WorksheetsPhysiology 1: Chương 4: Vận chuyển các chất qua màng tế bào
Total questions: 74
Worksheet time: 1hrs 14mins
Which of the following statements regarding the structure and function of cell membranes is correct?
The phospholipid bilayer is arranged so that the hydrophilic heads of the phospholipid molecule face the extra- and intracellular fluids.
Some proteins integrated into the membrane serve as channels for the passage of nonpolar molecules through the membrane.
Peripheral membrane proteins function as channels associated with transport of ions through the
membrane.
Cholesterol molecules function to transport ions from one side of the plasma membrane to the other.
The plasma membrane is a layer of phospholipid molecules with their hyrophilic head groups in contact with the extracellular solution and the hydrophobic tail groups in contact with the intracellular solution.
Which is TRUE regarding diffusion?
It depends upon the random motion of molecules.
It results in net movement of molecules from regions of low concentration to regions of high concentration.
It is the principle mechanism by which molecules are moved over large distances in the body.
It requires energy in the form of ATP.
It requires integral membrane proteins to occur.
A solute, X, is placed in compartment A of a two compartment container and allowed to diffuse to
compartment B and attain diffusion equilibrium. At that point in time,
There will be no further movement of any solute molecules between compartments.
Solutes will be moving in both directions equally.
Solutes will only continue to move from A to B.
Solutes will only continue to move from B to A.
The concentration in compartment B will be much higher than that in compartment A.
Which of the following statements regarding the diffusion of a nonpolar solute X across a cell membrane is correct?
At equilibrium the net flux of X across the cell membrane is zero
At equilibrium, X will cease moving across the cell membrane
Solute X will be unable to reach equilibrium because it is nonpolar
Solute X will reach equilibrium, but the concentration will be much higher on the inside of the cell because of the smaller volume
Which of the following would decrease the net flux of a penetrating solute into a cell?
Which of the following would decrease the net flux of a penetrating solute into a cell?
Increasing the permeability constant for that solute
Decreasing the temperature
Increasing the concentration of the solute in the extracellular fluid
Increasing the area of the cell membrane
Decreasing the thickness of the membrane
Equal amounts of two solutes, A and B, are placed into the same beaker of water at the same time.
Solute A reaches diffusion equilibrium faster than solute B. What is the most likely explanation for this
observation?
The temperature was greater for solute A than solute B
The concentration gradient for A was greater than B
Solute A is smaller than solute B
Solute A traveled a shorter distance than solute B
Solute B is more soluble in water than solute A
In general, polar molecules diffuse more rapidly through the lipid bilayer part of cell membranes than do
nonpolar molecules. This statement is:
True
False, because polar molecules diffuse through less rapidly because the bilayer is polar throughout its
width.
False, because polar molecules diffuse through less rapidly because the bilayer is nonpolar throughout
its width.
False, because nonpolar molecules diffuse through more rapidly because much of the bilayer is
nonpolar.
False, because the rate of diffusion of nonpolar and polar molecules through the bilayer is essentially the
same as long as the molecules are the same size.
The permeability of the plasma membrane to mineral ions:
Is not influenced by channels formed by proteins
Is the same in all cell types
Is affected by differences in electrical charge on the two sides of the membrane
Is zero in all living cells
Is only possible because of the hydrophobic interior of the lipid bilayer
Ion channels in cell membranes:
Are nonspecific.
Are not affected by differences in electrical potential across the membrane.
May open in response to binding a ligand.
Only allow ions to move from the extracellular fluid into the cell.
Only allow ions to move from the intracellular fluid out of the cell.
Which is TRUE about mediated transport across cell membranes?
It refers to the movement of ions through protein channels
It refers both to simple diffusion and to the active transport of molecules
It is characterized by saturable carriers and a maximum velocity of transport
As the concentration gradient across a membrane increases, the transport rate always increases
It is nonspecific; any transporter can transport any molecule across the cell membrane.
Which is TRUE about mediated transport of substances across cell membranes?
It involves a specific membrane protein that functions as a carrier molecule
It always involves the movement of substances against a concentration gradient
It is always directly coupled to the splitting of ATP molecules
There is no limit to how fast it can occur as the concentration gradient becomes larger.
It is the main mechanism for transporting hydrophobic molecules across membranes.
Which of the following is a feature that distinguishes active transport from facilitated diffusion?
Saturation of transport rate
Requirement for a carrier molecule
Carrier molecules have specificity
Presence of a transport maximum
Requirement for metabolic energy
Which is true regarding the mediated transport of a substance across a plasma membrane?
It depends upon the binding of that substance to a specific site on the membrane protein.
It depends upon movement of proteins from one side of the membrane to the other.
It always increases in direct proportion to the increasing concentration of the substance on one side of the membrane.
Both "depends upon the binding of that substance to a specific site on the membrane protein" and "depends upon movement of proteins from one side of the membrane to the other" are correct.
All of the choices are correct
Which is a form of cellular transport that involves the movement of molecules into cells without passing through the plasma membrane's structural matrix?
Diffusion
Osmosis
Facilitated diffusion
Endocytosis
Apoptosis
By what transport mechanism does glucose enter most cells?
Diffusion through the lipid bilayer
Primary active transport
Secondary active transport
Diffusion through a protein channel
Facilitated diffusion
What is the best description of a secondary active transport process that cotransports an amino acid with Na+?
Both Na+ and the amino acid bind on the side of the membrane where the Na+ concentration is lowest, and undergo net movement to the other side of the membrane.
Na+ and the amino acid bind to opposite sides of the membrane, and Na+ undergoes net transport from the side of the membrane with higher Na+ concentration toward the side with lower concentration, while the amino acid moves in the opposite direction.
Both Na+ and the amino acid bind on the side of the membrane where the Na+ concentration is higher, and both are transported to the side of the membrane where the Na+ concentration is lower.
Both Na+ and the amino acid bind to the side of the membrane where the amino acid concentration is highest and are transported toward the side of the membrane where the amino acid concentration is lower.
Na+ and the amino acid bind to opposite sides of the membrane, and the amino acid undergoes net transport from the side of the membrane with lower Na+ concentration to the side of the membrane where the Na+ concentration is higher.
1. Which of the following statements about the Na+ K+ ATPase pump is FALSE?
It transports Na+ out of cells and K+ into cells.
It binds to, and hydrolyzes, ATP
It is constantly active in all cells
Its activity requires the expenditure of metabolic energy
It transports Na+ and K+ in a 1:1 ratio
A cell is placed into a 1 millimolar solution of substance X and over time you witness the concentration of X inside the cell increase to 5 milimolar. What is the best explanation for this observation?
X is moving into the cell by simple diffusion
X is moving into the cell by diffusion through a protein channel
X is moving into the cell by facilitated diffusion
X is moving into the cell by primary active transport
Water is leaving the cell by osmosis
If the ATP-generating mechanisms in a cell are poisoned and the cell depletes its ATP reserves, which
would occur first?
Primary active transport of molecules would cease
Secondary active transport of molecules would cease.
Facilitated diffusion of molecules would cease
Ion concentration gradients would reach equilibrium across the cell membrane
All transport processes would cease immediately when the ATP was depleted
"Osmosis" refers to the movement of what substance across semipermeable membranes?
Glucose
Charged particles
Lipid molecules
Water
Solutes
If pure water and a solution containing a nonpenetrating solute are separated by a membrane that is permeable only to water, what would occur?
Water will diffuse by osmosis until the water concentrations in the two compartments become equal.
Water will diffuse by osmosis until all of the the water is on the same side as the solute.
Water will diffuse by osmosis toward the side with the solute, until stopped by opposing hydrostatic pressure.
No movement will occur between the compartments.
Water will diffuse by osmosis away from the side with the solute, until stopped by hydrostatic pressure.
If all other conditions remain the same and the concentration of a nonpenetrating solute increases inside a cell, which is most likely to occur?
Water will tend to enter the cell because the interior has an increased osmolarity.
Water will tend to leave the cell because the interior has an increased osmolarity.
Water will tend to enter the cell because the interior has a decreased osmolarity.
Water will tend to leave the cell because the interior has a decreased osmolarity.
The solute will diffuse across the membrane until its concentration is equal on both sides of the
membrane.
What will happen if a normal cell is placed in a hypotonic solution?
It will swell in size.
It will shrink in size.
It will stay the same size.
The result can't be predicted.
What will happen if a normal cell is placed in a hyperosmotic solution?
It will swell in size.
It will shrink in size.
It will stay the same size.
It may swell, shrink, or stay the same size, depending upon the concentration of penetrating and nonpenetrating solutes in the solution.
If a normal cell is placed into an unknown solution and it shrinks, what can be concluded about the unknown solution?
Its nonpenetrating solute concentration is greater than that of a normal cell.
Its nonpenetrating solute concentration is less than that of a normal cell.
Its nonpenetrating solute concentration is equal to that of a normal cell.
Its penetrating solute concentration is less than that of a normal cell.
Its penetrating solute concentration is greater than that of a normal cell.
Why do solutions for injection or infusion into people with low blood volume normally contain 150 mM NaCl?
This is a hypotonic solution, which will cause water movement into dehydrated blood cells.
This is an isotonic solution, and the water in it will follow Na and Cl into the the intracellular fluid compartment.
This is a hypertonic solution, which will raise the blood volume and pressure more rapidly than an isotonic solution would.
This is an isotonic solution, and NaCl will keep the added volume in the extracellular fluid compartment.
NaCl are penetrating solutes, which will get them more quickly into blood cells to increase their volume.
Which of these is an example of a hypertonic solution?
200 mM NaCl
300 mM glucose
100 mM MgCl2
400 mM urea
100 mM NaCl
Which of the following solutions is not isotonic to human cells?
150 mM NaCl
300 mM urea
100 mM MgCl2
300 mOsm NaCl
Regarding the tonicity and osmolarity of solutions, which of the following statements is not true?
The term "tonicity" refers to the effect that a solution has on the degree of stretch or shrinking of the cell membrane.
The term "osmolarity" refers to the osmotic properties of a solution, regardless of its tonicity.
Isotonic solutions are always isoosmotic.
Hypoosmotic solutions are always hypotonic.
Hypertonic solutions are always hyperosmotic.
Which of the following statements regarding endocytosis and exocytosis is correct?
Endocytosis is a method by which large molecules may be secreted from a cell.
Exocytosis is a method by which large molecules may be secreted from a cell.
Pinocytosis is a form of endocytosis; phagocytosis is a type of exocytosis.
Pinocytosis is a form of exocytosis; phagocytosis is a type of endocytosis.
Pinocytosis and phagocytosis are both types of exocytosis.
Which form of endocytosis is nonspecific, in that it occurs by the formation of an invagination of the plasma membrane, which then fills with interstitial fluid of the immediate area?
Active transport
Hyperosmotic vesicular entrapment
Phagocytosis
Pinocytosis
Hydrosmosis
What type of cellular transport involves the cytosolic protein clathrin?
Exocytosis
Receptor-mediated endocytosis
Primary active transport
Secondary active transport
Pinocytosis
What process lowers blood plasma levels of cholesterol-containing lipoproteins?
Second messenger-activated, sterol transgenesis
Hydrophobic phagocytosis
Simple, transcellular membrane diffusion
Na+ gradient – dependent, secondary active transport
Clathrin-dependent, receptor-mediated endocytosis
Once formed inside of the cell, most endocytic vesicles will fuse with which organelle for sorting?
Endoplasmic reticulum
Golgi apparatus
Endosome
Nucleus
Mitochondria
At any given time it is possible to see endocytotic vesicles docked to intracellular organelles such as
those which may receive their contents for modification, synthesis, packaging, and then release. Which
organelle would be most likely to be involved in this process as a destination for a transport vesicle
formed for this purpose along the plasma membrane?
Golgi apparatus
Peroxisome
Lysosome
Mitochondrion
Ribosome
Which of the following statements about epithelial cells and epithelial transport is NOT correct?
Epithelial cell membranes express different transport proteins on different cell surfaces.
Epithelial cells lining the small intestine have Na, K-ATPase pumps only in their basolateral membranes.
The plasma membrane of epithelial cells that faces the inside of a hollow or fluid-filled chamber in the body is called the basolateral membrane.
The pathway taken by substances that flow between epithelial cells is called the paracellular pathway.
When substances cross epithelial barriers by going through the cell membranes and cytosol, it is called the transcellular pathway.
Which lists the epithelial cell barrier compartments in the order of the typical Na+ concentrations, from highest to lowest?
Intracellular, lumen side, blood side
Blood side, lumen side, intracellular
Blood side, intracellular, lumen side
Lumen side, intracellular, blood side
Lumen side, blood side, intracellular
What is the most common transport mechanism by which glucose and other organic solutes cross the luminal membrane of an epithelial cell layer?
Secondary active cotransport with Na+
Glucose ATPase pump
Facilitated diffusion
Simple diffusion through the paracellular pathway
Through an ion channel
The greater the concentration difference of a substance between two volumes separated by a permeable
membrane, the lesser the magnitude of the net flux of the substance.
(a)
All other factors being equal, the rate of diffusion across a permeable surface will be greater for small molecules than for larger ones.
(a)
Molecules increase their rate of diffusion as temperature increases.
(a)
In general, polar molecules diffuse more rapidly across cell membranes than do nonpolar molecules.
(a)
The component of the plasma membrane that acts as a selective barrier to diffusion of polar molecules is
the integral proteins.
(a)
Although permeability to mineral ions does not vary much from one cell to another, different cells vary
considerably in their permeability to nonpolar molecules.
(a)
Specific proteins in the membranes mediate movement of lipid-soluble molecules into cells.
(a)
Integral membrane proteins can form channels through which ions such as Na+ and K+ can diffuse
(a)
Mediated transport is required in order for glucose, amino acids, and fatty acids to pass into cells because
none of these substances can diffuse through plasma membranes.
(a)
In active transport, the affinity of any given binding site for the molecule to be transported changes as the
site goes from facing one side of the membrane to facing the other side.
(a)
The final equilibrium state reached by a molecule that enters a cell by facilitated diffusion is the same as
that for a molecule that enters the cell by diffusion.
(a)
The Na/K ATPase pump is an enzyme that phosphorylates itself.
(a)
In most of the cells in the body there is an electrical difference such that the inside of cells is positive with
respect to the outside.
(a)
The concentration of calcium in the cytosol of most resting cells is very much lower than the
concentration of extracellular calcium.
(a)
The concentration of calcium in the cytosol of most resting cells is very much lower than the concentration of extracellular calcium.
(a)
The Na+/K+-ATPase carrier transports sodium ions out of cells and potassium ions into cells on a one-to-one basis.
(a)
Active transport, facilitated diffusion and osmosis all directly require the expenditure of metabolic energy.
(a)
Both primary and secondary active transport require the expenditure of metabolic energy.
(a)
Adding one mole of NaCl to one liter of water will lower the water concentration twice as much as adding one mole of glucose.
(a)
Adding one gram of NaCl to one liter of water will lower the water concentration twice as much as adding one gram of glucose.
(a)
The higher the osmolarity of a solution, the higher the concentration of water in it.
(a)
The intracellular concentration of water in the cells of the body is normally the same as the extracellular concentration of water.
(a)
If a cell were placed in a solution of 0.15 M NaCl, it would shrink.
(a)
In the body, Na+ ions behave as if they are nonpenetrating solutes because they are actively transported out of cells
(a)
In the body, K+ ions behave as if they are penetrating solutes because they are actively transported into
cells.
(a)
The fate of all endocytotic vesicles is digestion of their contents by lysosomal enzymes.
(a)
A portion of a cell's plasma membrane is removed during endocytosis.
(a)
Endocytosis of any kind requires metabolic energy.
(a)
Most cells can perform pinocytosis, but only a few kinds can perform phagocytosis.
(a)
Phagocytic leukocytes use phagocytosis to engulf foreign bacteria and destroy them within ribosomes.
(a)
Pinocytosis is a method by which molecules can leave cells whose membranes are impermeable to the molecules.
(a)
The clathrin protein involved in carrying out receptor mediated transport remain with an endosome as it moves deep within the cell and is degraded entirely along with the ingested internal contents
(a)
The luminal side of an epithelial cell is also known as the basolateral side.
(a)
The plasma membranes of epithelial cells facing the lumen of hollow organs or tubes have the same
transport proteins as the plasma membranes that face the interstitial fluid.
(a)
Most organic solutes cross epithelial membranes by simple diffusion on the lumen side followed by active transport across the blood side of the membrane.
(a)
Net movement of solute across an epithelium that is permeable to water is always accompanied by movement of water in the opposite direction.
(a)
