1. Photosythesis

2. Which of the following is a correct explanation for how carbons in a triose-phosphate can be said to be in a more reduced state than carbons in carbon dioxide? (See image on next slide.)
Carbons in triose-phosphates have accepted more electrons, and have taken on a full negative charge, relative to carbons in carbon dioxide.
Carbons in triose-phosphate have more bonds with hydrogen and fewer bonds with oxygen relative to carbons in carbon dioxide.
Converting carbon in carbon dioxide into carbon in triose- phosphate is an endergonic process.
Carbons in carbon dioxide donate their excess electrons to NADP as they are converted to carbons in triose-phosphate.
The binding with a phosphate by the triose-phosphate makes it higher in energy relative to carbons in carbon dioxide.
Answer: B

4. Which of the following is a correct explanation for how carbons in a triose-phosphate can be said to be in a more reduced state than carbons in carbon dioxide is?
Carbons in triose-phosphates have accepted more electrons, and have taken on a full negative charge, relative to carbons in carbon dioxide.
Carbons in triose-phosphate have more bonds with hydrogen and fewer bonds with oxygen relative to carbons in carbon dioxide.
Converting carbon in carbon dioxide into carbon in triose- phosphate is an endergonic process.
Carbons in carbon dioxide donate their excess electrons to NADP as they are converted to carbons in triose-phosphate.
The binding with a phosphate by the triose-phosphate makes it higher in energy relative to carbons in carbon dioxide.

5. Which of the following INCORRECTLY matches a process with its typical location?
Oxygen gas is produced—the soluble space surrounded by the thylakoid membranes
Activated chlorophyll donates an electron—in the thylakoid membranes
NADPH is oxidized to NADP—the stroma of the chloroplast
ATP is produced—the space between the two chloroplast envelope membranes
RUBISCO catalyzes carbon fixation—the stroma of the chloroplast
Answer: D

6. Which of the following INCORRECTLY matches a process with its typical location?
Oxygen gas is produced—the soluble space surrounded by the thylakoid membranes
Activated chlorophyll donates an electron— in the thylakoid membranes
NADPH is oxidized to NADP—the stroma of the chloroplast
ATP is produced—the space between the two chloroplast envelope membranes
RUBISCO catalyzes carbon fixation—the stroma of the chloroplast

7. Of the following events from the light reactions of photosynthesis, which would be expected to occur first?
Light-induced reduction of the primary electron acceptor in the reaction center of PS II takes place.
While being split, electrons are taken out of water.
donation of electrons from reduced Pq to the cytochrome complex
acceptance of electrons by Pc from the cytochrome complex
Pq gets electrons from the reduced primary electron acceptor of PS II.
Answer: A
(Image modified from figure )

8. Of the following events from the light reactions of photosynthesis, which would be expected to occur first?
Light-induced reduction of the primary electron acceptor in the reaction center of PS II takes place.
While being split, electrons are taken out of water.
donation of electrons from reduced Pq to the cytochrome complex
acceptance of electrons by Pc from the cytochrome complex
Pq gets electrons from the reduced primary electron acceptor of PS II.

9. When donating its activated electron, the chlorophyll in photosystem II (P680) is said to be a very powerful oxidizing agent. This is best shown by its ability to
make use of a proton electrochemical gradient to drive the formation of ATP.
force the oxidation of oxygen in water to oxygen gas.
donate an electron to plastoquinone (Pq).
absorb light energy to power redox reactions.
force the reduction of NADP+ to NADPH.
Answer: B

10. When donating its activated electron, the chlorophyll in photosystem II (P680) is said to be a very powerful oxidizing agent. This is best shown by its ability to
make use of a proton electrochemical gradient to drive the formation of ATP.
force the oxidation of oxygen in water to oxygen gas.
donate an electron to plastoquinone (Pq).
absorb light energy to power redox reactions.
force the reduction of NADP to NADPH.

11. One good reason for carrying out the production of oxygen gas (O2) in the space surrounded by the thylakoid membranes, and not in the stroma of the chloroplasts, is
that this makes it easier for O2 to exit the chloroplast.
that the hydrogen ions released can contribute to the H electrochemical gradient being generated.
to reduce the concentration of O2 in the stroma so that organic matter located there is not oxidized by it.
that the concentration of water in this space is high, making it easier to form O2 from the water.
that carrying out this process in the stroma would tend to dry out this compartment and denature the enzymes of the Calvin cycle located there.
Answer: B

12. One good reason for carrying out the production of oxygen gas (O2) in the space surrounded by the thylakoid membranes, and not in the stroma of the chloroplasts, is:
that this makes it easier for O2 to exit the chloroplast.
that the hydrogen ions released can contribute to the H electrochemical gradient being generated.
to reduce the concentration of O2 in the stroma so that organic matter located there is not oxidized by it.
the concentration of water in this space is high, making it easier to form O2 from the water.
carrying out this process in the stroma would tend to dry out this compartment and denature the enzymes of the Calvin cycle located there.

13. Which makes an INCORRECT comparison between the membrane and surrounding compartments indicated in mitochondria and chloroplasts by the boxes (see figure)?
The darker compartment will often be more positively charged and more acidic.
The flow of electrons between items in the membrane results in protons being pumped from the darker to the lighter compartments.
The lighter compartment is where much of the carbon metabolism is done.
This membrane has an ATP synthase in it.
The lighter compartments are both similar to the cytosolic compartment of bacteria.
Answer: B
(Image modified from fig ; keep the shading as it is.)

14. Which makes an INCORRECT comparison between the membrane and surrounding compartments indicated in mitochondria and chloroplasts by the boxes (see figure)?
The darker compartment will often be more positively charged and more acidic.
The flow of electrons between items in the membrane results in protons being pumped from the darker to the lighter compartments.
The lighter compartment is where much of the carbon metabolism is done.
This membrane has an ATP synthase in it.
The lighter compartments are both similar to the cytosolic compartment of bacteria.

15. Both alter the redox state of carbons.
The net reactions for some aerobic respiratory processes in mitochondria, and for some reactions of photosynthesis in the chloroplast are given below. Pyruvate import and the Citric acid cycle: Pyruvic acid + FAD + 4NAD+ + ADP + Pi ÷ 3CO2 + FADH2 + 4NADH + 4H++ ATP The Calvin cycle: 3CO2 + 9ATP + 5H2O + 6NADPH  Glyceraldehyde 3-phosphate + 9ADP + 8Pi + 6NADP+ + 3H+ The following are descriptions of proposed similarities between these two sets of reactions. Which is FALSE?
Both alter the redox state of carbons.
Both take place in a soluble space that is homologous to a bacterial cytoplasmic space.
Both involve a three carbon organic acid, either as a substrate or as a product.
Both couple very exergonic reactions to drive forward endergonic reactions of smaller net magnitude.
Both involve various types of nucleic acids in the exchange of hydrogens.
Answer: C

16. The net reactions for some aerobic respiratory processes in mitochondria, and for some reactions of photosynthesis in the chloroplast are given below. Pyruvate import and the Citric acid cycle: Pyruvic acid + FAD + 4NAD+ + ADP + Pi ÷ 3CO2 + FADH2 + 4NADH + 4H++ ATP The Calvin cycle: 3CO2 + 9ATP + 5H2O + 6NADPH  Glyceraldehyde 3-phosphate + 9ADP + 8Pi + 6NADP+ + 3H+ The following are descriptions of proposed similarities between these two sets of reactions. Which is FALSE?
Both alter the redox state of carbons.
Both take place in a soluble space that is homologous to a bacterial cytoplasmic space.
Both involve a three carbon organic acid, either as a substrate or as a product.
Both couple very exergonic reactions to drive forward endergonic reactions of smaller net magnitude.
Both involve various types of nucleic acids in the exchange of hydrogens.

17. The enzyme rubisco catalyzes the fixation of carbon (see reaction on next slide). Considering all the carbons involved, is the production of 3-PGA a net oxidation, reduction, or neither, and why?
Oxidation. Adding a carbon dioxide makes the products more oxidized.
Reduction. Adding the hydrogens from the water results in a more reduced condition.
Reduction. The carbon in the carbon dioxide has been slightly reduced.
Neither. There is no change in the total C–O and C–H bonds between the products and reactants.
Oxidation. The RuBP acts as oxidizing agent in this reaction.
Answer: D

19. The enzyme rubisco catalyzes the fixation of carbon (see reaction on next slide). Considering all the carbons involved, is the production of 3-PGA a net oxidation, reduction, or neither, and why?
Oxidation. Adding a carbon dioxide makes the products more oxidized.
Reduction. Adding the hydrogens from the water results in a more reduced condition.
Reduction. The carbon in the carbon dioxide has been slightly reduced.
Neither. There is no change in the total C–O and C–H bonds between the products and reactants.
Oxidation. The RuBP acts as oxidizing agent in this reaction.

20. One way in which photosynthesis as done in a typical C4 plant differs from that in a C3 plant, is that the C4 plant
does not produce any oxygen gas at all.
actively pumps oxygen gas away from the cells that contain rubisco.
avoids the use of rubisco entirely; instead, it uses PEP carboxylase to catalyze all carbon fixation.
keeps its stomata more open, so that more CO2 can enter the plant.
carries out the Calvin cycle only in the chloroplasts of bundle-sheath cells.
Answer: E

21. One way in which photosynthesis as done in a typical C4 plant differs from that in a C3 plant, is that the C4 plant
does not produce any oxygen gas at all.
actively pumps oxygen gas away from the cells that contain rubisco.
avoids the use of rubisco entirely; instead, it uses PEP carboxylase to catalyze all carbon fixation.
keeps its stomata more open, so that more CO2 can enter the plant.
carries out the Calvin cycle only in the chloroplasts of bundle-sheath cells.

22. In CAM plants, CO2 is
temporarily fixed in phloem cells and later permanently fixed in the bundle-sheath cells.
mainly obtained from oxidative respiratory processes.
temporarily fixed at night and later permanently fixed during the day.
fixed into organic matter just by the action of the enzyme rubisco.
brought up to the leaves through air spaces in the stem so that the stomata of the leaves can be kept shut to prevent water loss.
Answer: C

23. In CAM plants, CO2 is
temporarily fixed in phloem cells and later permanently fixed in the bundle-sheath cells.
mainly obtained from oxidative respiratory processes.
temporarily fixed at night and later permanently fixed during the day.
fixed into organic matter just by the action of the enzyme rubisco.
brought up to the leaves through air spaces in the stem so that the stomata of the leaves can be kept shut to prevent water loss.