Cell Biology Exam 3 CH 11 PHOTOSYNTHESIS

A- STROMA B- THYLAKOID MEMBRANE C- CYTOSOL D- LOCATION OF CALVIN CYCLE E- THYLAKOID SPACE F- LOCATION OF LIGHT REACTIONS G-ENVELOPE MEMBRANES

-Identify the membranes or compartments of the chloroplast by dragging the blue labels to the blue targets. -Then, identify where the light reactions and Calvin cycle occur by dragging the pink labels to the pink targets.

H20 O2

1. In the light reactions, light energy is used to oxidize ____ to ____.

NADP+ NADPH

2. The electrons derived from this oxidation reaction in the light reactions are used to reduce ____ to ____.

NADPH NADP+

3. The Calvin cycle oxidizes the light-reactions product ____ to ____.

CO2 G3P

4. The electrons derived from this oxidation reaction in the Calvin cycle are used to reduce ___ to ___.

D- Proton Gradient A proton gradient across chloroplast and mitochondrial membranes drives ATP synthesis by the enzyme ATP synthase.

According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis? A- Electrons B- Osmotic gradient C- Temperature gradient D- Proton gradient

C -NADPH NADPH supplies the electrons that reduce the phosphorylated 3-PGA.

After 3-PGA is phosphorylated, it is reduced by _____. A- ADP B- ATP C- NADPH D- CO2 E- NADP+

B- transfer fixed carbon dioxide to cells in which the Calvin cycle occurs In C3 and CAM plants carbon dioxide fixation and the Calvin cycle occur in the same cells.

C4 plants differ from C3 and CAM plants in that C4 plants _____. A- use PEP carboxylase to fix carbon dioxide 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 malic acid to transfer carbon dioxide to the Calvin cycle

D- they can fix carbon at the lower CO2 concentrations that develop when the stomata are closed

C4 plants occur more commonly in desert conditions because __________. A- they store carbon by incorporating CO2 into organic acids, which are later catabolized B- their stomata open at night and close in the day C- they produce water as a product of their photosynthetic pathways D- they can fix carbon at the lower CO2 concentrations that develop when the stomata are closed

In the Calvin cycle, the energy outputs from the light reactions (ATP and NADPH) are used to power the conversion of CO2 into the sugar G3P. As ATP and NADPH are used, they produce ADP and NADP+, respectively, which are returned to the light reactions so that more ATP and NADPH can be formed.

Calvin Cycle Fill in the blanks

B- RuBP In the Calvin cycle, carbon dioxide is added to RuBP.

Carbon fixation involves the addition of carbon dioxide to _____. A- 3-PGA B- RuBP C- G3P D- NADPH E- Rubisco

A and C The photosystems contain chlorophyll.

Chlorophyll can be found in _____. A and B B and D A and C B and C B and E

The key function of each of the two photosystems is to absorb light and convert the energy of the absorbed light into redox energy, which drives electron transport. In PS II (the first photosystem in the sequence), P680 is oxidized (which in turn oxidizes water), and the PS II primary electron acceptor is reduced (which in turn reduces the electron transport chain between the photosystems). In PS I, the PS I primary electron acceptor is reduced (which in turn reduces other compounds that ultimately reduce NADP+ to NADPH), and P700 is oxidized (which in turn oxidizes the electron transport chain between the photosystems).

Drag each item into the appropriate bin depending on whether the process is associated with Photosystem II (PS II) only, Photosystem I (PS I) only, or both PS II and PS I.

C- Energized electrons from photosystem I are used to reduce NADP+.

Energized electrons from ____ enter an electron transport chain and are then used to reduce NADP+. D E A B C

D- All of the answers are correct

For which of the following reasons should glucose NOT be considered a primary product of photosynthesis? A- Starch is the storage form of fixed carbon. B- The first reduced sugar formed is 3-phosphoglyceraldehyde (3 carbons). C- The carbon fixation reactions fix one CO2 at a time, not six. D- All of the answers are correct.

6 Six carbon dioxide molecules are required to produce two G3P molecules, which can be combined to make one glucose molecule.

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose? 4 8 2 6 10

D

Identify a thylakoid. C B E A D

A

Identify the chloroplast. E B A D C

E

Identify the stroma. C D E B A

B- Photorespiration Conserving water simultaneously reduces the amount of carbon dioxide available to the plant.

In C3 plants the conservation of water promotes _____. A- the opening of stomata B- photorespiration C- a shift to C4 photosynthesis D- photosynthesis E- the light reactions

E- Cytoplasm In C4 and CAM plants carbon dioxide fixation occurs in the cytoplasm.

In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells. A- grana B- thylakoids C- stomata D- stroma E- cytoplasm

3

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules? 3 4 1 5 2

In the light reactions, the energy of sunlight is used to oxidize water (the electron donor) to O2 and pass these electrons to NADP+, producing NADPH. Some light energy is used to convert ADP to ATP. The NADPH and ATP produced are subsequently used to power the sugar-producing Calvin cycle.

Light Reactions Fill in the blanks

in direct proportion to the amount of O2 produced

The NADPH required for CO2 fixation is produced __________. A- by the hydrolysis of ATP B- by cyclic photophosphorylation C- in direct proportion to the amount of O2 produced D -by the reduction of O2

B- water ... NADPH

The light reactions of photosynthesis use _____ and produce _____. A- NADPH ... oxygen B- water ... NADPH C- carbon dioxide ... oxygen D- NADPH ... NADP+ E- carbon dioxide ... sugar

D- The Calvin cycle depends on ATP and NADPH, which are most readily available from the light reactions.

The reactions of the Calvin cycle are NOT directly dependent on light, but they usually do NOT occur at night. Why? A- Carbon dioxide concentrations decrease at night. B- It is often too cold at night for these reactions to take place. C- Plants usually open their stomata at night. D- The Calvin cycle depends on ATP and NADPH, which are most readily available from the light reactions.

False The chemiosmotic hypothesis states that the flow of electrons through an electron transport chain generates a proton gradient that leads to the synthesis of ATP.

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- The water molecules are split to replenish electrons in photosystem II, leaving behind protons, which are used to generate a proton gradient for the formation of ATP, and oxygen, which is released as a by-product.

True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.

False The region of ATP synthase that catalyzes ATP production protrudes out of, but does not span, the chloroplast membrane; the region that spans the membrane is an ion channel through which protons can pass.

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

B- They convert carbon dioxide to sugar. All organisms use the sugars produced by photosynthesis to generate energy.

What is the biological significance of the light-independent reactions of photosynthesis? A- They make oxygen. B- They convert carbon dioxide to sugar. C- They generate ATP and NADPH. D- They convert ATP to sugar.

D- The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere? A- The light-independent reactions use CO2 to make ATP. B- The light-independent reactions turn glucose, a sugar, into CO2 gas. C- The light-independent reactions turn sugar into ATP for energy. D -The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.

The Calvin cycle occurs in the stroma. E - Stroma

Where does the Calvin cycle occur? E D B C A

D- cytochrome b6f and ATP synthase

Which enzymes of the light reactions are most likely to be inhibited by inhibitors of mitochondrial oxidative phosphorylation? A- photosystem I and ferrodoxin B- photosystem II and rubisco C- photosystem II and photosystem I D- cytochrome b6f and ATP synthase

A- photosystem II, cytochrome complex, photosystem I

Which is the correct order of flow of electrons through the thylakoid membrane during energy transduction reactions? A- photosystem II, cytochrome complex, photosystem I B- photosystem II, photosystem I, cytochrome complex C- cytochrome complex, photosystem I, photosystem II D- cytochrome complex, photosystem II, photosystem I

D- ferredoxin-NADP+ reductase

Which of the following enzymes represents the link between the light and dark reactions of photosynthesis? A- photosystem I B- rubisco C- photosystem II D- ferredoxin-NADP+ reductase

A- Antenna pigments allow more wavelengths of light and more photons to be captured, increasing the efficiency of light capture.

Which of the following explains why photosystem units contain a high proportion of antenna pigments compared to reaction centers? A- Antenna pigments allow more wavelengths of light and more photons to be captured, increasing the efficiency of light capture. B- Antenna pigments contain rubisco. C- Antenna pigments split water. D- Antenna pigments help reduce the reaction centers.

D- NADPH The NADPH produced by photosystem I is used to supply energy for the production of sugars during photosynthesis.

Which of the following molecules is the primary product of photosystem I? A- Oxygen B- Carbon dioxide C- ATP D- NADPH

B- Protons The channels formed by ATP synthase are specific for protons.

Which of the following particles can pass through the ATP synthase channel? A- ATP B- Protons C- ADP D- Inorganic phosphate

B- Regneration of RuBP The regeneration of RuBP ensures that the Calvin cycle can proceed indefinitely, since RuBP fixes carbon dioxide into an organic molecule that is used to produce sugar.

Which of the following reactions ensures that the Calvin cycle can make a continuous supply of glucose? A- Production of 3-phosphoglycerate B- Regneration of RuBP C -Carbon fixation D- Production of G3P

A- The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions. Light energy drives the formation of ATP and NADPH during the light-dependent reactions; these energy molecules are then used during the light-independent reactions to form sugars.

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis? A- The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions. B- The light-dependent reactions produce carbon dioxide, which is then used by the light-independent reactions. C- The light-dependent reactions pass electrons through an electron transport chain to the light-independent reactions. D -The light-independent reactions release energy, and the light-dependent reactions require energy.

A- 6 CO2 + 6 H2O → C6H12O6 + 6 O2

Which of these equations best summarizes photosynthesis? A- 6 CO2 + 6 O2 → C6H12O6 + 6 H2O B- H2O → 2 H+ + 1/2 O2 + 2e- C- C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy D- C6H12O6 + 6 O2 → 6 CO2 + 12 H2O E- 6 CO2 + 6 H2O → C6H12O6 + 6 O2

E- ATP synthase phosphorylates ADP

Which of these phosphorylates ADP to make ATP? A C D B E

A- green

Which of these wavelengths/colors of visible light is LEAST useful for photosynthesis? A- green B- orange C- yellow D- blue

C- proton pumping

Which process in photosynthesis will be most directly compromised by inhibition of the cytochrome b6f complex? A- water splitting B- NADP+ reduction C- proton pumping Dx- carbon dioxide fixation

A- Photosynthesis Oxygen is a by-product of the photosynthetic process.

Which process produces oxygen? A- Photosynthesis B- Cellular respiration

B- The light-dependent reactions The light-dependent reactions use H2O and produce O2.

Which set of reactions uses H2O and produces O2? A- The light-independent reactions B- The light-dependent reactions

D- The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease

Which statement correctly describes how O2 production would be affected? (Assume that the light intensity does not change.) A- The rate of O2 production would decrease because the rate of G3P production by the Calvin cycle would decrease. B- The rate of O2 production would remain the same because the light intensity did not change. C- The rate of O2 production would remain the same because the light reactions are independent of the Calvin cycle. D- The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease.

D- Photophosphorylation The excitation of chlorophyll by light energy initiates a chain of events that leads to ATP production.

Which term describes ATP production resulting from the capture of light energy by chlorophyll? A- Oxidative phosphorylation B- Dephosphorylation C- Substrate-level phosphorylation D- Photophosphorylation

B- The energy released as electrons are passed along the electron transport chain is used to pump protons into the thylakoid compartment.

_____ releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment. A C B E D

A- Photosystem II splits water into 1/2 O2, H+, and e-

_____ splits water into 1/2 O2, H+, and e- . D B A C E