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62 Cards in this Set
- Front
- Back
The ________(BLANK) molecules of membranes act as barriers to the passage of many materials
and serve to maintain the membrane's physical integrity. |
lipid
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In a complex solution, the ________(BLANK) of each substance is independent of that of the other
substances. |
diffusion |
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Lipids and proteins can move ________(BLANK) but not across biological membranes.
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laterally |
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Some materials move through biological membranes more readily than others. This characteristic of biological membranes is called selective ________. |
permeability |
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You place a cell into a solution, and the cell shrinks. This solution is ________ (BLANK)relative to the cell. |
hypertonic |
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The cells of the intestinal epithelium are joined to one another by ________(BLANK) that prevent substances from passing between the cells of this tissue. |
tight junctions |
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The coupled transport system by which glucose and sodium ions enter intestinal epithelial cells is called ________. |
symport |
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Mammalian embryos have protein complexes that couple cells together, allowing
communication by small molecules between cells. These complexes of proteins are called ________. |
gap junctions |
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Diffusion occurs ________ (BLANK)a concentration gradient.
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down |
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Three things that influence the diffusion rate are the ________(BLANK), ________(BLANK), and the ________. |
size, temperament and concentration gradient |
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Membrane synthesized on the ER moves to other points of the cell as ________.
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vesicles
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The process of one cell engulfing another is called ________. |
phagocytosis |
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The chemical makeup, physical organization, and function of a biological membrane depend on which of the following classes of biochemical compounds?
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proteins, lipids and carbohydrates
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Integral membrane proteins have
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hydrophobic regions within the lipid portion of the bilayer.
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Specialized cell junctions include
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gap junctions, tight junctions and desmosomes.
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Substances move through biological membranes against concentration gradients via
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active transport
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Because the sodium-potassium pump imports K+ ions while exporting Na+ ions, it is a
coupled transport system termed a(n) |
antiport
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When placed in water, wilted plants lose their limpness because of
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osmosis of water into the plant cells
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Houseplants adapted to indoor temperatures might die when accidentally left outdoors in
the cold because their |
membranes lack adequate fluidity
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The interior of the phospholipid bilayer is
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hydrophobic
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In biological membranes, the phospholipids are arranged in a
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bilayer with the fatty acids pointing toward each other
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A protein that forms an ion channel through a membrane is most likely to be
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an integral protein
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When a mouse cell and a human cell are fused, the membrane proteins of the two cells become uniformly distributed over the surface of the hybrid cell. This occurs because
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many proteins can move around within the bilayer.
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The hydrophilic regions of a membrane protein are most likely to be found
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exposed on the surface of the membrane.
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Biological membranes are composed of
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lipids, proteins, and carbohydrates.
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Structures that contain networks of keratin fibers and hold adjacent cells together are
called |
desmosomes
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You fill a shallow pan with water and place a drop of red ink in one end of the pan and a drop of green ink in the other end. Which of the following is true at equilibrium?
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The red and green inks are both uniformly distributed throughout the pan
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Which of the following does not affect the rate of diffusion of a substance?
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Presence of other substances in the solution
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For cells where carbon dioxide crosses the plasma membrane by simple diffusion, what
determines the rate at which carbon dioxide enters the cell? |
The concentration of carbon dioxide on each side of the membrane
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Plant cells transport sucrose across the vacuole membrane against its concentration
gradient by a process known as |
active transport
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When placed in a hypertonic solution, plant cells
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shrink
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You place cells in a solution of glucose and measure the rate at which glucose enters the cells. As you increase the concentration of the glucose solution, the rate at which glucose enters the cells increases. However, when the glucose concentration of the solution is increased above 10 M, the rate at which glucose enters the cells no longer increases. Which of the following is the most likely mechanism for glucose transport into the cell?
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Facilitated diffusion via a carrier protein
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Transporting substances across a membrane from an area of lower concentration to an
area of higher concentration requires |
energy
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In the parietal cells of the stomach, the uptake of chloride ions is coupled to the transport
of bicarbonate ions out of the cell. This type of transport system is called |
an antiport.
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When a red blood cell is placed in an isotonic solution, which of the following will
occur? |
Nothing
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When a plant cell is placed in a hypotonic solution, what occurs?
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The cell takes up water until the osmotic potential equals the pressure potential of the
cell wall. |
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Insulin is a protein secreted by cells of the pancreas. What is the pathway for the
synthesis and secretion of insulin? |
Rough ER, Golgi apparatus, vesicle, plasma membrane
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Carbohydrates associated with cellular membranes are expected to be found associated
with |
proteins outside the cell
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The site where transmembrane proteins are embedded into membranes is the
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rough E.R
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The site where carbohydrates are initially added to membrane proteins is the
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E.R.
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An important function of certain integral proteins of a eukaryotic cell's plasma membrane
is |
binding with signals in the cell's environment
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Cholesterol molecules act to
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alter the fluidity of the membrane
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The rate of facilitated diffusion of a molecule across a membrane does not continue to increase as the concentration difference of the molecule across the membrane increases.
Why? |
The transport protein must be of the carrier type
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Active transport is important because it can move molecules
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from their low concentration to a higher concentration
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Active transport usually moves molecules
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in the opposite direction as does diffusion
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Osmosis is a specific form of
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diffusion
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Osmosis moves water from a region of
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low concentration of dissolved material to a region of high concentration.
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Clathrin-coated pits are structures associated with
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receptor-mediated endocytosis
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Which of the following molecules is probably the most likely to diffuse across a cell
membrane? |
A steroid
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Membrane molecules that help individual cells organize themselves into tissues are
known as |
cell adhesion molecules
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For each molecule of ATP consumed during active transport of sodium and potassium,
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2 potassium ions are imported and 3 sodium ions are exported.
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Materials can be limited from moving through the spaces between cells by
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tight junctions between the cells.
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Keratin is a protein found in
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desmosomes
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A concentration gradient of glucose across a membrane means
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glucose molecules are more crowded on one side of the membrane than the other.
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Connexons occur in
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gap junctions
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Transport proteins that simultaneously move two molecules across a membrane in the
same direction are called |
symports
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The only process that could possibly bring glucose molecules into cells that does not
involve the meta-bolic energy of ATP is |
diffusion
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The functional roles for different proteins found in membranes include all except which
of the following? |
Stabilizing the lipid bilayer
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The tensile strength of connections between adjacent cells in tissues comes from
|
desosomers
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Desmosomes include or associate with all except A) dense plaque-like regions. B) keratin fibers. C) external cell adhesion molecules. D) internal channel proteins. E) All of the above |
E) All of the above
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Secondary active transport involves all the following except A) the direct use of ATP. B) coupling to another transport system. C) use of regained energy from an existing gradient. D) the requirement for energy. |
A) the direct use of ATP
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How do amino acids get into cells against concentration gradients?
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Secondary active transport
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