Ch. 4 - Movement of Solutes and Water Across Cell Membranes

A solution contains 5 mol of urea, and 10 mol of sodium chloride. What is its osmolarity? A.) 5 Osm B.) 30 Osm C.) 7.5 Osm D.) 15 Osm E.) 25 Osm

25 Osm

In the Na/K-ATPase pump, ________________(how many?) ions of sodium are transported and _________________(how many?) ions of potassium are transported in each cycle.

3, 2

Rank the three fluid spaces from the lowest to the highest glucose concentration during the process of transepithelial transport of glucose: Extracellular concentration Lumen concentration Intracellular concentration

1.) Lumen concentration 2.) Extracellular concentration 3.) Intracellular concentration

List the following in most logical order of cause and effect: The Na/K-ATPase pump moves Na out of the cell into the interstitial fluid. Water moves from the lumen to the interstitial fluid down its concentration gradient. Na moves from the lumen into the cell down its concentration gradient.

1.) The Na/K-ATPase pump moves Na out of the cell into the interstitial fluid. 2.) Na moves from the lumen into the cell down its concentration gradient. 3.) Water moves from the lumen to the interstitial fluid down its concentration gradient.

What is the direction of net flux through the protein channel?

High to low concentration (Diffusion).

T/F: The time for a substance to reach diffusion equilibrium between two regions within a fluid compartment will increase in linear proportion to the distance between the two regions.

FALSE (moves to the square of the distance)

If 300 millimoles of NaCl are dissolved in 1 Liter of water, how would you describe the osmolarity of the resting membrane? A.) Isoosmotic B.) Hypoosmotic C.) Hyperosmotic

C.) Hyperosmotic

The main barrier that limits the diffusion of polar molecules across a plasma membrane is the _______________.

hydrophobic core of the membrane (ions are insoluble in this fluid)

The difference in electrical charge between the inside and outside of a cell membrane is known as the ____________.

membrane potential

The small electrical potential differences observed in living cells is generally reported in units of _____________________.

millivolts

The lipid bilayer is more permeable to which types of molecules?

Hydrophobic, non-polar, lipid soluble

In a typical example of secondary active transport, the energy required for the movement of a solute across a membrane against its concentration gradient is most directly obtained from ______________.

movement of another solute like sodium ions down its concentration gradient

Ions are able to cross the cell membrane by ______________.

moving through channel proteins

The resting membrane potential is a result of the inside of a cell membrane having a slight net excess of ______________ charges and the outside of a cell having a slight net excess of _________________ charges.

negative; positive

A diffusion equilibrium is defines as having been reached when there is ____________________.

no net flux of solute molecules

If the concentration gradient for an ion is inward, while the electrical gradient is outward, which direction would indicate the net flux of the ion?

It will depend on which force is greater.

Which of two factors directly determine the electrochemical gradient acting on a given ion across a cell membrane?

The membrane potential and the concentration for the ion

A solute that cannot across the cell membrane is called a ____________________ (penetrating or nonpenetrating?) solute.

nonpenetrating

Ion channels can usually be in one of two general states (not including inactivation): the _______________ state or the ______________ state.

open, closed.

The unit of measure for the total concentration of solute particles (including all different molecular species) in a solution is _______________.

osmolarity

The net movement of water across a cell membrane is called _________________.

osmosis

Ions move across the cell membranes via ___________________.

active transport, integral membrane proteins

Primary active transport moves molecules across a membrane _____________ (down/against?) a concentration gradient.

against

T/F: GLUT proteins transport lipids across a membrane using active transport.

FALSE

T/F: The energy for simple diffusion comes from ATP.

FALSE

What is the direction of net flux through the lipid bilayer?

High to low concentration. (Diffusion)

What is the direction of net flux for facilitated diffusion?

High to low concentration. (Mediated transport)

If 2 moles of NaCl are added to 1 Liter of pure water, the osmolarity of the final solution would be __________________.

4 Osm (Dissociation of NaCl into two individual ions will make the osmolarity twice the molar concentration).

What is hyperosmotic?

A solution containing a greater concentration of solutes than is found in normal cells.

What is a hypotonic solution?

A solution containing a lower concentration of nonpenetrating solutes than is found in normal cells.

What is a hypoosmotic solution?

A solution containing a lower concentration of total solutes than is found in normal cells.

What is a hypertonic solution?

A solution containing of nonpenetrating solutes than is found in normal cells.

What is a isotonic solution?

A solution containing the same concentration of nonpenetrating solutes than is found in normal cells.

What is isosmotic solution?

A solution containing the same total concentration of solutes as found in normal cells.

Primary active transport and secondary active transport are similar in that they both _______________________. A.) exhibit specificity B.) use a transporter protein C.) can transport a molecule from an area of low concentration to an area of high concentration D.) directly require ATP for transport

A, B, & C

Which solution would have the highest osmolarity? A.) 2 moles of MgCl2 dissolved in 1 Liter of water B.) 2 moles of NaCl dissolved in 1 Liter of water C.) 2 moles of glucose dissolved in 1 Liter of water D.) 5 moles of glucose dissolved in 1 Liter of water

A.) 2 moles of MgCl dissolved in 1 Liter of water

Which characteristics are common to both protein-mediated transport and ion-channel diffusion? A.) Both show chemical specificity B.) Both change conformation each time a molecule or ion is transported C.) Both involve integral membrane proteins

A.) Both show chemical specificity C.) Both involve integral membrane proteins

Which of the major ions are normally more concentrated in the extracellular fluid than in the intracellular fluid when a cell is at rest? A.) Chloride B.) Potassium C.) Bicarbonate D.) Calcium E.) Magnesium F.) Sodium

A.) Chloride C.) Bicarbonate D.) Calcium F.) Sodium

Choose the terms that mean two different molecules are transported together in the same direction. A.) Cotransport B.) Antiport C.) Symport D.) Countertransport

A.) Cotransport & C.) Symport

Which of the transport mechanisms below display saturation? A.) Facilitated diffusion B.) Simple diffusion C.) Secondary active transport D.) Primary active transport

A.) Facilitated diffusion C.) Secondary active transport D.) Primary active transport

If 300 millimoles of NaCl are dissolved in 1 liter of water, how would you describe the osmolarity of the resulting solution? A.) Hyperosmotic B.) Hypoosmotic C.) Isoosmotic

A.) Hyperosmotic

Red blood cells are placed into a solution of sodium chloride. The cells have an osmolarity of 300 mOsm, and the solution has an osmolarity of 250 mOsm. In which direction would there initially be net water flow? A.) Into the cell B.) No net movement of water would occur C.) Out of the cells

A.) Into the cell

In the Na/K-ATPase pump, which ion binds first to the high affinity sites of the intracellular surface of the protein? A.) Na B.) K

A.) Na

Two 1-Liter compartments are separated by a membrane permeable to water but not to solutes. If 5 moles of NaCl is placed in compartment A, and 5 moles of glucose solution is placed in compartment B, which compartment has a higher osmotic pressure? A.) The osmotic pressure in compartment A is greater B.) The osmotic pressure in both compartments are the same C.) The osmotic pressure in compartment B is greater

A.) The osmotic pressure in compartment A is greater.

Which two of the following are required for net osmosis to occur across a membrane? A.) There is membrane permeability for water B.) There is a gradient of nonpenetrating solute C.) ATP is present D.) There is a temperature gradient

A.) There is membrane permeability for water B.) There is a gradient of nonpenetrating solute

Will a cell placed into a hypertonic solution change size? A.) Yes, it will shrink B.) No, it will not change size. C.) Yes, it will swell.

A.) Yes, it will shrink

You have two containers. One is filled with 500mL of water. The other is filled with the same volume of a 1M sodium chloride solution. Is there a difference in the water concetration? A.) Yes, the water concentration is higher in the container with just water. B.) Yes, the water concentration is higher in the container with the sodium chloride solution. C.) No, the water concentration is the same in both containers.

A.) Yes, the water concentration is higher in the container with just water.

Primary active transport and secondary active transport are similar in that they both ________________________. A.) exhibit specificity B.) can transport a molecule form an area of low concetration to an area of high concentration C.) uses a transporter protein D.) directly require ATP for transport

A.) exhibit specificity B.) can transport a molecule from an area of low concentration to an area of high concentration to an area of high concentration C.) uses a transporter protein

The difference in electrical charge between the inside and outside of a cell membrane is known as the ________________. A.) membrane potential B.) electrochemical gradient C.) equilibrium potential

A.) membrane potential

The electrical component of the electrochemical forces that determines ion flux between the interstitial fluid and intracellular compartments is determined by a cell's ______________. A.) membrane potential B.) size C.) permeability to water D.) chutzpa E.) nucleus

A.) membrane potential

Chloride, potassium, and sodium ions act as _________________ solutes. A.) nonpenetration B.) both penetrating and nonpenetrating C.) penetrating

A.) non penetrating

Based on Fick's diffusion equation, the magnitude of net flux across a membrane is __________________. A.) proportional to the concentration gradient, membrane permeability, and membrane surface area B.) proportional to the membrane permeability, but inversely proportional to the concentration gradient and membrane surface area C.) proportional to the membrane surface area and thickness, but inversely proportional to the concentration gradient D.) proportional to the membrane thickness and surface area

A.) proportional to the concentration gradient, membrane permeability, and membrane surface area

The movement of molecules through an epithelial cell from the lumen of a hollow organ to the interstitial fluid is called ________________. A.) transcellular transport B.) paracellular transport C.) ingestion D.) facilitated diffusion

A.) transcellular transport

Which of the following are examples of carrier-mediated membrane transport?

Active transport, facilitated diffusion

Which of the following are found in both plasma membranes and organelle membranes, and are responsible for the very low calcium concentration in the cytosol of resting cells? A.) Facilitated diffusion transporters that cotransport Ca and H. B.) Ca-ATPase active transport pumps C.) Na/K-ATPase pumps D.) Ion channels for calcium

B.) Ca-ATPase active transport pumps

Which transport mechanisms displays chemical specificity? A.) Simple diffusion B.) Carrier-mediated transport C.) Facilitated diffusion

B.) Carrier-mediated transport C.) Facilitated diffusion

Nutrients in the digestive system are transported across cells into the bloodstream. What is the name for this type of transport? A.) Active transport B.) Epithelial transport C.) Diffusion D.) Compensatory endocytosis E.) Carrier-mediated transport

B.) Epithelial transport

The intracellular fluid of resting cells differs in ionic composition from the extracellular fluid by having a higher concentration of which major ions? A.) Bicarbonate B.) Magnesium C.) Potassium D.) Chloride E.) Calcium F.) Sodium

B.) Magnesium C.) Potassium

Which one of the following characteristics is NOT true of simple diffusion? A.) In simple diffusion, molecules continue to move even after an equilibrium has been reached. B.) Simple diffusion requires ATP C.) Simple diffusion involves thermal energy D.) In simple diffusion, a net flux occurs until the solute concentrations come to an equilibrium E.) Simple diffusion involves a net flux from an area of higher concentration to an area of lower concentration

B.) Simple diffusion requires ATP

A 1M glucose solution is placed in compartment 1, and a 5M KCl solution is placed in compartment 2. The compartments are non-expandable, and are separated by a membrane that is permeable to water, KCl, and glucose. After equilibration, which compartment will have the greater osmotic pressure? A.) The osmotic pressure in compartment 2 will be greater B.) There will be no difference in osmotic pressure between the two compartments C.) The osmotic pressure in compartment 1 will be greater

B.) There will be no difference in osmotic pressure between the two compartments

A 2 mOsM solution containing K and Cl is placed in compartment 1, and a 2 mOsM glucose solution is placed in compartment 2. The compartments are separated by a membrane that is permeable to water, but impermeable to K, Cl, and glucose. What would be the net movement of water in this experiment? A.) From compartment 1 to compartment 2 B.) There would be no net movement of water. C.) From compartment 2 to compartment 1.

B.) There would be no net movement of water.

When crossing an epithelial cell layer by the transcellular route, Na moves across the luminal membrane ________________, and it moves across the basolateral membrane _________________. A.) against its concentration gradient; against its concentration gradient B.) down its concentration gradient; against its concentration gradient C.) down its concetration gradient; down its concentration gradient D.) against its concentration gradient; down its concentration gradient

B.) down its concentration gradient; against its concentration gradient

Simple diffusion occurs when solutes _________________. A.) move from an area of lower to higher concentration B.) move randomly due to thermal energy C.) move down a concentration gradient D.) move from an area of higher to lower concentration

B.) move randomly due to thermal energy C.) move down a concentration gradient D.) move from an area of higher to lower concentration

Paracellular transport through an epithelial cell layer is the movement of substances ______________________. A.) across a membrane in two different direction B.) through tight junctions between adjacent cells C.) directly through the cytoplasm of a cell D.) across a cell in a vesicle

B.) through tight junctions between adjacent cells

The fluid within endosomes contains digestive enzymes. What property of these molecules keeps them contained within the organelle? A.) They are lipid soluble B.)They are large and polar

B.)They are large and polar

For carrier-mediated transport system, which of the following would increase the maximum flux of solute? A.) Decreasing the concetration gradient B.) Decreasing the speed of the transport protein's conformational change C.) Increasing the number of transporters in the membrane D.) Increasing the concentration gradient

C.) Increasing the number of transporters in the membrane

The mathematical formula for Fick's diffusion equation is _______________. A.) J=P/(A&*C) B.) J=(P*A)/(C-C) C.) J= P*A*(C-C) D.) J=P&*A&*C E.) J=C/(P&*A) F.) J=(C-C)/(P*A)

C.) J= P*A*(C-C)

If the permeability coefficient is larger, the net flux of a molecule will _______________. A.) be slower B.) not change C.) be faster

C.) be faster

The basolateral membrane of an epithelial cell faces the _______________. A.) inside of a blood vessel B.) inside of the mitochondria C.) interstitial fluid D.) lumen of a hollow organ such as the intestine

C.) interstitial fluid

The force due to the typical resting membrane potential favors the net movement of cations ___________________. A.) neither into nor out of a cell B.) out of a cell C.) into a cell

C.) into a cell

A solution containing 300 mOsm/L of nonpenetrating solutes and 100 mOsm of penetrating solutes would be classified as which two of the following? A.) hypoosmotic B.) hypotonic C.) isotonic D.) isoosmotic E.) hypertonic F.) hyperosmotic

C.) isotonic, F.) hyperosmotic

Fick's diffusion equation characterizes the factors influencing the ____________________. A.) permeability coefficient B.) direction of net flux C.) magnitude of net flux D.) concentration gradient

C.) magnitude of net flux

In the absence of a concentration gradient, resting membrane potential would favor the movement of anions ________________. A.) into the cell B.) neither into nor out of the cell C.) out of the cell

C.) out of the cell

The key difference between primary active transport and secondary active transport is that primary active transport ________________________. A.) transports solutes from areas of low concentration to high concentration B.) involves an integral membrane protein C.) uses ATP directly for transport

C.) uses ATP directly for transport

The key difference between facilitated diffusion and simple diffusion is that facilitated diffusion ______________________. A.) occurs from lower to higher concentration B.) does not saturate C.) uses a transporter

C.) uses a transporter

Net flux is zero when _____________.

Concentrations are equal between the two compartments (equilibrium)

What mechanism is used when molecules need to be moved long distances in the body? A.) Diffusion B.) Active transport C.) Osmosis D.) Bulk flow

D.) Bulk flow (the heart acts as a pump for this)

Which is the best example of carrier-mediated transport? A.) Movement of water through a membrane by osmosis. B.) Diffusion of an oxygen molecule through the plasma membrane. C.) Movement of hormones through the bloodstream bound to plasma proteins. D.) Movement of an amino acid into a cell by an integral membrane protein.

D.) Movement of an amino acid into a cell by an integral membrane protein.

What are the two types of diffusion mechanisms?

Diffusion through lipid bilayer and diffusion through protein channel.

Which of the following is closest to the normal osmolarity of the body fluid compartments? A.) 0-75 mOsm B.) 385-400 mOsm C.) 50-100 mOsm D.) 150-185 mOsm E.) 285-300 mOsm

E.) 285-300 mOsm

When crossing an epithelial cell layer by the transcellular route, Na usually crosses the luminal membrane by ______________, and it crosses the basolateral membrane using _________________. A.) facilitated diffusion; Na/K-ATPase pumps B.) diffusion; secondary active transport C.) Na/K-ATPase pumps; secondary active transport D.) Na/K-ATPase pumps; diffusion E.) secondary active transport; Na/K-ATPase pumps

E.) secondary active transport; Na/K-ATPase pumps

When a substance crosses an epithelial barrier by moving through an epithelial cell, it is said to move via the _______________________. A.) paracellular pathway B.) pinococytotic pathway C.) potocytotic pathway D.) phagocytotic pathway E.) transcellular pathway

E.) transcellular pathway

Ten moles of the salt potassium choride (KCl) are added to one liter of water. What is the water concentration in the solution (in Moles/Liter)? A.) 45.5M B.) 65.5M C.) 10M D.)5M E.) 55.5M F.) 35.5M

F.) 35.5M

What are the three types of mediated transport?

Facilitated diffusion, primary active transport, secondary active transport.

Molecules of substances within solids, liquids, and gases are in constant motion, and the source of energy causing this motion is ___________.

Heat

Which two of the following pass through membranes via open channel proteins?

Ions and water

Which of these are ions? Water K+ Glucose ATP Na+ Ca2+ Cl-

K, Na, Ca, Cl

What is the direction of net flux for primary active transport?

Low to high concentration (Mediated transport).

A membrane's permeability to a molecule depends on the ___________.

Molecule's lipid solubility & molecule's size.

Carrier proteins that directly require the hydrolysis of ATP to function mediate which process?

Primary active transport

Proton pumps hydrolyze ATP to provide the energy to move hydrogen ions against its concentration gradient. This is an example of which type of molecular movement?

Primary active transport

The exchange of oxygen and carbon dioxide gases occurs through which type of transport mechanism?

Simple diffusion

Name two of the following are NOT examples of mediated transport? Simple diffusion Active transport Facilitated diffusion Osmosis

Simple diffusion and osmosis

The Na/K-ATPase pump moves ___________________.

Sodium and potassium against their concentration gradients, using the energy from ATP.

T/F: Diffusion equilibrium between two regions of a solution occurs more rapidly when there is a shorter distance between those regions.

TRUE

T/F: Epithelial transport utilizes the processes of diffusion and mediated transport.

TRUE

T/F: If ATP production in a cell stops, eventually secondary active transport will also stop.

TRUE

T/F: Ion channels provide a direct passage from one side of the membrane to the other.

TRUE

T/F: Molecular movement continues after a diffusion equilibrium has been reached.

TRUE

T/F: Net movement of solute across an epithelium is typically accompanied by a flow of water in the same direction by osmosis.

TRUE

T/F: The diffusion of ions is influenced by the same factors that influence the diffusion of other solutes, plus the electrical forces that act upon them and the presence or lack of ion channels.

TRUE

T/F: The lipid bilayer is highly impermeable to all charged molecules.

TRUE

What are the 4 determinants of the magnitude of the net flux of molecules between two compartments within a solution.

Temperature, concentration gradient, surface area between compartments, and mass of the molecule

Which two factors directly determine the electrochemical gradient acting on a given ion across a cell membrane?

The concentration gradient for the ion & the membrane potential.

Which of the following is LEAST likely to influence the magnitude of the net flux of a molecule between two fluid compartments?

The difference in volume of the compartments.

Ten molecules of solute X are flowing from area A to area B, and 50 molecules are flowing from area B to area A. Which is TRUE about the net flux of solute X?

The net flux is from area B to area A.

Primary active transport is characterized by ___________________.

The requirement for ATP and the movement of molecules against their concentration gradient.

If the electrical force favoring the movement of an ion into a cell is twice as large as a chemical force favoring the movement of the ion out of the cell, which way will the ion move?

There will be a net inward flux.

A cell that is impermeable to solute B is placed into a solution containing a higher concentration of solute B. What can we say about the net flux of solute B?

There will be not net flux of solute B. (Can you explain why? If not, go back to why Active transport and Diffusion differ)

Choose the characteristics of facilitated diffusion. Requires energy in the form of ATP Uses a carrier protein Net flux from higher to lower concentration

Uses a carrier protein and the net flux goes from higher to lower concentration.

Two different terms are used to describe the portion of an epithelial cell membrane that faces a hollow or fluid-filled chamber (in other words, the part that faces away from the interstitial fluid compartment), the ______________ membrane or the _______________ membrane.

apical, luminal

In this figure, the solute is moving _________________.

by diffusion down a concentration gradient

The flux of an uncharged molecule depends on its ________________ gradient.

concentration

The combination of the forces acting on an ion due to the concentration gradient and the membrane potential is known as the __________________ ___________________.

electrochemical gradient

Some ions move across a membrane using ion channel proteins that are open all the time. Others move through voltage-________, ligand-________ or mechanically-_____________ ion channels.

gated (for all three)

An ion channel that opens when a specific chemical binds to the channel is known as a ________________-____________ ion channel.

ligand-gated

Diffusion of polar molecules into and out of cells and organelles is mainly limited by the __________________.

lipid bilayer (Remember, polar molecules are impermeable by the membrane and can only get across by transport)

What is the direction of net flux for secondary active transport?

low to high concentration (mediated transport).

Ion channels that open or close in response to physical deformation (stretching) of the plasma membrane are called __________-gated channels.

mechanically

Cations will _____________ each other.

repel

The property of ion channels to only allow certain ions to pass through them is known as ___________________.

selectivity

The process of __________ occurs when solute molecules move down a concentration gradient due to random molecular motion.

simple diffusion

All cells have a primary active transporter that pumps ________________.

sodium ions out of cells and potassium ions into cells

Flux is defined as ___________________.

the amount of material moving in one direction between two compartments in a given period of time

The osmotic pressure of a solution is defined as ________________.

the pressure that must be applied to the solution to prevent the net flow of water into it

The key difference between facilitated diffusion and simple diffusion is that facilitated diffusion _________________________ A.) uses a transporter B.) involves integral membrane protein

uses a transporter

Ion channels that open or close in response to changes in the membrane potential are called _________-gated channels.

voltage

Ion channels that open or close in response to changes int= the membrane potential are called ___________.

voltage-gated channels