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WorksheetsBIOL 112-Principles of Biology II-Chpt 5-Membrane Transport-TYU
Total questions: 51
Worksheet time: 26mins
Which cell structure allows selective permeability between a cell and its external environment?
endoplasmic reticulum
mitochondria
chloroplasts
the plasma membrane
lysosomes
Which statement about the role of phospholipids in the structure and function of biological membranes is correct?
Phospholipids form a selectively permeable structure.
Phospholipids form a structure in which the hydrophobic portion faces outward.
They are triacylglycerols, which are commonly available in foods.
Phospholipids form a single sheet in water.
Phospholipids are completely insoluble in water.
Which statement about the fluid mosaic model is true?
The fluid aspect of the membrane is due to the behavior of phospholipids, and the mosaic aspect is due to the presence of carbohydrates.
The mosaic aspect of the membrane is due to the glycosylation of inner leaflet phospholipids.
Only phospholipids are capable of moving in the membrane.
The fluid aspect of the membrane describes its structure at normal temperatures, and the mosaic aspect describes the behavior of the membrane as the temperature is lowered.
The fluid aspect of the membrane is due to the lateral and rotational movement of phospholipids, and embedded proteins account for the mosaic aspect.
Under the fluid mosaic model, where in the plasma membrane would cholesterol most likely be found?
wedged between phospholipid molecules in the interior of the membrane
in the interior and on the inside surface, but not on the outside surface
on the inside (cytoplasmic) surface
on the outside (external) surface of the membrane
on either surface of the membrane, but not in the interior of the membrane
Which functional process is not a consequence of the association of proteins with biological membranes?
cell-cell communication
enzymatic activity
cell-cell recognition
intercellular joining
energy, carbon, and nitrogen storage
Which statement is correct concerning carbohydrates associated with the plasma membrane?)
Carbohydrates associated with the plasma membrane are located on both surfaces of the membrane.
Membrane carbohydrates function primarily in cell-cell recognition.
Carbohydrates on the plasma membrane are typically short chains of between two and five monosaccharides.
The carbohydrate composition of most eukaryotic plasma membranes is quite similar.
Carbohydrates are only found associated with the membranes of prokaryotic cells.
Where in the fluid mosaic model of the membrane would carbohydrates be found?
on the outside (external) surface of the membrane
Carbohydrates are rarely associated with plasma membranes.
on both hydrophilic surfaces of the membrane, but not in the hydrophobic interior
in the interior of the membrane
on the inside (cytoplasmic) surface of the membrane
Which statement(s) about the sidedness of the plasma membrane is/are correct?
Every integral membrane protein has a specific orientation in the plasma membrane.
The asymmetrical distribution of membrane proteins, lipids, and carbohydrates across the plasma membrane is determined as the membrane is being constructed.
Parts of proteins that are exposed on the cytoplasmic side of the endoplasmic reticulum are also exposed on the cytoplasmic side of the plasma membrane.
The two lipid layers may differ in specific lipid composition.
All of the choices are correct.
Which molecule is most likely to passively diffuse across the plasma membrane?
carbon dioxide
DNA
sodium ion
hemoglobin
glucose
Which would be least likely to diffuse through a plasma membrane without the help of a transport protein?
a small nonpolar molecule
a large polar molecule
a large nonpolar molecule
dissolved gases such as oxygen or carbon dioxide
All of the choices would easily diffuse through the membrane.
Which structural arrangement of the components in biological membranes is most consistent with membrane’s property of selective permeability?
proteins embedded in two layers of phospholipid
phospholipids sandwiched between two layers of protein
a phospholipid bilayer with proteins scattered on the surfaces of the membranes
proteins sandwiched between two layers of phospholipid
a layer of protein coating a layer of phospholipid
Which statement about passive transport is correct?
Passive transport does not occur in the human body.
Passive transport operates independently of the concentrations of the moving solute.
Passive transport operates independently of diffusion.
In passive transport, solute movement stops when the solute concentration is the same on both sides of the membrane.
Passive transport permits the solute to move in either direction, but the net movement of the population of solute occurs down the concentration gradient of the molecule.
Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __ because ______.
A … its membrane transport proteins will not be saturated
B … the oxygen molecules inside cell B have a higher kinetic energy
A … the diffusion gradient there is shallower
B … the diffusion gradient in cell B is steeper
B … the gradient of oxygen is oriented in the opposite direction compared to cell A
Which statement about diffusion is true?
It always requires integral proteins of the cell membrane.
It is a passive process of a substance across a membrane with no energy investment
It requires expenditure of energy by the cell.
It is very rapid over long distances.
It occurs when molecules move from a region of lower concentration to a region of higher concentration.
The internal solute concentration of a plant cell is about 0.8 M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what total concentration of solutes?
0.4 M
0.8 M
0 M
1.0 M
150 mM.
A single plant cell is placed in an isotonic solution. Salt is then added to the solution. Which would occur fairly quickly as a result of that addition?
The added salt would enter the cell, causing the cell to take up water and swell.
Water would enter the cell by osmosis, and the cell would swell.
The added salt makes the solution hypotonic compared to the cell. Water will enter the cell by osmosis.
Water would leave the cell by osmosis, causing the volume of the cytoplasm to decrease.
There would be no osmotic movement of water in response to the added salt.
Which statement describes some aspect of facilitated diffusion?
Facilitated diffusion requires energy to drive a concentration gradient.
There is only one kind of protein pore for facilitated diffusion.
Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.
Facilitated diffusion is another name for osmosis.
Facilitated diffusion of solutes occurs through phospholipid pores in the membrane.
Which statement is false in regard to facilitated diffusion?
Facilitated diffusion requires the hydrolysis of ATP.
Facilitated diffusion requires a concentration gradient.
Facilitated diffusion can move ions across membranes.
Facilitated diffusion can occur using transport proteins.
Facilitated diffusion can occur through protein channels.
The red blood cell contain about 2% solutes but almost no sucrose or urea. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink most when immersed in which solution?
a hypotonic urea solution
a hypertonic sucrose solution
a hypertonic urea solution
pure water
a hypotonic sucrose solution
Green olives can be preserved in brine, a 30% salt solution. How does this method of preservation prevent microorganisms from growing in the olives?
High salt concentration lowers the pH, thus inhibiting bacterial metabolism.
Bacteria can get energy from the salt.
A 30% salt solution is hypertonic to the bacteria, so they lose too much water and plasmolyze.
A 30% salt solution is isotonic to the bacteria, so they enter dormancy.
Bacterial cells shrivel up in high-salt solutions, causing the cell to burst.
Active transport requires an input of energy and can also generate voltages across membranes. Based on that, which statement is true?
Active transport moves solutes down their concentration gradients and always uses ATP as the source of energy to do this.
Active transport can use ATP as its energy source and ensures that there is no voltage across the cell membrane.
Active transport uses channel proteins and ensures that the interior of the cell is always positive compared to the exterior of the cell.
The sodium/potassium pump hydrolyzes ATP and results in a net charge of +1 outside the cell membrane.
The source of energy for active transport of a solute up its gradient can be ATP or a concentration gradient of a second solute. This second gradient of solutes maintains no net difference in voltage across the membrane
Which correctly states a difference between active transport and facilitated diffusion?
Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot.
Active transport can move solutes in either direction across a membrane, but facilitated diffusion can only move in one direction.
Active transport requires energy from ATP, and facilitated diffusion does not.
Facilitated diffusion involves transport proteins, and active transport does not.
Active transport involves transport proteins, and facilitated diffusion does not.
A cell has a membrane potential of -100 mV (more negative inside than outside) and has 1,000 times more calcium ions outside the cell than inside. Which best describes a mechanism by which Ca2+ enters this cell?
facilitated diffusion of Ca2+ into the cell down its electrochemical gradient
passive diffusion of Ca2+ into the cell down its electrochemical gradient
movement of Ca2+ into the cell through a carrier protein down its electrical gradient
movement of Ca2+ into the cell through an ion channel down its concentration gradient
cotransport of Ca2+ into the cell with Cl-
Which correctly describes a general property of all electrogenic pumps?
It is a cell with a high internal concentration of protons.
It is a cell with an interior that is positively charged relative to the outside of the cell.
It pumps sodium out of the cell and potassium into the cell.
It creates a voltage difference across the membrane.
It can pump a large variety of solutes across a membrane against their concentration gradient.
Which statement about cotransport of solutes across a membrane is correct?
Cotransport involves the hydrolysis of ATP by the transporting protein.
A cotransport protein is most commonly an ion channel.
The sodium-potassium pump is an example of a cotransport protein.
In cotransport, both solutes that are being transported are moving down their chemical gradients.
Cotransport proteins can couple the “downhill” diffusion of the solute to the “uphill” transport of a second substance against its own concentration gradient.
Consider the transport of protons and sucrose into a plant cell by the sucrose-proton cotransport protein. Plant cells continuously produce a proton gradient by using the energy of ATP hydrolysis to pump protons out of the cell. Why, in the absence of sucrose, don't protons move back into the cell through the sucrose-proton cotransport protein?
Protons cannot move through membrane transport proteins.
Protons are freely permeable through the phospholipid bilayer, so no transport protein is needed for protons.
Protons, unlike other substances, do not diffuse down their concentration gradient.
The movement of protons through the cotransport protein cannot occur unless sucrose also moves at the same time.
In the absence of sucrose, the ATP-powered proton pump does not function, so there is no proton gradient.
Which enables a cell to pick up and concentrate a specific kind of molecule?
passive transport
receptor-mediated endocytosis
osmosis
channel proteins
facilitated diffusion
Which process and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane?
active transport and the rough endoplasmic reticulum
receptor-mediated endocytosis and smooth ER and Golgi
flip-flop of phospholipids from one side of the plasma membrane to the other and the Golgi
endocytosis and Golgi
exocytosis and smooth and rough ER
A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. How do these molecules probably enter the cells lining the baby's digestive tract?
active transport
endocytosis
osmosis
passive transport
exocytosis
Which pair correctly matches a membrane transport process to its primary function?
pinocytosis … the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane
phagocytosis … secretion of large particles from the cell by fusion of vesicles with the plasma membrane
osmosis … passive diffusion of water and small solutes across a membrane
exocytosis … the movement of water and solutes out of the cell by passage through the plasma membrane
None of the choices is correct.
When a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane A2. Thromboxane A2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. In this example thromboxane A2 is acting as a ____.
G protein
neurotransmitter
transcription factor
local regulator
protein kinase
Early work on signal transduction and glycogen metabolism by Sutherland indicated that ______.
epinephrine is involved in response to stress
the signal molecule combined directly with a cytosolic enzyme to form an active quaternary structure
the signal molecule did not interact directly with the cytosolic enzyme, but required an intact plasma membrane before the enzyme could be activated
the cell-signaling pathway involves two separate steps: transduction and response
the signal molecule worked equally well with intact or disrupted cells
Testosterone and estrogen are lipid-soluble signal molecules that cross the plasma membrane by simple diffusion. If these molecules can enter all cells, why do only specific cells respond to their presence?
Nontarget cells lack the inactive enzymes that the signal molecules activate.
Nontarget cells possess enzymes that immediately degrade the molecules as they enter the cell.
Nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cell's nucleus.
In nontarget cells, these signal molecules cross the membranes of the endoplasmic reticulum and are captured by vesicles.
The signal molecules diffuse from the cell before an effective concentration can be achieved.
Steroid hormones can enter a cell by simple diffusion. Therefore steroids ______.
directly bind to DNA
do not bind to receptors
are not an example of signaling molecules
do not initiate cell signaling by interacting with a receptor in the plasma membrane
act by phosphorylating DNA
Steroid hormones can enter a cell by simple diffusion. Therefore steroids ___.
move up a concentration and are polar
move up a concentration gradient and are nonpolar
move through a channel, down a gradient, and are nonpolar
move down a concentration gradient and are polar
None of the choices is correct.
Receptors for signal molecules _____.
are never found in the nucleus of a cell
may be found embedded in the plasma membrane, or found within the cytoplasm or nucleus
are only found associated with the plasma membrane
all work via protein kinases
all work by opening ion channels
Testosterone does not affect all cells of the body because _____.
not all cells have cytoplasmic receptors for testosterone
not all cells in the body have membrane receptors for testosterone
it affects only cells that have ion-channel receptors
testosterone cannot cross the plasma membrane
it is a local regulator
Nitric oxide is unusual among animal signal molecules in that it _____.
binds to membrane receptors and cytoplasm receptors
acts by directly binding to DNA
is a gas
enters the cell via a protein channel
activates proteins by removing phosphate
A G protein is active when ____.
it is bound by its ligand and transported to the nucleus
it is phosphorylated by protein kinase
GDP replaces GTP
GTP is bound to it
Ca2+ binds to a G-protein-linked receptor
What event would activate a G protein?
phosphorylation of GTP to GDP
replacement of GDP with GTP
phosphorylation of GDP to GTP
hydrolysis of GTP to GDP
hydrolysis of GDP to GTP
Ras, a small G protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably. Which change to Ras would you expect in a cancer cell?
a mutation in which Ras cannot bind to its GPCR
a mutation that means GDP is constantly bound to Ras
a mutation that leads to Ras being sent to the endomembrane system
a mutation that means Ras cannot bind to GTP
a mutation that means Ras cannot hydrolyze GTP to GDP
The cellular response of a signal pathway that terminates at a transcription factor would be _____.
the synthesis of mRNA
the activation of an inactive enzyme
alteration of the cytoskeleton
a change in the chemical composition of the cytosolic environment
the activation of a metabolic pathway
What did Sutherland discover about glycogen metabolism in liver cells?
The hormone that breaks down glycogen into glucose enters the liver cell.
The hormone epinephrine binds to a specific receptor on the plasma membrane of the liver cell.
A cytoplasmic receptor triggers the signal transduction pathway that produces glucose from glycogen.
Glucagon breaks down glycogen to glucose in liver cells.
Glucose is produced from glycogen when epinephrine binds to a cytoplasmic protein.
The general name for an enzyme that transfers phosphate groups from ATP to a protein is ______.
peptidase
protein phosphatase
protein cyclase
protein kinase
protein dehydrogenase
ATPgammaS is a form of ATP that cannot be hydrolyzed by enzymes. If this compound was introduced to cells so that it replaced the normal ATP present in the cell, which of the following would you predict?
an increase in anabolic cellular reactions
a decrease in phosphorylated proteins in the cell
an increase in cell division
an increase in the synthesis of mRNA
Two of the listed responses would be expected.
What does the addition of a phosphate group do to a protein?
can either activate or inactivate a protein
activates G-protein-linked receptors
always activates a protein
is accomplished by protein phosphatases
always inactivates a protein
The source of phosphate for a phosphorylation cascade is _____.
protein kinase
ATP
cAMP
GTP
protein phosphatase
Second messengers tend to be water-soluble and small. This accounts for their ability to _______.
pass quickly from cell to cell
rapidly cross the plasma membrane
cross the nuclear membrane and interact with DNA
rapidly move throughout the cell by diffusion
move from substrate to substrate during a phosphorylation cascade
cAMP usually directly activates _____.
receptor tyrosine kinases
protein kinase A
phosphodiesterase
G proteins
adenylyl cyclase
A mutation in the active site of adenylyl cyclase that inactivates it would most likely lead to _____.
an increase in the amount of cAMP present in the cell
increased binding of adenylyl cyclase to the G protein that activates it
lower activity of protein kinase A
higher activity of protein kinase A
reduced binding of adenylyl cyclase to protein kinase A
In eukaryotic cells, which is a second messenger that is produced as a response to an external signal such as a hormone?
tRNA
glucose
epinephrine
cyclic AMP
glycogen
