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Exam 2 Practice Questions
Cell Biology
Fall 2000 Lantz
Note: answers will not be posted. You should be able to answer all of these questions by
studying your notes and/or text. Please see me if you have trouble with a question(s).
Multiple choice. Circle the letter next to the best answer.
1. If you isolate mitochondria and place them in buffer with a low pH they begin to
manufacture ATP. Why?
A. Low pH increases the OH- concentration in the matrix resulting in ATP production by
ATP synthase.
B. Low pH increases the acid concentration in the mitochondrial matrix, a condition that
normally causes ATP production by ATP synthase.
C. The high external acid concentration causes an increase in H+ in the inner membrane
space leading to increased ATP production by ATP synthase.
D. Low pH increases the concentration of base causing mitochondria to pump out H+ to the
inner membrane space leading to ATP production by ATP synthase.
2. Most of the energy harvested by the citric acid cycle is conserved as:
A.
B.
C.
D.
E.
NADH
FAD
GTP
carbon dioxide
acetyl Coenzyme A
3. Within photosystem II, in what order do the following events occur?
w. chlorophyll molecules located within the antenna complex absorb a photon of light
x. excited chlorophyll molecules funnel their energy to the reaction center
y. a chlorophyll molecule loses a high-energy electron
z. electrons are transferred to plastoquinone
A.
B.
C.
D.
E.
w, x, y, z
w, y, z, x
w, z, y, x
w, x, z, y
w, y, x, z
4. In cellular respiration, CO2 is released:
A.
B.
C.
D.
during glycolysis.
during the citric acid cycle.
during oxidative phosphorylation.
as electrons are transferred through the respiratory enzyme complexes.
5. Decreasing the length of the hydrocarbon tails in cell membrane phospholipids would:
A.
B.
C.
D.
increase the fluidity of the membrane.
decrease the fluidity of the membrane.
increase the rate of passive transport.
decrease the rate of passive transport.
6. Which of the following statements regarding chromosomes is false?
A. Each eucaryotic chromosome consists of a single, long linear DNA molecule plus
associated proteins
B. Mitotic chromosomes are more compact than interphase chromosomes.
C. Negatively charged histone proteins located in nucleosomes are among the
most highly conserved of all known proteins.
D. The sum of the DNA in the chromosomes of an organism is called its genome.
7. What would be the consequences if eucaryotic chromosomes lacked centromeres?
A.
B.
C.
D.
The chromosomes would not attach to the mitotic spindle.
The DNA would not be transcribed.
The DNA would not become condensed.
DNA replication could not be initiated efficiently.
8. The direction of transfer of uncharged solutes across a biological membrane is determined by
the:
A.
B.
C.
D.
membrane potential
electrochemical gradient
voltage across the membrane
concentration gradient
9. An antiport is:
A. an ion channel that can simultaneously transport two ions of like charge across a
membrane in the opposite direction
B. a carrier protein that transports a single solute molecule symmetrically in either
direction across a membrane, depending on the direction of the electrochemical gradient
of the solute.
C. a simple ion channel which can transport either positive or negative ions.
D. a carrier protein that couples the transport of two solute molecules in the opposite
direction across a membrane.
10. At the end of glycolysis, there is a net gain of ___________ for each glucose molecule
broken down.
A. one molecule of pyruvate, one molecule of ATP, and one molecule of NADH
B. one molecule of glyceraldehyde 3-phosphate, one molecule of pyruvate, and four
molecules of ATP.
C. two molecules of pyruvate, four molecules of ATP, and two molecules of NADH
D. two molecules of pyruvate, two molecules of ATP, and two molecules of NADH
11. For a voltage-gated ion channel, the probability of being in an open configuration is
controlled by the:
A.
B.
C.
D.
E.
membrane potential
fluidity of the membrane
specific binding of an extracellular ligand to the gate
rate of ATP hydrolysis
none of the above
12. In the citric acid cycle, acetyl CoA reacts with a four-carbon molecule,
____________________, to form a six-carbon molecule.
A.
B.
C.
D.
succinate
citrate
isocitrate
oxaloacetate
13. Ion channels:
A.
B.
C.
D.
are single pass transmembrane proteins.
transfer solutes more slowly than carrier proteins.
discriminate between ions according to their charge and size.
can actively transport ions across membranes.
14. Which of the following statements about mitochondria is false?
A.
B.
C.
D.
protons are pumped from the inner membrane space into the matrix.
The inner membrane is folded into cristae.
The outer membrane is permeable to protons.
The respiratory enzymes complexes are located in its inner membrane.
15. __________________ acts as the final electron acceptor in the mitochondrial electron
transport chain.
A.
B.
C.
D.
CO2
O2
Cytochrome oxidase complex
H2O
16. What is the primary advantage that cells capable of using oxygen in cellular respiration have
over cell that can only conduct fermentation?
17. What is the role of flippases in lipid bilayer (membrane) synthesis?
18. Draw a diagram illustrating how a plant cell uses a H+ gradient to couple the active transport
of sucrose across the membrane into the cell. Be sure to include and label all components that
are required to establish the H+ gradient and transport sucrose.
19. The symbols A, C, G, and T are commonly used to donate the four different nucleotides that
are used to construct a DNA molecule. What are the complete (unabbreviated) names of
these nucleotides? (careful)
20. Draw a schematic diagram of ATP synthase as it is found in the inner mitochondrial
membrane. Label all of the individual proteins that make up ATP synthase and the location
of the matrix and inner membrane space. Describe the unique way in which the
electrochemical proton gradient (i.e. the proton motive force) is used by ATP synthase to
generate ATP synthesis. Finally, indicate on your diagram the location of the newly
generated ATP.
For questions 21-26, fill in the blanks
21. In plant and animal cells, ________________________________ is the site where the most
of the cells ATP is generated.
22. _____________________________________ is widely claimed to be the most
abundant protein on earth.
23. For every three molecules of CO2 that enter the carbon fixation cycle, one new
molecule of ____________________________________ is produced. This can be converted
into ____________________________________ in the stroma where it serves as a
carbohydrate reserve
24. The sole site of H+-pumping in the chloroplast electron-transport chain is
_____________________________________.
25. The spontaneous movement of a substance down its concentration or electrochemical
gradient with the help of a channel or carrier protein is called
_____________________________________.
26. All of the carbohydrate on the glycoproteins and glycolipids is located on the noncytosolic
side of the plasma membrane where it forms a sugar coating called the
_____________________________________.