Bil 255, Cell Biology - Fall Semester - Second Examination - 2006

Bil 255, Cell Biology - Fall Semester - Second Examination - 2006 - Form 1

1. Which of the following is most correct concerning "resonance stabilization"?

1) The more stable form has fewer available positions for resonant double bonds than the less stable form.

2) Resonance stabilization provides about half of the "high energy" released when UTP releases a phosphate and forms UDP.

3) The more stable form of a molecule has less entropy than the less stable form.

4) Resonance stabilization is usually responsible for negative cooperativity found in some Michaelis-Menten enzymes.

Correct Answer is: 2

2. Which of the following enzymes has the smaller Michaelis constant?

1) glucokinase.

2) hexokinase.

Correct Answer is: 2

3. While doing some research on a newly discovered marine invertebrate, you find that its cells are only permeable to one type of ion. But you do not know what ion it is. You determine that the concentration of this ion inside the cells is 10 mM and the concentration outside the cells is 0.1 mM. The membrane potential is -62 mV at 37 degrees C. Which of the following is most likely the ion in question?

1) Iron (+3)

2) Potassium (+1)

3) Calcium (+2)

4) Phosphate (-2)

5) Chloride (-1)

Correct Answer is: 3

4. Glycophorin A has _______ transmembrane alpha-helices.

1) 0

2) 1

3) 2

4) 4

5) 6

Correct Answer is: 2

5. On resting nerve cell membranes, what is the ratio of potassium conductance to sodium conductance (gK/gNa)?

1) 0.01

2) 1.0

3) 100.

Correct Answer is: 3

6. Which of the following is a molecule that fluoresces red when excited with ultraviolet or blue light and which is used to label membrane proteins ?

1) Fluorescein.

2) Alexa Fluor 488

3) Spectrin

4) Rhodamine

Correct Answer is: 4

7. Approximately, what is the duration of an action potential?

1) 2 microseconds.

2) 2 milliseconds

3) 0.2 seconds

4) 2 seconds

Correct Answer is: 2

8. True or False: A phosphorylase is an enzyme that adds phosphate groups.

1) True.

2) False.

Correct Answer is: 1

9. Which of the following most accurately describes the allosteric inhibitors of 6-phosphofructokinase?

1) CTP is an inhibitor but ATP is not.

2) Long chain fatty acids are inhibitors but ADP and AMP are not.

3) ATP, ADP, and AMP are all inhibitors.

4) ATP, ADP, and citrate are all inhibitors.

5) ADP and AMP are inhibitors but ATP is not.

Correct Answer is: 2

10. Which of the following is a allosteric enzyme which shows negative cooperativity?

1) Lysozyme.

2) The enzyme that catalyzes the conversion of Glyceraldehyde 3-phosphate to 1,3-biphosphoglycerate.

3) The enzyme that catalyzes the conversion of Glucose to Glucose-6-phosphate.

4) Ribonuclease.

5) Hexokinase.

Correct Answer is: 2

11. Which of the following is closest to the value of the sodium Nernst potential (inside the cell) at 37 degrees centigrade, for squid giant axon cells?

1) zero

2) -62 milliVolts

3) +62 milliVolts

4) -62 microVolts

5) +62 microVolts

Correct Answer is: 3

12. Typically, what is the Sodium concentration in human blood plasma?

1) 10 micromolar.

2) 120 micromolar.

3) 10 millimolar.

4) 120 millimolar.

Correct Answer is: 4

13. With which of the following answers is "lecithin" most closely associated?

1) It is a glycolipid.

2) It indicates ABO blood groups.

3) Keratin and Lecithin are both proteins.

4) In the vertebrate liver, lecithin is the storage form of glucose.

5) It has long hydrocarbon tails attached to a glycerol backbone.

Correct Answer is: 5

14. You land on a distant planet and find that cells on that plant have only one ion - Calcium, which is permeable across cell membranes. Calcium concentrations are: [Ca+2]inside = 0.1 mM and [Ca+2]outside = 10 mM. What is the potential across the membrane (inside) at 37 degrees C?

1) +31 mV

2) -62 mV

3) +62 mV

4) -93 mV

5) -124 mV.

Correct Answer is: 3

15. You are studying membrane transport of a newly discovered small molecule. You find that this molecule always moves from a region of lower concentration to a region of higher concentration. You find that as you increase the concentration difference between the inside and outside of the cell, the rate of movement of the molecule across the membrane increases. However, as the concentration difference increases to large values, the rate of movement across the membrane appears to reach a limiting maximum value. What is the most likely mechanism for the membrane transport?

1) facilitated diffusion.

2) active transport

3) Fick's law thermal diffusion.

4) AirTran Airlines

Correct Answer is: 2

16. True or False: Cholesterol is a membrane lipid that increases membrane fluidity by filling in spaces between phospholipid molecules.

1) True.

2) False.

Correct Answer is: 2

17. True or False: Cholesterol is a phospholipid.

1) True.

2) False.

Correct Answer is: 2

18. Which is most accurate concerning membrane phospholipids of plant cells as compared with membrane phospholipids of animal cells?

1) Plant cell membrane phospholipids have more unsaturated hydrophobic chains, each of which has 6 to 10 carbons.

2) Plant cell membrane phospholipids have more unsaturated hydrophobic chains, each of which has 16 to 20 carbons.

3) Plant cell membrane phospholipids have more saturated hydrophobic chains, each of which has 6 to 10 carbons.

4) Plant cell membrane phospholipids have more saturated hydrophobic chains, each of which has 16 to 20 carbons.

Correct Answer is: 2

19. Which of the following reactions releases the most free energy? (For simplicity, only the most important components of the reaction are shown.)

1) UTP -> UDP

2) FADH2 -> FAD

3) NADH -> NAD+

Correct Answer is: 3

20. True or False: In humans, fructose is transported into the cells of the intestinal epithelium by cotransport with sodium

1) True

2) False

Correct Answer is: 2

21. When Frye and Edidin did their classical experiments on membrane fluidity, they had several technical problems. One of these was that antibodies bound to membrane proteins bound to two cells at the same time, clumping the cells together. How did they keep the cells from clumping?

1) The treated the antibodies with an enzyme which broke the antigen-binding head off the tails of the molecule.

2) They reduced cell surface proteins with mercaptoethanol.

3) They removed sodium from the external solution, thus changing the membrane potential and thus keeping the antibodies and cells from sticking together.

4) They used SDS to prevent binding of the antibody to the cells.

Correct Answer is: 1

22. You are studying membrane transport of a newly discovered small molecule. You find that this molecule always moves from regions of higher concentration to regions of lower concentration, regardless of whether the region of highest concentration is the cytoplasm or the external environment of the cell. You find that as you increase the concentration difference between the inside and outside of the cell, the rate of movement of the molecule across the membrane increases. However, as the concentration difference increases to large values, the rate of movement across the membrane appears to reach a limiting maximum value. What is the most likely mechanism for the membrane transport?

1) facilitated diffusion.

2) active transport

3) Fick's law thermal diffusion.

4) AirTran Airlines

Correct Answer is: 1

23. Which of the following best describes the action of the Na+/K+ pump?

1) For each ATP used, 3 sodium ions are pumped out from the cell and 2 potassium ions are pumped into the cell.

2) For each ATP used, 1 sodium ion is pumped out from the cell and 1 potassium ion is pumped into the cell.

3) For each ATP used, 2 sodium ions are pumped into the cell and 3 potassium ions are pumped out from the cell.

4) For each ATP used, 3 sodium ions are pumped into the cell and 2 potassium ions are pumped out from the cell.

5) For each ATP used, 2 sodium ions are pumped out from the cell and 3 potassium ions are pumped into the cell.

Correct Answer is: 1

24. If you have galactose added to ALL of the type O glycolipids that indicate the type of blood within the ABO blood groups, what type blood do you have?

1) May be either type A or type B.

2) Must be type A.

3) May be either type AB.

4) Must be type O.

5) Must be type B.

Correct Answer is: 5

25. What is the intermediate when during gluconeogenesis, Pyruvate is converted to form Phosphoenolpyruvate?

1) Lactate.

2) Oxaloacetate.

3) Acetaldehyde.

4) Malate.

5) Glutamate.

Correct Answer is: 2

26. Which of the following is a protein that is found on the inside surface of red blood cell membranes and serves the function of linking together membrane proteins and restricting their lateral mobility?

1) Band III protein.

2) Spectrin

3) Myelin

4) MHC II receptor protein

Correct Answer is: 2

27. True or False: In humans, fructose 6-phosphate -> fructose 1,6-biphosphate is catalyzed by an aldolase that covalently binds to the substrate via a sulfhydryl group.

1) True

2) False

Correct Answer is: 2

28. Which of the following best describes the distribution of cephalin between the exoplasmic and cytosolic sides of cell membranes ?

1) Most cephalin is on the cytosolic side of cell membranes

2) Most cephalin is on the exoplasmic side of cell membranes

3) Cephalin is distributed equally on both sides of cell membranes.

Correct Answer is: 1

29. Which of the following best describes the distribution of phosphatidyl inositol between the exoplasmic and cytosolic sides of cell membranes ?

1) Most phosphatidyl inositol is on the cytosolic side of cell membranes

2) Most phosphatidyl inositol is on the exoplasmic side of cell membranes

3) Phosphatidyl inositol is distributed equally on both sides of cell membranes.

Correct Answer is: 1

30. Which of the following shuttles is most important in bring reducing power into the mitochondria of nerve cells in the brain?

1) glycerol-phosphate.

2) galactose-inosine

3) kennedy-laguardia.

4) pyruvate-lactate.

5) malate-aspartate.

Correct Answer is: 1

31. Which of the following best describes the distribution of lecithin between the exoplasmic and cytosolic sides of cell membranes ?

1) Most lecithin is on the cytosolic side of cell membranes

2) Most lecithin is on the exoplasmic side of cell membranes

3) Lecithin is distributed equally on both sides of cell membranes.

Correct Answer is: 2

32. Suppose that you measure a resting membrane potential of -66 mV in a human nerve cell at 40 degrees C. If you now cool the patient down to 20 degrees C, what membrane potential will you measure in the same nerve cell?

1) -33.00 mV

2) -61.78 mV

3) -70.51 mV

4) Membrane potential will stay at -66 mV

Correct Answer is: 2

33. Animal cells use sodium pumps to remove sodium from the inside of cells. This process takes energy supplied by ATP. What ion do plant cells substitute for sodium in this process of active transport from the inside to outside of the cell?

1) hydrogen ions

2) potassium ions.

3) magnesium ions.

4) Plants pump sodium, just like animals.

Correct Answer is: 1

34. As changes in membrane potential take place after the peak of an action potential, what happens to the ratio (gK/gNa)

1) increases.

2) stays the same.

3) decreases

Correct Answer is: 1

35. As changes in membrane potential take place between the start and the peak of an action potential, what happens to the ratio (gK/gNa)

1) increases.

2) stays the same.

3) decreases

Correct Answer is: 3

36. Which of the following represents the most correct description of a difference between phospholipids in Archea and Eukarya?

1) Phosphatidyl inosine represents over 50% of Archean phospholipids whereas no Phosphatidyl inosine is found in Eukarya.

2) Archean phospholipid "tails" are linked to the rest of the molecule with thioester bonds whereas phospholipid tails of Eukarya are linked by ether bonds.

3) Archean phospholipids have isoprene "tails" whereas phospholipids of Eukarya have fatty acid "tails".

4) Archeans have lipoyl hydrophobic tails whereas Eukarya have unsaturated polymethionine tails.

Correct Answer is: 3

37. As changes in membrane potential take place between the start and the peak of an action potential, what happens to the ratio (gCl/gK)

1) increases.

2) stays the same.

3) decreases

Correct Answer is: 3

38. Which of the following neurotransmitters is most likely to have its normal function affected by interaction with LSD?

1) Glutamate

2) Glycine

3) Dopamine

4) Serotonin

5) Histamine

Correct Answer is: 4

39. Which of the following provides the energy to add glucose-1-phosphate units to a growing glycogen chain?

1) UTP

2) FAD+

3) GTP

4) CTP

Correct Answer is: 1

40. Where might we find the molecule N-Acetygalactosamine?

1) in the pyruvate dehydrogenase complex

2) one of the components of the malate-aspartate shuttle.

3) in lactic acid fermentation.

4) in red blood cell membranes

Correct Answer is: 4

This is a test file generated by tomgen

<h3> <center>Bil 255, Cell Biology - Fall Semester - Second Examination - 2006</center></h3>

1. Which of the following is most correct concerning "resonance stabilization"?

1) The more stable form has fewer available positions for resonant double bonds than the less stable form.

2) Resonance stabilization provides about half of the "high energy" released when UTP releases a phosphate and forms UDP.

3) The more stable form of a molecule has less entropy than the less stable form.

4) Resonance stabilization is usually responsible for negative cooperativity found in some Michaelis-Menten enzymes.

Correct Answer is: 2

2. Which of the following enzymes has the smaller Michaelis constant?

1) glucokinase.

2) hexokinase.

Correct Answer is: 2

1) Iron (+3)

2) Potassium (+1)

3) Calcium (+2)

4) Phosphate (-2)

5) Chloride (-1)

Correct Answer is: 3

4. Glycophorin A has _______ transmembrane alpha-helices.

1) 0

2) 1

3) 2

4) 4

5) 6

Correct Answer is: 2

5. On resting nerve cell membranes, what is the ratio of potassium conductance to sodium conductance (gK/gNa)?

1) 0.01

2) 1.0

3) 100.

Correct Answer is: 3

6. Which of the following is a molecule that fluoresces red when excited with ultraviolet or blue light and which is used to label membrane proteins ?

1) Fluorescein.

2) Alexa Fluor 488

3) Spectrin

4) Rhodamine

Correct Answer is: 4

7. Approximately, what is the duration of an action potential?

1) 2 microseconds.

2) 2 milliseconds

3) 0.2 seconds

4) 2 seconds

Correct Answer is: 2

8. True or False: A phosphorylase is an enzyme that adds phosphate groups.

1) True.

2) False.

Correct Answer is: 1

9. Which of the following most accurately describes the allosteric inhibitors of 6-phosphofructokinase?

1) CTP is an inhibitor but ATP is not.

2) Long chain fatty acids are inhibitors but ADP and AMP are not.

3) ATP, ADP, and AMP are all inhibitors.

4) ATP, ADP, and citrate are all inhibitors.

5) ADP and AMP are inhibitors but ATP is not.

Correct Answer is: 2

10. Which of the following is a allosteric enzyme which shows negative cooperativity?

1) Lysozyme.

2) The enzyme that catalyzes the conversion of Glyceraldehyde 3-phosphate to 1,3-biphosphoglycerate.

3) The enzyme that catalyzes the conversion of Glucose to Glucose-6-phosphate.

4) Ribonuclease.

5) Hexokinase.

Correct Answer is: 2

11. Which of the following is closest to the value of the sodium Nernst potential (inside the cell) at 37 degrees centigrade, for squid giant axon cells?

1) zero

2) -62 milliVolts

3) +62 milliVolts

4) -62 microVolts

5) +62 microVolts

Correct Answer is: 3

12. Typically, what is the Sodium concentration in human blood plasma?

1) 10 micromolar.

2) 120 micromolar.

3) 10 millimolar.

4) 120 millimolar.

Correct Answer is: 4

13. With which of the following answers is "lecithin" most closely associated?

1) It is a glycolipid.

2) It indicates ABO blood groups.

3) Keratin and Lecithin are both proteins.

4) In the vertebrate liver, lecithin is the storage form of glucose.

5) It has long hydrocarbon tails attached to a glycerol backbone.

Correct Answer is: 5

1) +31 mV

2) -62 mV

3) +62 mV

4) -93 mV

5) -124 mV.

Correct Answer is: 3

1) facilitated diffusion.

2) active transport

3) Fick's law thermal diffusion.

4) AirTran Airlines

Correct Answer is: 2

16. True or False: Cholesterol is a membrane lipid that increases membrane fluidity by filling in spaces between phospholipid molecules.

1) True.

2) False.

Correct Answer is: 2

17. True or False: Cholesterol is a phospholipid.

1) True.

2) False.

Correct Answer is: 2

18. Which is most accurate concerning membrane phospholipids of plant cells as compared with membrane phospholipids of animal cells?

1) Plant cell membrane phospholipids have more unsaturated hydrophobic chains, each of which has 6 to 10 carbons.

2) Plant cell membrane phospholipids have more unsaturated hydrophobic chains, each of which has 16 to 20 carbons.

3) Plant cell membrane phospholipids have more saturated hydrophobic chains, each of which has 6 to 10 carbons.

4) Plant cell membrane phospholipids have more saturated hydrophobic chains, each of which has 16 to 20 carbons.

Correct Answer is: 2

19. Which of the following reactions releases the most free energy? (For simplicity, only the most important components of the reaction are shown.)

1) UTP -> UDP

2) FADH2 -> FAD

3) NADH -> NAD+

Correct Answer is: 3

20. True or False: In humans, fructose is transported into the cells of the intestinal epithelium by cotransport with sodium

1) True

2) False

Correct Answer is: 2

1) The treated the antibodies with an enzyme which broke the antigen-binding head off the tails of the molecule.

2) They reduced cell surface proteins with mercaptoethanol.

3) They removed sodium from the external solution, thus changing the membrane potential and thus keeping the antibodies and cells from sticking together.

4) They used SDS to prevent binding of the antibody to the cells.

Correct Answer is: 1

1) facilitated diffusion.

2) active transport

3) Fick's law thermal diffusion.

4) AirTran Airlines

Correct Answer is: 1

23. Which of the following best describes the action of the Na+/K+ pump?

1) For each ATP used, 3 sodium ions are pumped out from the cell and 2 potassium ions are pumped into the cell.

2) For each ATP used, 1 sodium ion is pumped out from the cell and 1 potassium ion is pumped into the cell.

3) For each ATP used, 2 sodium ions are pumped into the cell and 3 potassium ions are pumped out from the cell.

4) For each ATP used, 3 sodium ions are pumped into the cell and 2 potassium ions are pumped out from the cell.

5) For each ATP used, 2 sodium ions are pumped out from the cell and 3 potassium ions are pumped into the cell.

Correct Answer is: 1

24. If you have galactose added to ALL of the type O glycolipids that indicate the type of blood within the ABO blood groups, what type blood do you have?

1) May be either type A or type B.

2) Must be type A.

3) May be either type AB.

4) Must be type O.

5) Must be type B.

Correct Answer is: 5

25. What is the intermediate when during gluconeogenesis, Pyruvate is converted to form Phosphoenolpyruvate?

1) Lactate.

2) Oxaloacetate.

3) Acetaldehyde.

4) Malate.

5) Glutamate.

Correct Answer is: 2

1) Band III protein.

2) Spectrin

3) Myelin

4) MHC II receptor protein

Correct Answer is: 2

27. True or False: In humans, fructose 6-phosphate -> fructose 1,6-biphosphate is catalyzed by an aldolase that covalently binds to the substrate via a sulfhydryl group.

1) True

2) False

Correct Answer is: 2

28. Which of the following best describes the distribution of cephalin between the exoplasmic and cytosolic sides of cell membranes ?

1) Most cephalin is on the cytosolic side of cell membranes

2) Most cephalin is on the exoplasmic side of cell membranes

3) Cephalin is distributed equally on both sides of cell membranes.

Correct Answer is: 1

29. Which of the following best describes the distribution of phosphatidyl inositol between the exoplasmic and cytosolic sides of cell membranes ?

1) Most phosphatidyl inositol is on the cytosolic side of cell membranes

2) Most phosphatidyl inositol is on the exoplasmic side of cell membranes

3) Phosphatidyl inositol is distributed equally on both sides of cell membranes.

Correct Answer is: 1

30. Which of the following shuttles is most important in bring reducing power into the mitochondria of nerve cells in the brain?

1) glycerol-phosphate.

2) galactose-inosine

3) kennedy-laguardia.

4) pyruvate-lactate.

5) malate-aspartate.

Correct Answer is: 1

31. Which of the following best describes the distribution of lecithin between the exoplasmic and cytosolic sides of cell membranes ?

1) Most lecithin is on the cytosolic side of cell membranes

2) Most lecithin is on the exoplasmic side of cell membranes

3) Lecithin is distributed equally on both sides of cell membranes.

Correct Answer is: 2

1) -33.00 mV

2) -61.78 mV

3) -70.51 mV

4) Membrane potential will stay at -66 mV

Correct Answer is: 2

1) hydrogen ions

2) potassium ions.

3) magnesium ions.

4) Plants pump sodium, just like animals.

Correct Answer is: 1

34. As changes in membrane potential take place after the peak of an action potential, what happens to the ratio (gK/gNa)

1) increases.

2) stays the same.

3) decreases

Correct Answer is: 1

35. As changes in membrane potential take place between the start and the peak of an action potential, what happens to the ratio (gK/gNa)

1) increases.

2) stays the same.

3) decreases

Correct Answer is: 3

36. Which of the following represents the most correct description of a difference between phospholipids in Archea and Eukarya?

1) Phosphatidyl inosine represents over 50% of Archean phospholipids whereas no Phosphatidyl inosine is found in Eukarya.

2) Archean phospholipid "tails" are linked to the rest of the molecule with thioester bonds whereas phospholipid tails of Eukarya are linked by ether bonds.

3) Archean phospholipids have isoprene "tails" whereas phospholipids of Eukarya have fatty acid "tails".

4) Archeans have lipoyl hydrophobic tails whereas Eukarya have unsaturated polymethionine tails.

Correct Answer is: 3

37. As changes in membrane potential take place between the start and the peak of an action potential, what happens to the ratio (gCl/gK)

1) increases.

2) stays the same.

3) decreases

Correct Answer is: 3

38. Which of the following neurotransmitters is most likely to have its normal function affected by interaction with LSD?

1) Glutamate

2) Glycine

3) Dopamine

4) Serotonin

5) Histamine

Correct Answer is: 4

39. Which of the following provides the energy to add glucose-1-phosphate units to a growing glycogen chain?

1) UTP

2) FAD+

3) GTP

4) CTP

Correct Answer is: 1

40. Where might we find the molecule N-Acetygalactosamine?

1) in the pyruvate dehydrogenase complex

2) one of the components of the malate-aspartate shuttle.

3) in lactic acid fermentation.

4) in red blood cell membranes

Correct Answer is: 4