BIO377 Chapter 4
A solution contains 5 mol of urea, and 10 mol of sodium chloride. What is its osmolarity? (remember that the ions in salts dissociate in solution)
25 Osm
The normal osmolarity of the body fluid compartments is ___-___ mOsm
285-300
Place the steps of the Na+/K+ ATPase pump in order... 1. A conformational change exposes Na+ binding sites to the extracellular fluid, decreasing their affinity and releasing the 3 Na+ ions 2. The new conformation increases the affinity of 2 binding sites for K+ ions, and they bind to 3. In the cytoplasm, 3 Na+ ions bind to 3 binding sites on the carrier protein 4. ATP is hydrolyzed to phosphorylate the protein and ADP is released 5. Binding of K+ results in dephosphorylation of the transporter, returning it to the original shape and releasing the 2 K+ ions inside of the cell
3,4,1,2,5
List the following in most logical order of cause and effect... 1. Water moves from the lumen to the interstitial fluid down its concentration gradient. 2. The Na+/K+ -ATPase pump moves Na+ out of the cell into the interstitial fluid. 3. Na+ moves from the lumen into the cell down its concentration gradient.
2, 3, 1
Rank the three fluid spaces from lowest to highest glucose concentration during the process of transepithelial transport of glucose... 1. Intracellular concentration 2. Lumen concentration 3. Extracellular concentration
2,3,1
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
Ten moles of the salt potassium chloride (KCl) are added to one liter of water. What is the water concentration in moles/liter? Remember KCl dissociates
35.5
If 2 moles of NaCl are added to 1 liter of pure water, the osmolarity of the final solution would be ___.
4 Osm
Carrier proteins that directly require the hydrolysis of ATP to function mediate which process? A. primary active transport B. facilitated diffusion C. primary passive transport D. simple diffusion E. osmosis
A
Liver cells are able to break down glycogen into glucose, thus causing the intracellular glucose concentration to become higher than the extracellular glucose concentration. What happens to facilitated diffusion of glucose under these conditions? A. Facilitated diffusion causes net movement of glucose out of the liver cells. B. Facilitated diffusion of glucose stops until the intracellular concentration drops below that of the extracellular fluid. C. Facilitated diffusion of glucose can only be into the cell, so glucose continues to be transported into the cell against its concentration gradient.
A
The fluid within endosomes contains digestive enzymes. What property of these molecules keeps them contained within the organelle? A. They are large and polar. B. They are lipid soluble.
A
The movement of water through a semipermeable membrane occurs by what mechanism? A. diffusion through aquaporins B. pinocytosis C. active transporter D. facilitated diffusion transporter E. endocytosis
A
Two 1-liter compartments are separated by a membrane permeable to water but not to solutes. If 5 moles of NaCl solution 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
When crossing an epithelial cell layer by the transcellular route, Na+ moves across the luminal membrane _____________, and it moves across the basolateral membrane ____________. A. down its concentration gradient; against its concentration gradient B. against its concentration gradient; down its concentration gradient C. down its concentration gradient; down its concentration gradient D. against its concentration gradient; against its concentration gradient
A
Which of the following is LEAST likely to influence the magnitude of net flux of a molecule between two fluid compartments? A. The difference in volume of the compartments B. The surface area connecting the compartments C. The magnitude of the concentration gradient between compartments D. The temperature E. The mass of the molecule
A
The TWO mechanisms of transporting organic molecules across an epithelial barrier from the lumen to the interstitial fluid includes _________ across the __________ membrane. A. secondary active transport of the organic molecule; apical B. facilitated diffusion of the organic molecule; basolateral C. facilitated diffusion of the organic molecule; luminal D. primary active transport of the organic molecule; apical E. primary active transport of the organic molecule; basolateral
A and B
Select the TWO that are NOT determinants of the magnitude of the net flux of molecules between two compartments within a solution. A. Gravity B. Concentration gradient C. Difference in compartment volumes D. Mass of molecule E. Surface area between compartments F. Temperature
A and C
What are the characteristics of transport through ion channels? A. net flux of ions across the membrane is determined both by concentration and electrical gradients B. ATP is always needed directly for ions to flow across the membrane C. ion channels can be gated between open and closed states D. a transporter protein is needed to move the ions
A and C
Which TWO characteristics are common to both protein-mediated transport and ion-channel diffusion? A. both involve integral membrane proteins B. both change conformation each time a molecule or ion is transported C. both show chemical specificity
A and C
The intracellular fluid of resting cells differs in ionic composition from the extracellular fluid by having a higher concentration of which major ion(s)? A. potassium B. calcium C. bicarbonate D. sodium E. magnesium F. chloride
A and E
Which TWO of the following are examples of carrier-mediated membrane transport? A. active transport B. simple diffusion C. endocytosis D. exocytosis E. facilitated diffusion
A and E
The magnitude of solute flux with mediated-transport systems depends on which factor(s)? (select all that apply) A. solute concentration B. how saturated the binding sites are C. number of transporters present D. diffusion coefficient E. how quickly the transporter changes conformation F. energy source
A, B, C, and E
Simple diffusion occurs when solutes ________. (select all that apply) A. move down a concentration gradient B. move from an area of lower to higher concentration C. move randomly due to thermal energy D. move from an area of higher to lower concentration
A, C, and D
The lipid bilayer is more permeable to which type(s) of molecule(s)? (Select all that apply) A. nonpolar B. water soluble C. hydrophobic D. hydrophilic E. polar F. lipid soluble
A, C, and F
Primary active transport is directly achieved by hydrolysis of _______.
ATP
Ions move across the cell membrane via ____________. (select all that apply) A. simple diffusion directly through the lipid bilayer B. integral membrane proteins C. active transport D. changes in their conformation
B and C
Primary active transport is characterized by _______. (select all that apply) A. an absence of carrier proteins B. the requirement for ATP C. the movement of molecules against their concentration gradient
B and C
Anions will ______ each other A. neither attract nor repel B. repel C. attract
B
In the body, diffusion is useful for movements of solutes __________. A. over distances of several centimeters B. only over distances of cellular dimensions C. over distances of several meters
B
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 500 mOsm. Which direction would water flow? A. Into the cells B. Out of the cells C. No net movement of water occurs
B
Ten molecules of glucose flow from compartment 1 to compartment 2 at the same time that 50 molecules of glucose flow from compartment 2 to compartment 1. What is the most accurate description of this situation? A. net flux of glucose is from compartment 1 to compartment 2 B. glucose flux occurs in both directions. C. glucose flux only occurs from compartment 2 to compartment 1. D. there is no net flux of glucose
B
The Na+/K+ ATPase pump moves __________. A. Na+ against its concentration gradient, using the energy of K+ moving down its concentration gradient B. Na+ and K+ against their concentration gradients, using the energy from ATP C. K+ against its concentration gradient, using the energy of Na+ moving down its concentration gradient. D. Na+ and K+ down their concentration gradients, without the need for energy input.
B
The force due to the typical resting membrane potential favors the net movement of cations __________. A. out of a cell B. into a cell C. neither into nor out of a cell
B
When Na+ and Cl- are ingested _________. A. They remain in the extracellular fluid compartment because with regard to cell membranes they are effectively penetrating solutes. B. They remain in the extracellular fluid compartment, because with regard to cell membranes they are effectively nonpenetrating solutes. C. They distribute evenly between the extracellular and intracellular fluid compartments because they are effectively nonpenetrating solutes. D. They distribute evenly between the extracellular and intracellular fluid compartments because they are effectively penetrating solutes.
B
Which TWO factors directly determine the electrochemical gradient acting on a given ion across a cell membrane? A. presence of gated channels for the ion B. membrane potential C. concentration gradient for the ion D. tonicity of the extracellular fluid E. osmolarity of the extracellular fluid
B and C
Which TWO of the following are NOT examples of mediated transport? A. Active transport B. Simple diffusion C. Osmosis D. Facilitated diffusion
B and C
Which transport mechanism(s) displays chemical specificity? A. simple diffusion B. carrier-mediated transport C. facilitated diffusion
B and C
Which characteristicS of the transport process shown in the figure are NOT also characteristic of facilitated diffusion? A. Conformational change of a transport protein occurs B. There is net movement of solute from an area with low concentration to one with higher concentration C. A membrane-bound transport protein is inolved D. ATP is hydrolyzed
B and D
Which two of the following are required for net osmosis to occur across a membrane? A. there is a temperature gradient B. there is a gradient of nonpenetrating solute C. ATP is present D. there is membrane permeability for water
B and D
Which of the following are NOT major primary active-transport proteins found in most cell membranes? (select all that apply) A. H+/K+-ATPase pumps B. Na+/Cl--ATPase pumps C. Na+/K+-ATPase pumps D. H+-ATPase pumps E. Aquaporins F. Ca++-ATPase pumps
B and E
Primary active transport and secondary active transport are similar in that they both ________. (select all that apply) A. directly require ATP for transport B. exhibit specificity C. can transport a molecule from an area of low concentration to an area of high concentration D. use a transporter protein
B, C, and D
Diffusion of polar molecules across a membrane is mainly limited by the membrane's structure, namely its _________. A. hydrophilic interior B. hydrophobic exterior C. hydrophobic interior D. hydrophilic exterior
C
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. out of the cells B. no net movement of water would occur C. into the cells
C
Secondary active transport _________. A. directly splits ATP to move ions, so if a cell's ATP production stopped, secondary active transport would immediately stop. B. has no dependence on ATP; even if a cell stopped making ATP, secondary active transport would continue. C. depends indirectly on ATP, because it uses gradients created by ATP-driven pumps
C
The exchange of oxygen and carbon dioxide gases occurs through which type of transport mechanism? A. active transport B. facilitated diffusion C. simple diffusion
C
What is the general name for the overall type of transport that moves organic solute X from the lumen side compartment to the blood side compartment? A. exocytosis B. bulk flow C. transepithelial transport D. paracellular transport E. simple diffusion
C
Which two substances can NOT easily diffuse through the plasma membrane? A. lipids B. carbon dioxide C. sodium ions D. oxygen E. steroid hormones F. proteins
C and F
In a beaker containing 1 liter of water, 150 millimoles of NaCl and 100 millimoles of urea are dissolved. What will happen to a normal red blood cell immersed in that solution? A. It will shrink because the solution has an osmolarity of 250 mOsm, and is hypotonic B. It will swell because the solution has only 150 mOsm of nonpenetrating solute C. It will shrink because the solution has a total osmolarity of 400 mOsm D. It will not change in size because the solution has 300 mOsm of nonpenetrating solute E. It will swell because the solution has an osmolarity of 250 mOsm, and is thus hypotonic
D
Which of the following factors influences the net flux of ions across the cell membrane, but does not affect the net flux of nonpolar substances? A. The concentration gradient B. The lipid solubility C. The membrane permeability D. The membrane potential E. The surface area of the membrane
D
Which of the following regarding simple diffusion is FALSE? A. simple diffusion involves thermal energy B. in simple diffusion molecules continue to move even after an equilibrium has been reached C. simple diffusion involves a net flux from an area of higher concentration to an area of lower concentration D. simple diffusion requires ATP E. in simple diffusion, a net flux occurs until the solute concentrations come to an equilibrium
D
Which of the following would increase the time it takes for diffusion equilibrium to be reached between a cell's intracellular fluid and the blood plasma? A. decreasing the mass of the solute that is diffusing B. increasing the surface area of the cell C. increasing the temperature of the blood D. increasing the distance between the cell and the blood stream
D
What condition(s) is(are) necessary for a net flux to occur across a surface that is permeable to a solute? A. Surface must be impermeable to the solvent B. Surface must have ion channels C. Surface must have transporter proteins D. Surface must be permeable to the solute E. Must be a concentration gradient of solute F. ATP must be present
D and E
Solute X flows from an area of higher concentration to an area of lower concentration through the lipid bilayer portion of a cell membrane. This is an example of what type(s) of molecular movement(s)? A. potocytosis B. facilitated diffusion C. osmosis D. primary active transport E. simple diffusion
E
True or false: The greater the osmolarity of a solution, the lower the osmotic pressure of that solution.
True
True or false: 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
Molecules of substances within solids, liquids, and gases are in constant motion and the source of energy causing this motion is ___________.
heat
Type of transport in which two different molecules are transported together in the opposite direction.
antiport
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 (also called the __________ membrane)
apical/luminal
Special channels that allow the movement of water across a membrane.
aquaporins
Movement of an amino acid into a cell by an integral membrane protein is the best example of _____________ transport
carrier-mediated
Ions are able to cross the cell membrane by moving through _________ _______.
channel proteins
Ions require ion channels to move through a membrane because ions are ______
charged
The flux of an uncharged molecule depends on its __________ gradient
concentration
__________ transport happens when nutrients in the digestive system are transported across cells into the bloodstream.
epithelial
GLUT proteins are found in various isomers in different tissues and are specialized for the ________ _________ of glucose
facilitated diffusion
The amount of material moving in one direction between two compartments in a given period of time is called _____.
flux
In a(n) _______ solution the cell will shrink... In a(n) _______ solution the cell will swell... In a(n) _______ solution there will be no change in cell size.
hypertonic/hypotonic/isotonic
An ion channel that opens when a specific chemical binds to the channel is known as a _____-______ ion channel.
ligand-gated
The function of the lipid bilayer in terms of movement of molecules is to ________ movement of polar substances.
limit
Ion channels that open or close in response to physical deformation (stretching) of the plasma membrane are called _________-gated channels
mechanically
The small electrical potential differences observed in living cells is generally reported in units of _________.
millivolts
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 _________ solute cannot cross the cell membrane.
nonpenetrating
Isoosmotic, hypoosmotic, and hyperosmotic all have to do with solutes and isotonic, hypotonic, and hypertonic all have to do with __________ solutes
nonpenetrating
What are the two states ion channels can be in?
open/closed
The unit of measure for the total concentration of solute particles (including all different molecular species) in a solution is _________(___)
osmolarity(Osm)
The pathway of a molecule that passes from the apical to the basolateral side of an epithelial membrane by going through the space between the epithelial cells, is referred to as the _________ pathway
paracellular
The type of carrier-mediated cotransport in which the energy to move a solute across a membrane against its concentration gradient is provided by the transport of sodium down its concentration gradient is called _______ ________ _______.
secondary active transport
When crossing an epithelial cell layer by the transcellular route, Na+ usually crosses the luminal membrane by ________ and it crosses the basolateral membrane using _______.
secondary active transport/Na+/K+-ATPase pumps
Mitochondria play a role in the synthesis of certain lipids, such as the hormones estrogen and testosterone. By what mechanism can these molecules leave the mitochondria and ultimately be secreted from the cell?
simple diffusion
The process of _____ _____ occurs when solute molecules move down a concentration gradient due to random molecular motion
simple diffusion
The time to diffusion equillibrium increases with the ______ of the increasing distance
square
Type of transport in which two different molecules are transported together in the same direction.
symport
The movement of molecules through an epithelial cell from the lumen of a hollow organ to the interstitial fluid is called _____________ transport
transcellular
When a substance crosses an epithelial cell layer by moving through the membranes and cytosol of the epithelial cells, the pathway is referred to as the ________ pathway
transcellular
They key difference between facillitated diffusion and simple diffusion is that facillitated diffusion uses a _________.
transporter
Ion channels that open or close in response to changes in the membrane potential are called _____-gated channels
voltage
