Mastering Biology: Cell Membrane Review
Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
CO2
According to the fluid mosaic model of cell membranes, phospholipids___________.
Can move laterally along the plane of the membrane.
Frye and Edidin labeled the membrane proteins of a mouse cell and a human cell with two different markers and fused the cells. In the accompanying diagram, these different markers are indicated with different colors. Based upon the results shown in the diagram, which of the following scientific questions below provided conclusive evidence through its investigation?
Do some membrane proteins move sideways within the phospholipid bilayer?
Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water__________.
Is hypotonic and the salt solution is hypertonic to the cells of the celery stalks.
Which of the following is a characteristic feature of a carrier protein in a plasma membrane?
It exhibits a specificity for a particular type of molecule
Which of the following membrane activities required energy from ATP?
Movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid.
Which of the following most accurately describes selective permeability?
Only certain molecules can cross a cell membrane
Three lab groups carried out an experiment to identify the correct molarities for five solutions. Each unknown contained one of the following sucrose concentrations: From the data given, which statement most accurately describes what is occurring in response to a particular unknown solution?
Osmosis of water molecules from unknown solution A likely caused the increase in mass observed.
You have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. After testing the permeability of this membrane to glucose, you increase the proportion of unsaturated phospholipids in the bilayer. What will happen to the membrane's permeability to glucose?
Permeability to glucose will increase
The difference between pinocytosis and receptor mediated endocytosis is that_______.
Pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
Suppose the cell shown in this figure is secreting insulin, a protein hormone, via exocytosis. Which statement most accurately describes why this mechanism of transport is ideal for insulin secretion?
Proteins are large molecules that cannot be transported efficiently across the membrane via transport proteins.
You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells?
Similarity of the drug molecule to other molecules transported by the target cells
A patient was involved in a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water equal to the volume of blood lost is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?
Th patient's red blood cells will swell and possibly burst because the blood has become more hypotonic compared the the cells.
What will happen to a red blood cell (RBC), which had an internal ion concentration of about 0.9 percent, if it is placed into a beaker of pure water?
The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.
What would be observed by live-cell fluorescence immediately after HIV entry if HIV is endocytosed first, and then later fuses with the endocytotic vesicle membrane?
The red fluorescent dye- labeled lipids will appear in the infected cell's interior.
Which of the following would increase the electrochemical gradient across a membrane?
a proton pump
In which of the following would there be the greatest need for osmoregulation?
a salmon moving from a river into an ocean
For a protein to be an integral membrane protein, it would have to be_________.
amphipathic, with at lease one hydrophobic region
Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells? the animal cell is in________.
an isotonic solution, and the plant cell is in a hypotonic solution
Which of the following allows water to move much faster across cell membranes?
aquaporins
Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. At higher temperatures, these regions__________.
are less fluid than the surrounding membrane
In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane? They are synthesized________.
by ribosomes in the rough ER and arrive at the plasma membrane in the membrane of the secretory vesicles.
The sodium-potassium pump is called an electrogenic pump because it_________.
contributes to the membrane potential
Which of the following is true of osmosis?
in osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
The membranes of winter wheat are able to remain fluid when it is extremely cold by_________.
increasing the percentage of unsaturated phospholipids in the membrane
A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in_______.
lysosomes
The voltage across a membrane is called the_________.
membrane potential
A sodium-potassium pump_________.
moves three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle.
In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?
on the inside surface of the vesicle
White blood cells engulf bacteria using________.
phagocytosis
What kinds of molecules pass through a cell membrane most easily?
small and hydrophobic
When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur?
the cell will become turgid.
The solutions in the two arms of this U-tube are separated by a membrane that is permeable to water and glucose but not to sucrose. Refer to the figure. After the system reaches equilibrium, what changes are observed?
the water level is higher in side A than in side B
Ions diffuse across membranes through specific ion channels down_______.
their electrochemical gradients