A “gate” is most directly associated with a:
a.
b.
c.
d.
e.
pinocytosis.
pump.
vesicle
carrier.
channel.
30. Transport of Solutes across Membranes; p. 84; easy; ans: b
An aquaporin is a:
a.
b.
c.
d.
e.
hole in a water molecule.
channel protein for water.
carrier protein for water.
protein that binds water inside the cytosol.
carbohydrate that binds water to prevent bursting of the cell.
31. Transport of Solutes across Membranes; p. 84; easy; ans: e
Aquaporins are found in the plasma membrane and the:
a.
b.
c.
d.
e.
inner mitochondrial membrane only.
inner chloroplast membrane only
tonoplast only.
endoplasmic reticulum only.
the mitochondrial membrane, the chloroplast membrane, the tonoplast, and the ER.
32. Transport of Solutes across Membranes; p. 84; difficult; ans: c
Which of the following statements about an electrochemical gradient is FALSE?
a.
b.
c.
d.
e.
It involves a concentration gradient and the membrane potential.
It involves a concentration gradient and the total electrical gradient.
It is the driving force for the movement of charged and uncharged substances across a
membrane.
Plant cells maintain an electrochemical gradient across the plasma membrane.
Plant cells maintain an electrochemical gradient across the tonoplast.
33. Transport of Solutes across Membranes; p. 84; difficult; ans: a
If the concentration of K+ is higher outside a plant cell than inside, K+ will enter the cell by:
a.
b.
c.
d.
e.
facilitated diffusion through channel proteins.
simple diffusion through channel proteins.
facilitated diffusion via carrier proteins.
active transport through channel proteins.
active transport via carrier proteins.
34. Transport of Solutes across Membranes; p. 85; moderate; ans: d
Symport is a transport system in which the transport of one solute:
a.
b.
c.
d.
e.
occurs via a vesicle.
occurs without the simultaneous transport of another solute.
depends on the transport of another solute in the opposite direction.
depends on the transport of another solute in the same direction.
depends on the opening of a “gate” in the carrier protein.
35. Transport of Solutes across Membranes; p. 85; easy; ans: e
Which of the following processes in plant cell membranes requires ATP?
a.
b.
c.
d.
e.
simple diffusion
facilitated diffusion
osmosis
passive cotransport
active transport
36. Transport of Solutes across Membranes; p. 85; moderate; ans: b
If the concentration of glucose is higher inside a cell than outside, glucose will enter the cell only by:
a.
b.
c.
d.
e.
simple diffusion.
active transport.
facilitated diffusion.
osmosis.
passive cotransport.
37. Transport of Solutes across Membranes; p. 85; difficult; ans: a
In the active transport of sucrose, the secondary active transport system is the:
a.
b.
c.
d.
e.
sucrose-proton symporter.
H+-ATPase.
sucrose uniporter.
proton pump.
sucrose-proton antiporter.
38. Vesicle-Mediated Transport; p. 86; easy; ans: d
Proteins and polysaccharides will most likely enter a cell by:
a.
b.
c.
d.
e.
active transport.
osmosis.
facilitated diffusion.
vesicle-mediated transport.
simple diffusion.
39. Vesicle-Mediated Transport; p. 86; easy; ans: b
A cell that ingests bacteria or cellular debris does so by:
a.
b.
c.
d.
e.
exocytosis.
phagocytosis.
pinocytosis.
receptor-mediated endocytosis.
facilitated diffusion.
40. Vesicle-Mediated Transport; p. 87; easy; ans: e
In receptor-mediated endocytosis, specific receptors for the substances to be transported are localized
in:
a.
b.
c.
d.
e.
the nucleus.
Golgi bodies.
mitochondria.
the cytoplasm.
coated pits.
41. Vesicle-Mediated Transport; p. 87; moderate; ans: b
In receptor-mediated endocytosis, what happens immediately after the substance to be transported
binds to a receptor?
a.
b.
c.
d.
e.
The substance is broken down enzymatically.
The coated pit invaginates to form a coated vesicle.
The receptor releases the substance inside the cell.
The coated vesicle sheds its coat.
The receptor is broken down enzymatically.
42. Cell-to-Cell Communication; pp. 87-88; difficult; ans: c
Which of the following would NOT occur during signal recognition?
a.
b.
c.
d.
e.
The signal molecule binds to a specific receptor on the plasma membrane.
The signal molecule is transported into the cell by endocytosis.
The signal molecule is transported out of the cell by exocytosis.
The signal molecule remains outside the cell.
The signal molecule activates a transmembrane protein.
43. Cell-to-Cell Communication; p. 88; easy; ans: c
Two of the most common second messengers are:
a.
b.
c.
d.
e.
hormones and ATP.
ATP and cyclic AMP.
calcium ions and cyclic AMP.
lectins and calcium ions.
lectins and clathrin.
44. Cell-to-Cell Communication; p. 88; moderate; ans: d
In the signal-transduction pathway involving Ca2+ ions in plants, which of the following occurs
during the transduction step?
a.
b.
c.
d.
e.
The chemical signal binds to the receptor.
The Ca2+-calmodulin complex activates specific enzymes.
Clathrin binds to Ca2+ ions.
Calcium ions are released into the cytosol from the vacuole.
Calcium ions bind to calmodulin.
45. Cell-to-Cell Communication; p. 88; moderate; ans: e
The symplast consists of:
a.
b.
c.
d.
e.
the cell wall continuum.
all the plasma membranes.
all the desmotubules.
all the protoplasts but not their plasmodesmata.
all the protoplasts including their plasmodesmata.
46. Cell-to-Cell Communication; p. 88; easy; ans: b
Primary plasmodesmata are different from secondary plasmodesmata in that primary
plasmodesmata:
a.
b.
c.
d.
e.
are narrow strands of cytoplasm.
are formed during cytokinesis.
are typically branched.
connect the protoplasts of neighboring cells.
may be connected by a cavity in the region of the middle lamella.
47. Cell-to-Cell Communication; p. 88; moderate; ans: d
Which of the following statements concerning the desmotubule is FALSE?
a.
b.
c.
d.
e.
It has the appearance of a tubular strand.
It may contain a central rod.
It is continuous with the endoplasmic of adjacent cells.
It is a main channel for transporting materials.
It is found within a plasmodesma.
48. Cell-to-Cell Communication; p. 88; moderate; ans: a
The cytoplasmic sleeve is the:
a.
b.
c.
d.
e.
cytoplasmic channel involved in symplastic transport through a plasmodesma.
cytoplasm inside the lumen of a desmotubule.
cytoplasm in the cortical area of the protoplast.
cytoplasm inside the endoplasmic reticulum.
extension of the cytoplasm into the cell wall.
49. Cell-to-Cell Communication; pp. 89-90; moderate; ans: e
Which of the following statements concerning plasmodesmata is FALSE?
a.
b.
c.
d.
e.
They can mediate the transport of proteins and RNA.
Their openings can be regulated by actin and myosin..
They serve as paths for electrical signaling.
Their permeability can be controlled by callose.
Their similar symplastic domains cause them to be passive structures.
True-False Questions
1.
Principles of Water Movement; p. 76; easy; ans: T
Water moves from a region where water potential is higher to a region where it is lower.
2.
Principles of Water Movement; p. 78; easy; ans: T
The steeper the concentration gradient, the more rapid the rate of diffusion.
3.
Cells and Diffusion; p. 78; difficult; ans: F
A protein would most likely enter a cell by simple diffusion.
4.
Cells and Diffusion; p. 78; moderate; ans: T
Once inside a cell, an ion will move from one part of the cytoplasm to another by diffusion.
5.
Cells and Diffusion; p. 79; moderate; ans: F
The rate of osmosis is influenced by the size of the solute particle.
6.
Osmosis and Living Organisms; p. 80; easy; ans: T
Turgor pressure is particularly important in the support of nonwoody plants.
7.
Osmosis and Living Organisms; pp. 80–81; difficult; ans: T
When a leaf wilts, the leaf cells most likely have already plasmolyzed.
8.
Structure of Cellular Membranes; p. 82; easy; ans: T
All the membranes of a cell have the same basic structure.
9.
Structure of Cellular Membranes; p. 82; easy; ans: F
Cholesterol is the major sterol in the plasma membrane of plant cells.
10. Structure of Cellular Membranes; p. 82; easy; ans: F
The inner and outer surfaces of a plasma membrane have the same chemical composition.
11. Structure of Cellular Membranes; p. 82; easy; ans: F
In the plasma membrane, proteins can move laterally but lipids cannot.
12. Structure of Cellular Membranes; p. 82; moderate; ans: T
In the plasma membrane, multipass proteins typically span the bilayer as alpha-helices.
13. Transport of Solutes across Membranes; p. 84; easy; ans: F
The transport of solutes by carrier proteins is faster than that by channel proteins.
14. Transport of Solutes across Membranes; p. 84; easy; ans: F
Passive diffusion can occur down a concentration gradient but not down an electrochemical gradient.
15. Transport of Solutes across Membranes; p. 84; moderate; ans: F
Unlike active transport, passive transport across cellular membranes does not require the
participation of transport proteins.
16. Vesicle-Mediated Transport; p. 86; easy; ans: T
Pinocytosis is a form of endocytosis.
17. Vesicle-Mediated Transport; p. 87; moderate; ans: T
Receptor-mediated endocytosis involves the vesicle-mediated transport of specific molecules.
18. Cell-to-Cell Communication; p. 88; easy; ans: F
Typically a second messenger is located on the outside, rather than the inside, of a cell.
19. Cell-to-Cell Communication; p. 88; easy; ans: F
The apoplast consists of all the interconnected protoplasts of the plant body together with their
plasmodesmata.
20. Cell-to-Cell Communication; p. 88; easy; ans: T
Secondary plasmodesmata are formed after cytokinesis.
Essay Questions
1.
Introduction; p. 75; moderate
Discuss the importance of membranes in the life of the cell.
2.
Principles of Water Movement; pp. 76–77, moderate
Compare and contrast bulk flow and simple diffusion.
3.
Principles of Water Movement; p. 78; easy
When diffusing substances reach equilibrium, diffusion ceases but molecular movement continues.
How is this possible?
4.
Osmosis and Living Organisms; pp. 80-81; moderate
Explain the relationship between turgor pressure and plasmolysis. What effects does each have on
the plant?
5.
Structure of Cellular Membranes; p. 82; moderate
Which parts of a transmembrane protein are hydrophilic and which parts are hydrophobic? How does
this arrangement correlate with the hydrophobic and hydrophilic portions of the phospholipid
bilayer?
6.
Structure of Cellular Membranes; p. 82; moderate
List the molecular components of the plant cell plasma membrane, and note briefly the function(s) of
each.
7.
Structure of Cellular Membranes; p. 82; moderate
In what ways is the term “fluid-mosaic” an accurate description of membrane structure? Based on
recent evidence, in what ways is the term inaccurate?
8.
Transport of Solutes across Membranes; pp. 84–85; moderate
Compare and contrast simple diffusion, facilitated diffusion, and active transport.
9.
Vesicle-Mediated Transport; pp. 86–87; moderate
Explain the structural relationship between the surfaces of a coated pit, of a coated vesicle, and of the
plasma membrane, and how this relates to the mechanism of receptor-mediated endocytosis.
10. Cell-to-Cell Communication; pp. 87–88; moderate
Explain the differences between first and second messengers. Discuss how they each are involved in
signal transduction.
11. Cell-to-Cell Communication; pp. 88–90; moderate
Discuss the transport of materials between cells via plasmodesmata.