AP Bio-Chapter 10

Multiple Choice

One reason for carrying out the production of oxygen gas 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.

• that the concentration of water in this space is high, making it easier to form O₂ from the water.

Multiple Choice

When donating its activated electron, the chlorophyll in photosystem II is 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.

Multiple Choice

Of these events from the light reactions, which occurs first?

• Light-induced reduction of the primary electron acceptor in the reaction center of PS II.

• 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.

Multiple Choice

How many "turns" of the Calvin cycle are required to produce one molecule of glucose?

• 1

• 2

• 3

• 6

Multiple Choice

The enzyme rubisco catalyzes the fixation of carbon. Considering all the carbons involved, is the production of 3-PGA a net oxidation, reduction, or neither? 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.

Multiple Choice

If you were a cell that needed a large amount of ATP, what part of photosynthesis/the chloroplast would be most important?

• PS I

• outer membrane

• NADPH

• PEP carboxylase

Multiple Choice

Which incorrectly matches process and location?

• Oxygen gas is produced--the thylakoid space.

• Activated chlorophyll donates an electron--the thylakoid membranes.

• NADPH is oxidized to NADP⁺--the stroma.

• ATP is produced--the intermembrane space.

• Rubisco catalyzes carbon fixation--the stroma.

Multiple Choice

One way in which photosynthesis in a typical C₄ plant differs from that in a C₃ plant is that the C₄ plant

• does not produce any oxygen gas.

• 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.

Multiple Choice

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.

Multiple Choice

To make photosynthesis more efficient, which of the following should be eliminated?

• ATP synthase

• proton gradient

• photorespiration

• photophosphorylation

• none of the above

Multiple Choice

Suppose you were visiting a space station that renews the oxygen that you breathe using photosynthesis. Which would not be present in the station?

• land plants

• multicellular algae

• single-celled algae

• cyanobacteria

• purple sulfur bacteria