B. This Allows Faster Passive Transport of Small Carbohydrates

Bio102 Problems

Photosynthesis

1. Why is it advantageous for chloroplasts to have a very large (in surface area) thylakoid membrane contained within the inner membrane?

A. This limits the amount of stroma volume, keeping the concentrations of enzymes and substrates very high.

B. This allows faster passive transport of small carbohydrates.

C. This allows the organelle to have more copies of photosystems I and II and ATP synthase.

D. The larger membrane improves its fluidity.

E. This makes a more effective barrier to prevent protons from leaking through.

2. At the end of the electron transport chain found in the thylakoid membrane, the electrons are transferred to a molecule of

A. H2O.

B. NADP+.

C. O2.

D. Glucose.

E. ADP.

3. For the electron transport chain used in photosynthesis,

the initial electron donor is __water______,

the final electron acceptor is __NADP+______,

and the electron has gained/lost energy during transport.

4. Identify the metabolic process (such as fermentation, b-oxidation, etc.) that transfers energy from the molecule(s) listed in the column on the left to the molecule(s) listed in the column at right. List only one process in each empty box.

AcCoA / Citric Acid Cycle / ATP, NADH and FADH2
ATP and NADPH / Calvin-Benson Cycle
(or Light-Independent Reactions) / Glucose
Glucose / Glycolysis / NADH, ATP and Pyruvate
NADH and FADH2 / Electron Transport / Proton Gradient
Proton Gradient / Chemiosmosis / ATP
Pyruvate / Transition Step / NADH and AcCoA
Sunlight / Light-Dependent Reactions / NADPH and ATP

5. 2-carboxyarabinitol-1,5-bisphosphate (CABP) is an inhibitor of the Calvin cycle.

5A. Which one of the following enzymes might CABP inhibit?

A. Hexokinase

B. ATP synthase

C. Citrate oxidase

D. RuBisCo

E. Pyruvate decarboxylase

5B. Why does treating chloroplasts with CABP eventually also cause the light-dependent reactions of photosynthesis to cease?

NADP+ can’t be regenerated without the Calvin cycle.

6A. A drawing of a chloroplast is shown below. Draw an arrow that points to the compartment where the light-independent reactions of photosynthesis occur and write the name of this compartment below.

Stroma

6B. During the light-dependent reactions of photosynthesis, protons (H+) are actively transported across a membrane. Draw a star in the compartment that becomes more acidic and write the name of that compartment below.

Thylakoid Lumen

7. Each of the following three proteins or processes resides in a membrane and transports electrons. For each, identify the specific membrane where it is found and identify the molecule that donates the electrons to be transported.

Protein or Process / Membrane: / Electron Donor:
Complex I / Mitochondrial Inner Membrane / NADH
Complex II / Mitochondrial Inner Membrane / FADH2
Light-Dependent Reactions / Thylakoid Membrane / Water

8. Which one of the following is a reduced coenzyme that is synethsized in the Light-Dependent Reactions?

A. FADH2

B. FAD

C. NADP+

D. NADPH

E. NADH

F. NAD+

9. In a plant cell, where do the Light-Independent Reactions occur?

A. Stroma

B. Cytosol

C. Matrix

D. Intermembrane Space (IMS)

E. Thylakoid Lumen

10. Name the carbon-containing molecule(s) that result from each of the following processes. Also indicate if these carbon atoms are being oxidized, reduced or neither in these processes.

Process: / Carbon-Containing Product(s): / Redox:
Light-Independent Reactions / Glucose / ox. red. neither
Transition Step / Acetyl-CoA / ox. red. neither
b-oxidation / Acetyl-CoA / ox. red. neither
Fermentation
(in animals) / Lactate / ox. red. neither
Citric Acid Cycle / CO2 / ox. red. neither
Glycolysis / Pyruvate / ox. red. neither

11. Indicate whether each of the following statements describes electron transport on the mitochondrial inner membrane (MIM) or the light-dependent reaction of photosynthesis on the thylakoid membrane (TM) or both or neither by circling your choice.

The initial electron donor is a water molecule. / MIM / TM / both / neither
The membrane must be fluid to allow protein complexes to move. / MIM / TM / both / neither
Electrons flow from a high energy state to a low energy state. / MIM / TM / both / neither
A reduced coenzyme is produced. / MIM / TM / both / neither
Energy is stored in a proton gradient. / MIM / TM / both / neither
The electrons must pass through Complex IV. / MIM / TM / both / neither

12. For each process listed below, identify the coenzyme (or coenzymes) that are required. Then indicate if the coenzyme(s) is oxidized, reduced or neither. Similarly, identify the carbon-containing molecule that is produced by the process and indicate if those carbon atoms have been oxidized, reduced or neither during the process.

Process / Coenzyme(s) / Redox / Carbon-Containing Product(s) / Redox
Calvin Cycle / NADPH / Oxidized
Reduced
Neither / Glucose / Oxidized
Reduced
Neither
Citric Acid Cycle / NADH, FADH2 / Oxidized
Reduced
Neither / CO2 / Oxidized
Reduced
Neither
Fermentation
(in animals) / NADH / Oxidized
Reduced
Neither / Lactate / Oxidized
Reduced
Neither
Glycolysis / NADH / Oxidized
Reduced
Neither / Pyruvate / Oxidized
Reduced
Neither
Transition Step / NADH / Oxidized
Reduced
Neither / Acetyl-CoA / Oxidized
Reduced
Neither

13. Metabolic pathways represent a mechanism to transform energy from one source to another. For each of the following processes, identify the high-energy molecule (or molecules) present both before and after the process.

High-Energy Molecule(s) BEFORE the Process / Process / High-Energy Molecule(s) AFTER the Process
Acetyl-CoA / Citric Acid Cycle / NADH, FADH2
light / Electron transport from Photosystem II to Photosystem I / electron
Glucose / Anaerobic Metabolism
(in humans) / ATP, Lactate
Proton Gradient / ATP Synthase / ATP
NADPH, ATP / Light-Independent Reactions / Glucose

14. Which one of the following is a key enzyme in photosynthesis?

A. AMPK

B. RuBisCo

C. PFK

D. Hexokinase

E. Citrate Synthase

15. For each statement below, indicate if it is true for electron transport that happens in mitochondria, electron transport that happens in chloroplasts, both or neither by circling your choice.

The electron transport chain is located on the Inner Membrane. / Mitochondria / Chloroplasts / Both / Neither
Water is reduced to form molecular oxygen. / Mitochondria / Chloroplasts / Both / Neither
A coenzyme is oxidized. / Mitochondria / Chloroplasts / Both / Neither
Protons are moved by active transport. / Mitochondria / Chloroplasts / Both / Neither
Electron transport relies on a functional antenna complex / Mitochondria / Chloroplasts / Both / Neither
Energy is stored by making one compartment of an organelle more acidic. / Mitochondria / Chloroplasts / Both / Neither

16. Follow the Carbon! For each process listed below, list what carbon containing compound(s) are put in and what carbon containing compound(s) come out. Also indicate the relative numbers for each process except b-oxidation. The first one is done as an example.

Input / Process / Output
Glucose / Glycolysis / 2 Pyruvate
AcCoA / Citric Acid Cycle / CO2
Pyruvate / Fermentation
(in fungi or plants) / Ethanol + CO2
CO2 / Light-Independent Reactions / Glucose
Pyruvate / Transition Step / AcCoA + CO2
Fatty acids / b-Oxidation

17. Name one process or pathway that stores energy in each of the following molecules. Notice that there may be more than one correct answer for each blank; just choose any one that is correct.

______Citric Acid Cycle______/ stores energy in FADH2
______Glycolysis______/ stores energy in ATP
______Electron Transport____ / stores energy in a H+ gradient
______Transition Step ______/ stores energy in AcCoA
__ Light-Dependent Reactions____ / stores energy in NADPH
____ Light-Independent Reactions _ / stores energy in Glucose
______Citric Acid Cycle ______/ stores energy in NADH
______Citric Acid Cycle ______/ stores energy in GTP

18. List the high-energy molecules that are produced by each of the following processes. There may be more than one correct answer; list all that apply. It is not necessary to list the number of each molecule formed.

·  Citric Acid Cycle: NADH, FADH2, ATP

·  Glycolysis: ATP, NADH, Pyruvate

·  Transition Step: NADH, AcCoA

·  b-oxidation: AcCoA, NADH

·  Light-dependent reactions: NADPH, ATP

19. Classify each of the following reactions as an oxidation reaction, a reduction reaction, both or neither.

NADP+ → NADPH / Oxidation / Reduction / Both / Neither
ADP + PO4 → ATP / Oxidation / Reduction / Both / Neither
/ Oxidation / Reduction / Both / Neither
Pyruvate → Ethanol + CO2 / Oxidation / Reduction / Both / Neither
4 H+ + O2 → 2 H2O / Oxidation / Reduction / Both / Neither

20. For each carbon-contain molecule listed on the left, indicate which pathway (or pathways) in which it is produced. List all that apply.

A / Alcoholic Fermentation
B / b-Oxidation
__B I______/ Acetyl-CoA (AcCoA) / C / Citric Acid Cycle
__A C I____ / CO2 / D / Deamination
__A______/ Ethanol / E / Glycolysis
__G______/ Glucose / F / Light-Dependent Reactions
__E______/ Pyruvate / G / Light-Independent Reactions
H / Receptor-Mediated Endocytosis
I / Transition Step

21. It’s obvious that the Light-Independent Reactions of photosynthesis can’t continue without the high-energy molecules produced by the Light-Dependent Reactions. But would it be possible for the Light-Dependent Reactions to continue if the Light-Independent Reactions were blocked? Why or why not?

No. If the light-dependent reactions were blocked, NADPH can’t be recycled to NADP+. Without NADP+, the electrons have no where to go in the light-dependent reactions thus causing them to shut down.

22. Which complex (or complexes) is correctly described by each of the statements below?

List all that apply.

A / ATP Synthase
B / Complex I
__E______/ Releases low energy electrons to O2. / C / Complex II
__B D E F__ / Can transport protons against their diffusion gradient. / D / Complex III
__A F G H__ / Located in the thylakoid membrane. / E / Complex IV
__G H_____ / Contains chlorophyll. / F / Cytochrome Complex
___C______/ Oxidizes FADH2. / G / Photosystem I
H / Photosystem II
I / None of these

23. Both mitochondria and chloroplasts have electron transport chains. For each electron transport chain, identify the molecule (or molecules) that is the source of the electrons and where those electrons end up as they leave the chain. Also identify where the energy is stored.

Electrons are donated by / Electrons are received by / Energy is stored as
Mitochondria / NADH and FADH2 / Complex I or Complex II / Proton Gradient
Chloroplasts / Water / Photosystem II / Proton Gradient and NADPH

24. Follow the Carbon! For each process listed below, list what carbon containing compound(s) are put in and what carbon containing compound(s) come out. Also indicate the relative numbers for each process. The first one is done as an example.

Input / Process / Output
Glucose / Glycolysis / 2 Pyruvate
Acetyl-CoA / Citric Acid Cycle / CO2
Pyruvate / Alcoholic Fermentation / Ethanol and CO2
CO2 / Light-Independent Reactions / Glucose
Pyruvate / Transition Step / Acetyl-CoA and CO2