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March 2011 Membrane Dynamic and Enzymes

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 
 
The image below shows a lipid bilayer with a representation of a  particulat type of membrane transport. Labels 1 and 2 indicate the compartments and do not identify any structures.
nar001-1.jpg
 

 1. 
Based on the above image which of the following is a incorrect statement?
a.
The concentration gradient of X would predict that X would flow from compartment 1 to compartment 2.
b.
X is a polar molecule
c.
The membrane is selectively permeable.
d.
X is being actively transported against it’s concentration gradient.
e.
When only considering the concentration of X, the compartment labeled 2. is hypertonic to compartment 1
 
 
The following graph shows enzymatic activity of two different enzymes at different pH. Each reaction is measured by how much product (mL/minute) is made for each enzymatic reaction.

nar002-1.jpg
 

 2. 
Which of the following statments can be directly supported from the data collected in this graph?
a.
Both enzymes have excellent reactivity at all pH’s.
b.
Both enzymes are functional under limited pH ranges
c.
Both enzymes are highly functional at very basic pH’s.
d.
Glucose 6-phosphatase is activated by a cofactor.
e.
The optimal pH of pepsin gives a higher rate of product than glucose 6-phosphatase at it’s optimal pH.
 

 3. 
Which of the following statements is FALSE?
a.
Pepsin’s optimal pH is pH 2.
b.
Pepsin is denatured at pH 8.
c.
Both enzymes have limited function at pH 5.
d.
Glucose 6-phosphatase has an optimal pH at 8
e.
Glucose 5 phosphatase has limited function but still producing product at pH 4.
 
 
The following image shows a concentration gradient with a selectively permeable membrane. Assume the membrane is freely permeable by the solute shown in compartment 1.
nar003-1.jpg
 

 4. 
Assume the image above shows the system at time 0 minutes. If you return to the system after 20 minutes, which best describes the results you would expect to find
a.
the system reached equilibrium
b.
some of the solute moved from compartment 1 to compartment 2.
c.
equal amounts of solute is moving in either direction at any given moment.
d.
relatively equal concentrations of solute on either side of the membrane.
e.
all of the above are correct statements
 
 
The following image is a U-tube with an unknown solute dissolved into water divided by a selectively permeable membrane. Assume that the membrane impermeable to the solute but freely permeable to water.
nar004-1.jpg
 

 5. 
Assume this sytem is shown at time 0 minutes. Whixh of the following statements would best describe what happens to the system after 20 minutes?
a.
The solute would move until there is equal concentrations of solute on both side of the membrane
b.
The water will move from side 2 to side 1.
c.
The water will move from side 1 to side 2
d.
The solute will diffuse from side 2 to side 1.
e.
Both the water and the solute will move from side 1 to side 2.
 
 
The following image shows a cell doing bulk transport.
nar005-1.jpg
 

 6. 
The above image is showe a type membrane transport. Which of the following best describes this type of transport?
a.
Active transport
b.
Passive transport
c.
facilitated diffusion
d.
pinocyctosis
e.
phagocytosis
 
 
The following question uses the information from the table below to create one of the graphs below.

nar006-1.jpg
 

 7. 
Given the above data set for Enzyme Rate and Substrate Concentration, which graph best describes the trend from the data?
a.
A
d.
D
b.
B
e.
E
c.
C
 
 
The data set below was collected and then graphed.
nar007-1.jpg
 

 8. 
Which of the above graphs correctly match the data collected?
a.
A
b.
B
c.
C
d.
D
e.
E
 
 
Answer the following questions based on the diagram below:
nar008-1.jpg
 

 9. 
This diagram shows a:
a.
Dehydration synthesis reaction.
b.
hydrolysis reaction.
c.
Formation of a peptide bond.
d.
Both (a) and (c) above.
e.
None of the above.
 

 10. 
What molecule should be identified in place of (3)?
a.
Inhibitor.
b.
Enzyme.
c.
Water.
d.
Inhibitors.
e.
None of the above.
 

 11. 
Which statement(s) are true?
a.
Enzymes facilitate reactions by lowering activation energy.
b.
This single enzyme is able to catalyze many different reactions by binding various substrates.
c.
Once an enzyme catalyzes a reaction, it is disabled or “used up”.
d.
Enzymes are lipids.
e.
Enzymes only catalyzes reactions that break down molecules.
 

 12. 
What binds to the region labeled (2)?
a.
Substrate.
b.
Competitive inhibitor.
c.
Noncompetitive inhibitor.
d.
Both (a) and (b).
e.
All of the above.
 

 13. 
The region where the substrate binds this enzyme is called the:
a.
active site.
b.
promoter.
c.
operon.
d.
plasmid.
e.
inner thylakoid space.
 
 
The diagram below shows a transmembrane protein (a protein embedded in the lipid bilayer) that acts as a channel to transport molecules across the membrane. You should recognize the parts of the lipid bilayer by comparing them to an earlier question which shows the membrane in the same view.

The boxed area highlights details of the protein chain that sits in the membrane.  Each “R” represents a separate sidechain and is labeled 1 through 5.  Answer the following questions based on your understanding of the structure and characteristics of amino acids, proteins, and the lipid bilayer.
nar009-1.jpg
 

 14. 
This channel protein, the potassium channel, facilitates the movement of potassium ions across the cell membrane by what would be referred to as “facilitated diffusion”.  Which of the following would be true about the functions of this protein?
a.
The protein is capable of moving all dissolved solutes across the membrane.
b.
The channel requires ATP as energy to function.
c.
The net movement of the potassium through the protein continues in one direction as long as ATP is available.
d.
The net movement of the potassium through the protein would stop when its concentration reaches equilibrium across the membrane.
e.
Both (a) and (b) above.
 
 
Answer the following questions based on the diagram below.  1, 2, and 3 represent the process.  4 and 5 represents the highlighted structure.
nar010-1.jpg
 

 15. 
Which part(s) of the diagram represents facilitated diffusion?
a.
1
b.
2
c.
3
d.
Both 1 and 2
e.
All 1, 2, and 3
 

 16. 
Which part(s) of the diagram represents a type of passive transport?
a.
1
b.
2
c.
3
d.
Both 1 and 2
e.
All 1, 2, 3
 

 17. 
Which part of the diagram represents a type of transport that is able to establish an area of higher solute concentration by moving molecules against a concentration gradient?
a.
1
b.
2
c.
3
d.
All 1, 2, and 3
e.
None of the above
 

 18. 
The structures labeled (4) and (5)
a.
are types of proteins.
b.
are channel proteins.
c.
contain hydrophobic amino acids that help the remain stabilized in the lipid bilayer.
d.
are made up of amino acids.
e.
All of the above.
 

 19. 
The function of ATP synthase is dependent on the movement of hydrogen ions moving down a concentration gradient.  Which of the illustrations best describes the movement of hydrogen ions through ATP synthase.
a.
1.
b.
2.
c.
3.
d.
1 and 2.
e.
All of the above.
 

 20. 
Oxygen is a small, non polar molecule. Which of the following best shows its passage through the cell membrane
a.
1
b.
2
c.
3
d.
1 and 2- when at the inner mitochondrial membrane
e.
1 and 4- 4 only when under anaerobic conditions
 
 
Answer the following questions based on the diagram below and your understanding of the mechanisms of diffusion and osmosis.  It will help to recall the observations made during the diffusion lab.

A beaker is set up with the following initial conditions.  The bag in the beaker is made up of dialysis tubing. 
nar011-1.jpg
 

 21. 
Starch is not able to pass through this membrane; IKI, glucose, sucrose, and water can.  Which of the following will be false?
a.
After 60 minutes, only the water in the beaker will be stained a dark black.
b.
After 60 minutes, only the water in the bag will be stained black.
c.
After 60 minutes, the IKI will diffuse into the bag.
d.
After 60 minutes, both the water in the beaker and the bag will test positive with Benedicts.
e.
The water initially placed in the beaker will test positive for Benedicts.
 

 22. 
Imagine the same experimental setup as the earlier question.  In this experiment, both starch and sucrose are not able to pass through the membrane.  IKI, glucose, and water can still pass through.

Which of the following will be true about the appearance and characteristics of the system after 60 minutes?
a.
The water in the beaker will show a positive IKI test.
b.
The water inside the bag will test negative with Benedicts.
c.
There will be a net movement of water into the bag.
d.
There will be a net movement of water out of the bag.
e.
There will be no net movement of water between the bag and the beaker.
 
 

Answer the following questions using the diagram below.  Each question may require you to make different assumptions for the conditions represented in the diagram.  Read the question carefully before selecting an answer.
nar012-1.jpg
 

 23. 
The dialysis bag is filled with 20% sucrose solution.  Which beaker contains a solution that is hypotonic to the solution inside the dialysis bag?
a.
Beaker 1
b.
Beaker 2
c.
Beaker 3
d.
Both beaker 2 and 3
e.
Not enough information to determine
 

 24. 
Again, the bag is filled with 20% sucrose solution.  Which statement is false about the dialysis bag used in the above experiment?
a.
The dialysis bag is selectively permeable.
b.
The dialysis bag is permeable to water.
c.
The dialysis bag is permeable to sucrose.
d.
Both (b) and (c) are false.
e.
All statements are false.
 

 25. 
The dialysis bag is filled with a 20% glucose solution.  Glucose is able to pass through the dialysis membrane.  Which of the three beakers would resemble the appearance of the bag after being placed in pure water for 30 minutes?
a.
Beaker 1
b.
Beaker 2
c.
Beaker 3
d.
None of the above
e.
Not enough information to determine
 

 26. 
The process seen here is the movement of water across a selectively permeable membrane because of a difference in solute concentration.  This is called:
a.
Osmosis.
b.
Active transport.
c.
Endocytosis.
d.
Bulk transport.
e.
Mass transit.
 
 
The following graph is based on potato cores soaked in various concentrations of sucrose for twenty for house.
nar013-1.jpg
 

 27. 
Using the graph above, the average mass of the potato core soaked in pure water tends to
a.
gain mass
d.
lose water
b.
lose mass
e.
both a and c
c.
gain water
f.
both b and d
 

 28. 
The potato cores in .25 M concentration of sucrose are said to be in  ----.
a.
isotonic solution since they lose mass
b.
hypotonic solution since they gain mass
c.
hypertonic solution since they lose mass
d.
saline solution since the cores gain mass
e.
both b and d are correct
 

 29. 
Which of the following statement(s)  is/are correct?
a.
The area marked A is referring to a hypertonic solution
b.
The area marked B is referring to an isotonic solution
c.
The area marked C is referred to as a weak solution
d.
The area marked D is referred to as a hypertonic solution
e.
Both B and D are corrent
 
 
The following shows a lipid bilayer with an embedded protein. The red circles are solutes are in the aqueous environment. Labels 2 and 3 referring to the compartments: ICF or ECF

nar014-1.jpg
 

 30. 
Based on the above diagram, it can be assumed that the solute particles are ---- and ---.
a.
nonpolar.....must move through a transport protein
b.
polar.....must move through a transport protein
c.
hypertonic....and must move through a transport protein
d.
hypotonic.....and will move down it’s concentration gradient
e.
polar.....can move through the lipid bilayer
 

 31. 
Which of the following statements regarding the above diagram is (are) false?
a.
The solute particles are moving down their concentration gradient?
b.
The solute particles are moving via the process of facilitated diffusion
c.
The solute particles are polar
d.
The diagram is showing active transport of solute particles
e.
The diagram is passive transport
 

 32. 
Which of the following statements is true about the above diagram.
a.
Area 3 is hypertonic to area 2
b.
Area 3 is hyportonic to area 2
c.
Area 2 is hypotonic to area 3
d.
Area 2 is hypertonic to area 3
e.
both a and c are true
 
 
The following image is a a picture of an onion cell. The cells have a unique stain that stains the entire cytoplasm of the cell.

nar015-1.jpg
 

 33. 
Observing the above diagram, which of the following statements is false?
a.
The observed cells are in a hypertonic environment.
b.
The observed cells are in a hypotonic environment.
c.
The observed cells are losing water to the environment
d.
The observed cells are eukaryotic.
e.
The observed cells are shrinking in volume.
 

 34. 
In which of the following is solution X hypotonic relative to solution Y?
a.
Solution X has a greater solute concentration than Y.
b.
Solution X has a lower solute concentration than solution Y.
c.
Solution X and solution Y have the same solute concentration.
d.
all of the above
e.
none of the above
 

 35. 
A marathon runner has just arrived in the emergency room with severe dehydration, and you, the physician, must decide which type of solution to pump into his veins: pure water, 0.9 % saline, 1.5 % saline.  (Hint: Blood cells are approximately 0.9 saline)
Which solution should you use to correctly treat the patient?
a.
Since the runner is critically dehydrated, you should use pure water. This puts the cells in a hypotonic environment and water will rush into the cell rehydrating the cells.
b.
You should use the 1.5 saline since this will force the cells to uptake water from the surrounding environment.
c.
You should use the .0.9 saline since this isotonic to body tissues.
d.
You should use the .9 saline since this will be hypertonic to a severely dehydrated runner.
e.
You should use the pure water since this will place the cells in a hypertonic environment and rehydrate the cells.
 



 
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