Which of the following sequences correctly represents the flow of electrons during photosynthesis?

A. H2O > NADPH > Calvin Cycle

B. NADPH > Chlorophyll > Calvin Cycle

C. NADPH > Electron transport chain > O2

D. NADPH > O2 > CO2

E. H20 > Photosystem 1 > Photosystem 2

A. H2O > NADPH > Calvin cycle

Photosynthesis is a redox reaction. This means that H₂O is _____ during the light reactions and CO₂ is _____ during the Calvin cycle.

A. Oxidized ... Reduced

B. Reduced ... Reduced

C. Consumed ... Consumed

D. Consumed ... Reduced

E. Reduced ... Oxidized

A. Oxidized ... Reduced

What is the basic role of CO₂ in photosynthesis?

A. CO₂ is fixed or incorporated into organic molecules.

B. CO₂ is taken in by plants as a form of inverse respiration, in which carbon dioxide is “breathed in” and oxygen is “breathed out.”

C. CO₂ is a source of electrons in the formation of organic molecules.

A. CO₂ is fixed or incorporated into organic molecules.

Which of the following is a product of the light reactions of photosynthesis?

A. Glyceraldehyde-3-phosphate

B. High-energy photons

C. Oxygen, ATP, and NADPH

D. NADP+ and RuBP

E. Water and CO₂

C. Oxygen, ATP, and NADPH

Photosystem 1

Photosystem 2

Photosystem 1 & 2

Reduction of NADP+

Reduction of primary electron acceptor

Oxidation of electron transport chain between two photosystems

Reduction of electron transport chain between the two photosystems

Light absorption

Oxidation of water

Photosystem 1

Oxidization of water

Reduction of electron transport chain between the two photosystems

P2

Reduction of NADP+

Oxidation of electron transport chain between two photosystems

P1&2

Reduction of primary electron acceptor

Light absorption

Electron transport step l Energy input required

1. Water > P680+
2. P680 > Pq (plastoquinone)
3. Pq > P700+
4. P700 > Fd (ferredoxin)
5. Fd > NADP+

Electron transport step l Energy input required

1. Water > P680+ … no energy
2. P680 > Pq (plastoquinone) … energy
3. Pq > P700+ … no energy
4. P700 > Fd (ferredoxin) ... energy
5. Fd > NADP+ … no energy

Diagram of H+ movement

1. P. –
2. P.Site of H+ release
3. P. Site of ATP synthesis
4. B. H+ pumped across membrane
5. B. –
6. B. H+ diffuses across membrane

When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by _____.

A. Oxidizing glucose

B. Fixing carbon

C. Splitting water

D. Breaking down ATP

E. Removing them from NADPH

C. Splitting water

C₄ plants occur more commonly in desert conditions because _____.

A. They store carbon by incorporating CO₂ into organic acids that are later catabolized

B. They produce water as a product of their photosynthetic pathways

C. The stomata open at night and close in the day

D. They can fix carbon at the lower CO₂ concentrations that develop when the stomata are closed

E. They produce carbon dioxide internally via photorespiration

D. They can fix carbon at the lower CO₂ concentrations that develop when the stomata are closed

Carbon fixation involves the addition of carbon dioxide to _____.

A. Rubisco

B. G3P

C. NADPH

D. RuBP

E. 3-PGA

D. RuBP

After 3-PGA is phosphorylated, it is reduced by _____.

A. CO₂

B. NADPH

C. ATP

D. ADP

E. NADP⁺

B. NADPH

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?

A. 6

B. 2

C. 10

D. 4

E. 8

A. 6

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?

A. 1

B. 3

C. 2

D. 4

E. 5

B. 3

Which term describes ATP production resulting from the capture of light energy by chlorophyll?

A. Substrate-level phosphorylation

B. Photophosphorylation

C. Dephosphorylation

D. Oxidative phosphorylation

B. Photophosphorylation

True or false? The chemiosmotic hypothesis states that the synthesis of ATP generates a proton gradient that leads to electron flow through an electron transport chain.

True

False

False

According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?

A. Temperature gradient

B. Osmotic gradient

C. Electrons

D. Proton gradient

D. Proton gradient

Which of the following particles can pass through the ATP synthase channel?

A. ATP

B. ADP

C. Inorganic phosphate

D. Protons

D. Protons

True or false? The region of ATP synthase that catalyzes the production of ATP from ADP and inorganic phosphate spans the chloroplast membrane.

True

False

False

Chloroplast membrane vesicles are equilibrated in a simple solution of pH 5. The solution is then adjusted to pH 8. Which of the following conclusions can be drawn from these experimental conditions?

A. ATP will be produced because the proton gradient favors proton movement through the ATP synthase channels.

B. ATP will not be produced because there is no ADP and inorganic phosphate in the solution.

C. The change in the solution's pH results in a gradient across the chloroplast membranes such that there is a lower concentration of protons inside the vesicles and a higher concentration outside.

D. Protons will not diffuse toward the outside of the vesicles.

B. ATP will not be produced because there is no ADP and inorganic phosphate in the solution.

_____ has a longer wavelength than _____.

A. Yellow ... red

B. Red ... green

C. Violet ... blue

D. Green ... yellow

E. Blue ... green

B. Red ... green

The overall function of the Calvin cycle is _____.

A. Making sugar

B. Producing carbon dioxide

C. Capturing sunlight

D. Splitting water

E. Oxidizing glucose

A. Making sugar

In mechanism, photophosphorylation is most similar to

A. Reduction of NADP⁺.

B. Carbon fixation.

C. The Calvin cycle.

D. Oxidative phosphorylation in cellular respiration.

E. Substrate-level phosphorylation in glycolysis.

D. Oxidative phosphorylation in cellular respiration.

Which of these phosphorylates ADP to make ATP?

a. A

b. D

c. E

d. C

e. B

C. E

_____ releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment.

A. E

B. C

C. B

D. D

E. A

C. B

_____ splits water into 1/2 O₂, H⁺, and e^- .

A. B

B. C

C. A

D. E

E. D

C. A

Energized electrons from ____ enter an electron transport chain and are then used to reduce NADP⁺.

A. B

B. E

C. A

D. C

E. D

D. C

Chlorophyll can be found in _____.

A. B and C

B. A and C

C. A and B

D. B and D

E. B and E

B. A and C

Which of these equations best summarizes photosynthesis?

A. C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 12 H₂O

B. H₂O → 2 H⁺ + 1/2 O₂ + 2e^-

C. 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

D. 6 CO₂ + 6 O₂ → C₆H₁₂O₆ + 6 H₂O

E. C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + Energy

C. 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂

Where does the Calvin cycle occur?

A. C

B. E

C. D

D. B

E. A

B. E

The light reactions of photosynthesis use _____ and produce _____.

A. Water ... NADPH

B. NADPH ... oxygen

C. Carbon dioxide ... oxygen

D. NADPH ... NADP⁺

E. Carbon dioxide ... sugar

A. Water ... NADPH

Select the correct molecule that is the main product of the Calvin cycle.

A. G3P

B. NADPH

C. Glucose

A. G3P

In C₃ plants the conservation of water promotes _____.

A. A shift to C₄ photosynthesis

B. The light reactions

C. The opening of stomata

D. Photosynthesis

E. Photorespiration

E. Photorespiration

In C₄ and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells.

A. Grana

B. Thylakoids

C. Cytoplasm

D. Stomata

E. Stroma

C. Cytoplasm

C₄ plants differ from C₃ and CAM plants in that C₄ plants _____.

A. Use malic acid to transfer carbon dioxide to the Calvin cycle

B. Transfer fixed carbon dioxide to cells in which the Calvin cycle occurs

C. Are better adapted to wet conditions

D. Open their stomata only at night

E. Use PEP carboxylase to fix carbon dioxide

B. Transfer fixed carbon dioxide to cells in which the Calvin cycle occurs

How is photosynthesis similar in C₄ plants and CAM plants?

A. In both cases, rubisco is not used to fix carbon initially.

B. Both types of plants make sugar without the Calvin cycle.

C. In both cases, only photosystem I is used.

D. Both types of plants make most of their sugar in the dark.

E. In both cases, thylakoids are not involved in photosynthesis.

A. In both cases, rubisco is not used to fix carbon initially.