chapter 5(1) 5(2)
Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements.
.The diverse proteins found in and attached to membranes perform many important functions. .The framework of a membrane is a bilayer of phospholipids with their hydrophilic heads facing the aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center. .Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane.
Active and passive transport of solutes across a membrane typically differ in which of the following ways?
Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.
Which of the following statements is TRUE with regard to this animation?
Both sodium and potassium ions are transported against their concentration gradients.
In what way do the membranes of a eukaryotic cell vary?
Certain proteins are unique to each kind of membrane.
Which of the following correctly describes some aspect of exocytosis or endocytosis?
Exocytosis and endocytosis change the surface area of the plasma membrane.
When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?
The cell will become turgid.
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
Which of the following statements about osmosis is correct?
The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.
Which of the following statements about osmosis is correct?
The presence of aquaporins proteins that form water channels in the membrane should speed up the process of osmosis.
Which of the following is true of integral membrane proteins?
They are usually transmembrane proteins.
In facilitated diffusion, what is the role of the transport protein?
Transport proteins provide a hydrophilic route for the solute to cross the membrane.
Which of the following factors would tend to increase membrane fluidity?
a greater proportion of unsaturated phospholipids
A protein that spans the phospholipid bilayer one or more times is
a transmembrane protein.
In order for a protein to be an integral membrane protein it would have to be
amphipathic, with at least one hydrophobic region.
Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. At high temperatures, these regions
are less fluid than the surrounding membrane.
The sodium-potassium pump is called an electrogenic pump because it
contributes to the membrane potential.
The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following?
cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis
Which of the following is least likely to be important in holding the components of a biological membrane together?
covalent interactions between the phospholipid and protein components of the membrane
The movement of the hydrophobic gas nitrous oxide (N2O) (laughing gas) into a cell is an example of
diffusion across the lipid bilayer.
Ions diffuse across membranes through specific ion channels
down their electrochemical gradients.
The presence of cholesterol in the plasma membranes of some animals
enables the membrane to stay fluid more easily when cell temperature drops.
This is an animation of _____.
exocytosis
Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?
facilitated diffusion
This cell is in a(n) _____ solution.
hypertonic
Endocytosis moves materials _____ a cell via _____.
into ... membranous vesicles
charged
ions
What name is given to the process by which water crosses a selectively permeable membrane?
osmosis
nonpolar
oxygen, carbon dioxide,lipds
Which of the following processes includes all the others?
passive transport
Which of these are not embedded in the hydrophobic portion of the lipid bilayer?
peripheral proteins
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis
Which of the following types of molecules are the major structural components of the cell membrane?
phospholipids and proteins
polar
sucrose, water,proteins
Which of the following would be a factor that determines whether the molecule selectively enters the target cells?
the similarity of the drug molecule to other molecules that are transported into the target cells
The permeability of a biological membrane to a specific polar solute may depend on which of the following?
the types of transport proteins in the membrane
The primary function of polysaccharides attached to the glycoproteins and glycolipids of animal cell membranes is
to mediate cell-to-cell recognition.
Structure A in this animation is a(n) _____.
transport protein
Which of the following best describes the structure of a biological membrane?
two layers of phospholipids with proteins either crossing the layers or on the surface of the layers
Which of the following statements about a typical plasma membrane is correct?
two sides of the plasma membrane have different lipid and protein composition.