Sample Exam 2 Questions – Respiration and Photosynthesis
Multiple Choice. Choose the BEST answer !!
1. Suppose that compound A accepts electrons from compound B. What has happened to
compound A?
A. It has been oxidized.
B. It has been reduced.
C. It has more energy.
D. A and C are correct.
E. B and C are correct.
2. Which of the following is not produced in any of the steps of glycolysis?
A. NAD+
B. NADH
C. ADP
D. ATP
E. Pyruvate
3. When a muscle cell metabolizes glucose in the complete absence of molecular oxygen,
all of the following substances are produced except
A. NADH
B. ATP
C. Pyruvate
D. Lactic acid
E. Acetyl-CoA
4. Which of the following does not produce carbon dioxide?
A. a plant cell in the dark
B. a yeast cell under anaerobic conditions
C. a mitochondrion under aerobic conditions
D. muscle cells under anaerobic conditions
E. a plant cell in the light
5. The enzymes that catalyze the reactions of the Krebs cycle are found in which
subcellular organelle in eukaryotes?
A. chloroplast
B. ribosome
C. lysosome
D. mitochondrion
E. endoplasmic reticulum
6. When pyruvate is converted to acetyl-CoA
A. NADH and carbon dioxide are formed.
B. NADH and ATP are formed.
C. carbon dioxide and ATP are formed.
D. NADH is formed.
E. carbon dioxide, NADH, and ATP are formed.
7. A principal product of the Krebs cycle is
A acetyl-CoA.
B. citric acid.
C. ADP
D. oxidized electron carriers.
E. reduced electron carriers.
8. How many ATP molecules are synthesized directly in the Krebs cycle if you supply
aerobically respiring cells with 10 pyruvate molecules?
A. 2
B. 5
C. 10
D. 20
E. 300
9. In cellular metabolism, O2 is used
A. to provide electrons for photophosphoryation.
B. in glycolysis.
C. in fermentation.
D. as a terminal electron acceptor.
E. in the Krebs cycle.
10. The chemiosmotic generation of ATP is driven by
A. osmotic movement of water into an area of high solute concentration.
B. The addition of protons to ADP and phosphate using enzymes.
C. A difference in hydrogen ion concentration on either side of a membrane.
D. Substrate-level phosphorylation.
E. None of the above.
11. Which of the following statements best describes the relationship between
photosynthesis and respiration?
A. Respiration is the exact reversal of the biochemical pathways of photosynthesis.
B. Photosynthesis stores energy in complex organic molecules and respiration releases it.
C. ATP molecules are produced in photosynthesis and used in respiration.
D. Photosynthesis occurs only in plants and respiration occurs only in animals.
E. Respiration requires a proton gradient and photosynthesis does not.
12. The ultimate fate of an oxygen atom that begins the photosynthetic process as part of
a water molecule is to
A. combine with a free oxygen atom to become oxygen gas.
B. reassociate with hydrogen ions to become a new molecule of water.
C. reassociate with free carbon and oxygen atoms to become carbon dioxide gas.
D. become part of the carbohydrate product made in the Calvin cycle.
E. combine with carbon dioxide to become glucose.
13. Suppose that you use a specific poison to prevent water from being split during
photosynthesis. Which of the following would continue to take place?
A. oxygen production
B. reduction of carbon dioxide
C. synthesis of ATP
D. transport of electrons from one photosystem to another
E. reduction of NADP+
14. When a chlorophyll molecule in photosystem I traps light, it loses an electron. In
noncyclic electron flow this electron is replaced
A. from one of the antenna pigments.
B. from the other end of photosystem I.
C. by a donation from photosystem II.
D. by a donation from an unexcited chlorophyll molecule.
E. from one of the hydrogen atoms in water.
15. Which of the following compounds are both products of the light-dependent reactions
in photosynthesis and also reactants in the light-independent reactions?
A. NADPH and O2
B. NADPH and ATP
C. NADP+ and CO2
D. NADP+ , ATP, and CO2
E. NADP+, ATP and O2
16. In chemiosmotic synthesis of ATP during photosynthesis, the hydrogen ions diffuse
from the
A. stroma to the thylakoid interior.
B. cytoplasm to cross the outer chloroplast membrane.
C. stroma to cross the inner chloroplast membrane.
D. thylakoid interior to the stroma.
E. space between the inner and outer membranes to enter the stroma.
17. In the light-independent reactions of photosynthesis
A. carbon dioxide is incorporated into an organic molecule.
B. oxygen is produced.
C. ATP is made.
D. A and C are correct.
E. A, B, and C are correct.
18. Carbon dioxide is reduced in
A. cyclic photophosphorylation.
B. noncyclic photophosphorylation.
C. the light reactions of photosynthesis.
D. the Calvin cycle.
E. Both the light-dependent and light-independent reactions of photosynthesis.
19. The reason why C4 plants can fix relatively more carbon than C3 plants when oxygen
concentration in the plant cell is high is that
A. the plants do not have rubisco.
B. the plants have rubisco.
C. the initial carbon dioxide fixation enzyme cannot use oxygen as a substrate.
D. carbon enters the Calvin cycle directly from the air.
E. they utilize a process called photorespiration.
1. The following reaction has a G = +7.1 kcal/mol
malic acid + NAD+ ↔ oxaloacetic acid + NADH + H+
a. Is NAD+ oxidized or reduced? Are electrons gained or lost?
b. Would this reaction occur spontaneously? Explain why.
c. Which is greater – the free energy of the products or reactants?
d. If the free energy of the reactants is 2.4 kcal/mol, what is the free energy of the
products?
e. If this reaction was occurring in a test tube and had reached equilibrium, what
are two ways that the equilibrium could be disrupted?
2. In the reaction
X+Y↔Z
T is an inhibitor that has a structure similar to Y.
a. What type of inhibitor is T?
b. If both of the follwing reactions can occur with equal probability
E + T + Y ↔ ET + Y ( ET is inactive)
E + T + Y ↔ EY + T (EY is active)
how can you force the formation of the active form?
c. If another inhibitor, B, binds to a site away from the active site, what kind of
inhibitor is B?