Quiz 2 Flashcards
What is the term that describes the change to -70 mV (negative 70mV) from -50 mV (negative 50mV) membrane potential in a neuron?
Repolarization
In comparing two solutions, the one that is hypertonic _________.
would increase the concentration of a hypotonic solution if they were mixed together
Nacl (nonpenetrating) mM |Urea (penetrating) mM
Solution W 150 100
Solution X 100 150
Solution Y 200 100
Solution Z 100 50
Solution X in the table is _________ and __________ with respect to a red blood cell.
hyperosmotic; hypotonic
A patient was involved in a serious accident and lost a large quantity of blood. An inexperienced observer suggests replenishing body fluids by adding distilled water to the blood directly via one of their veins. What would be the most probable result of this transfusion?
The patient’s red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.
Red blood cells have a higher proportion of aquaporins on the membrane than skin cells do. Assuming the cells have equal osmotic pressures, which of the following statements is TRUE?
The rate of osmosis is greater in red blood cells than in skin cells.
The permeability of the plasma membrane to ions
is affected by differences in electrical changes on the two sides of the membrane.
You examine a cell by electron microscopy and find a molecule on the outside of the cell and in vesicles in the cytoplasm. The most likely explanation is that this substance moved into the cell by
Endocytosis
Which of the following is an INCORRECT statement?
Diffusion of a solute through a membrane is considerably quicker than diffusion of the same through a water layer of equal thickness.
Five dialysis bags constructed of a membrane which is permeable to water and impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were weighed and the percentage change in mass of each bag was graphed which you can see below.
If you assume that the dialysis bags behave like cells do, which line(s) in the graph represent(s) bags that contain a solution that is hypertonic at 50 minutes?
B (linear line that has positive slope)
Nacl (nonpenetrating) mM |Urea (penetrating) mM
Solution W 150 100
Solution X 100 150
Solution Y 200 100
Solution Z 100 50
Solution W in the table is _________ and __________ with respect to a red blood cell.
hyperosmotic; isotonic
Which properties are characteristic of ion channels?
They can open and close depending on the presence of any three types of gates.
Depolarization of an axon is caused by
Inward diffusion of Na+
In order for molecule X to cross the plasma membrane of a cell, it must first bind to an specific membrane protein that spans the membrane. The binding of molecule X to the membrane protein immediately causes a conformational change to the membrane protein, which exposes molecule X to the other side of the membrane with a lower concentration of molecule X where it is then released. What type of solute movement across a membrane is this an example of?
facilitated diffusion
If a small amount of urea were added to an iso-osmotic solution and cells are exposed to this solution, what would be the result?
The cells would first shrink but then be restored to normal volume after a brief period of time.
Which of the following statements regarding integral membrane proteins is FALSE?
Integral membrane proteins can be added or removed without causing a great deal of disruption to the membrane structure.
What is TRUE about the resting membrane potential?
It requires the uneven distribution of relatively few ions across the cell membrane.
What is TRUE about mediated transport across cell membranes?
It is characterized by saturable carriers and a maximum rate of transport.
What is TRUE about the Na/K ATPase pump in neurons?
It generates a small electrical potential such that the inside is more negative with respect to the outside.
In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two types of proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by ________.
cotransport
Which of the following conditions does NOT require ATP hydrolysis?
Osmosis
