Multiple Choice Questions

Some disease-causing microbes attack the body by turning on or off specific signal transduction pathways. In the disease cholera, the bacterium Vibrio cholerae causes massive diarrhea by interfering with such a pathway. A toxin from this bacterium enters intestinal cells and chemically modifies G proteins. Once modified, the G proteins can no longer cleave GTP into GDP. What would you expect to see within the intestinal cells of a person with cholera?
  • The receptor protein does not undergo self-phosphorylation.
  • The listed number of membrane proteins involved in primary active transport is not correct.
  • the movement of water across selectively permeable membranes.
  • The G proteins remain activated and continually activate adenylyl cyclase.
Adenylyl cyclase
  • results in the formation of clathrin-coated vesicles.
  • can result in several thousand events at the end of the pathway.
  • makes cAMP from ATP with the liberation of pyrophosphate (PPi).
  • specific integral membrane proteins mediate transport.
A student created the table above as a study guide. Evaluate the accuracy of the information shown.
  • the movement of water across selectively permeable membranes.
  • The G proteins remain activated and continually activate adenylyl cyclase.
  • The listed number of membrane proteins involved in primary active transport is not correct.
  • The fish's cells would slow production of cholesterol and increase production of unsaturated, short chain fatty acids.
What advantage is gained by having so many steps in one signal transduction pathway?
  • carbohydrates; glycoproteins; glycolipids
  • Simple; facilitated
  • decrease; adenylyl cyclase; decrease
  • Greater amplification of the signal
_______ diffusion and _______ diffusion are two types of passive transport.
  • Greater amplification of the signal
  • swell and lyse (burst).
  • A: endocytosis; B: exocytosis
  • Simple; facilitated
How do primary and secondary active transport mechanisms differ?
  • Across a broad temperature range, fluidity of the cell membrane decreases as temperature decreases.
  • Carrier proteins bind to the substances they transport across the membrane via facilitated diffusion, whereas channel proteins provide a pore for substances to move across the membrane via facilitated diffusion.
  • can result in several thousand events at the end of the pathway.
  • The goal of primary active transport is to move ions across the cell membrane against their concentration gradients; the goal of secondary active transport is to establish these same gradients to drive transport of another substance.
Three substances need to be maintained inside a cell at the concentrations shown in column 2 of the table above. Which substance(s) are most likely to be moved across the membrane by passive transport if the typical external concentrations are those shown in column 3?
  • The fish's cells would slow production of cholesterol and increase production of unsaturated, short chain fatty acids.
  • swell and lyse (burst).
  • X only
  • A: K+; B: O2; C: galactose
Both primary and secondary active transport require energy in the form of _______ to drive substances across a cell membrane
  • can result in several thousand events at the end of the pathway.
  • The goal of primary active transport is to move ions across the cell membrane against their concentration gradients; the goal of secondary active transport is to establish these same gradients to drive transport of another substance.
  • swell and lyse (burst).
  • ATP
Suppose the concentration of epinephrine in the bloodstream of an animal drops. The cyclic AMP concentration in liver cells would be expected to _______ because _______ activity would _______.
  • decrease; adenylyl cyclase; decrease
  • Greater amplification of the signal
  • The receptor protein does not undergo self-phosphorylation.
  • A: K+; B: O2; C: galactose
If a suspension of red blood cells in an isotonic NaCl solution was suddenly diluted with pure water by a factor of 10, the cells would
  • decrease; adenylyl cyclase; decrease
  • swell and lyse (burst).
  • carbohydrates; glycoproteins; glycolipids
  • A: K+; B: O2; C: galactose
The phosphorylation of proteins by ATP
  • is catalyzed by enzymes known as "protein kinases."
  • results in the formation of an Na+ concentration gradient across the cell membrane.
  • results in the formation of clathrin-coated vesicles.
  • specific integral membrane proteins mediate transport.
A species of fish spends part of its life cycle under conditions of moderate temperatures and part of its life cycle under extremely cold conditions. What change in the cell membranes of this fish might be expected to occur as conditions shift from moderate to extremely cold temperatures?
  • can result in several thousand events at the end of the pathway.
  • decrease; adenylyl cyclase; decrease
  • The receptor protein does not undergo self-phosphorylation.
  • The fish's cells would slow production of cholesterol and increase production of unsaturated, short chain fatty acids.
In facilitated diffusion,
  • results in the formation of clathrin-coated vesicles.
  • results in the formation of an Na+ concentration gradient across the cell membrane.
  • involves proteins in plasma membranes.
  • specific integral membrane proteins mediate transport.
The sodium-potassium pump (or Na+-K+ pump)
  • results in the formation of an Na+ concentration gradient across the cell membrane.
  • Across a broad temperature range, fluidity of the cell membrane decreases as temperature decreases.
  • results in the formation of clathrin-coated vesicles.
  • is catalyzed by enzymes known as "protein kinases."
How are temperature and fluidity of the cell membrane related?
  • results in the formation of an Na+ concentration gradient across the cell membrane.
  • The goal of primary active transport is to move ions across the cell membrane against their concentration gradients; the goal of secondary active transport is to establish these same gradients to drive transport of another substance.
  • Across a broad temperature range, fluidity of the cell membrane decreases as temperature decreases.
  • Carrier proteins bind to the substances they transport across the membrane via facilitated diffusion, whereas channel proteins provide a pore for substances to move across the membrane via facilitated diffusion.
Osmosis is
  • specific integral membrane proteins mediate transport.
  • the movement of water across selectively permeable membranes.
  • makes cAMP from ATP with the liberation of pyrophosphate (PPi).
  • The receptor protein does not undergo self-phosphorylation.
Each substance, A, B, and C, is transported across the cell membrane via passive transport. Identify the substances corresponding to their specific type of transport checked in the table.
  • decrease; adenylyl cyclase; decrease
  • X only
  • swell and lyse (burst).
  • A: K+; B: O2; C: galactose
0 h : 0 m : 1 s

Multiple Choice Questions
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