Chapter 10

Put these Calvin cycle events in order.

A CO2 molecule enters the cycle. Step 1 Rubisco catalyzes the fixation of CO2 to RuBP. Step 2 An unstable molecule splits into two molecules of 3-PGA. Step 3 An enzyme catalyzes the phosphorylation of 3-PGA. Step 4 An enzyme catalyses the reduction of 1,3BPGA by NADPH. Step 5 G3P molecules are rearranged to produce RuBP. Step 6 Photons excite pigment molecules. NOT A STEP

The Calvin cycle could not occur without the light reactions. Which of the following statements describes why this is the case?

ATP and NADPH produced in the light reactions provide the energy for the production of sugars in the Calvin cycle.

What do the light reactions of photosynthesis supply the Calvin cycle with?

ATP and NADPH.

Which occur in the thylakoids?

ATP production Light reactions

What happens during the first phase of the Calvin cycle?

CO2 is attached to RuBP.

Which occurs during the Calvin cycle?

CO2 is reduced.

What occurs in the stroma?

Carbon fixation Calvin cycle

Put the phases of the Calvin cycle in order.

Carbon fixation Phase 1 Reduction Phase 2 Regeneration Phase 3

Match each leaf structure with its characteristic.

Cell where photosynthesis takes place Mesophyll Internal membrane of a chloroplast Thylakoid Allow diffusion of CO2 Stomata Single unit of membranous sac Granum Organelle in which photosynthesis takes place Chloroplast Fluid inside a chloroplast Stroma

What property of the pigment chlorophyll makes it appear green?

Chlorophyll absorbs all of the visible spectrum of light except green, which it reflects.

What do the results of this experiment demonstrate?

Chlorophyll absorbs more blue light than green Photosynthesis should be higher in plants exposed to blue light rather than to green.

Which of the following processes occurs during the second phase of the Calvin cycle?

G3P production

Imagine that light reactions produced only half the ATP that they actually do. What would be required to maintain the Calvin cycle at the same rate?

More H2O

Where does the energy used to produce ATP in the light reactions of photosynthesis come from?

Movement of H+ through a membrane

The light reactions of photosynthesis generate high-energy electrons, which end up in __________. The light reactions also produce __________ and __________.

NADPH; ATP; oxygen

Regarding the Calvin cycle, which are correct?

Occurs in the stroma Uses ATP and NADPH Produces NADP+, ADP and Pi Uses CO2 and produces GP3. Occurs in the stroma, a dense fluid contained within the membranes of the chloroplast but outside the thylakoids Uses CO2 (via the stomata) and produces GP3, a type of sugar Uses ATP and NADPH, which are provided by the light reactions Produces NADP+, ADP and inorganic phosphate (), which are then used by the light reactions

In the light reactions of photosynthesis, ATP is produced by photophosphorylation. Which of the listed processes is most similar to photophosphorylation?

Oxidative phosphorylation

During light reactions, what is produced by linear electron flow?

Oxygen

Put these inputs, processes, and outputs of photosystem II in order.

Photons excite pigment molecules. Molecules transfer energy via molecular excitation. P680 gives up an electron. An enzyme catalyses the splitting of H2O. Electrons are passed down a transport chain, powering the production of ATP. Electrons are passed down a transport chain and NOT A STEP used to reduce NAD+ to NADPH.

Put these inputs, processes, and outputs of photosystem I in order.

Photons excite pigment molecules. Step 1 Molecules transfer energy via molecular excitation. Step 2 P700 gives up an electron. Step 3 Electrons passed down a transport chain replenish pigment molecules. Step 4 Electrons are passed down a transport chain and used to reduce NAD+ to NADPH. Step 5 An enzyme catalyzes the fixation of carbon provided by CO2. NOT A STEP

A photosystem consists of which of the following structures?

Primary electron acceptor Reaction-center complex Chlorophyll molecules Light-harvesting complexes

How does carbon dioxide enter a leaf?

Stomata

Put these leaf structures in order, from outermost to innermost.

Stomata 1 (Outermost) Chloroplast 3 Stroma 4 Mesophyll 2 Thylakoids 5 Chlorophyll 6 (Innermost)

Why do the reactions of the Calvin cycle usually not occur at night?

The Calvin cycle requires products of the photosystems.

During which process is molecular oxygen produced in photosynthesis?

The light reactions by linear electron flow

What happens when chloroplast pigments absorb light?

Their electrons become excited.

Why are most autotrophs referred to as the producers of the biosphere?

They are the ultimate sources of organic compounds for all nonautotrophic organisms.

The light reactions of photosynthesis use chemiosmosis to produce ATP that will be used in the Calvin cycle. The electrochemical gradient that drives this chemiosmosis is formed across which structure(s)?

Thylakoid membrane

Chlorophyll molecules are in which part of the chloroplast?

Thylakoid membranes

Regarding the light reactions phase of photosynthesis, which are correct?

Uses H2O and releases O2 Produces ATP and NADPH Uses NADP+, ADP and Pi Occurs in the thylakoid Uses light energy to excite electrons

Where do the electrons entering photosystem II come from?

Water

In photosynthesis, what molecule is oxidized and what molecule is reduced?

Water is oxidized and carbon dioxide is reduced.

You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. What has the plant been using for an energy source while in the dark?

While it did have access to light, the plant stored energy in the form of sugars or starch, and it was able to derive energy from the stored molecules during your vacation.

What is the most important role of pigments in photosynthesis?

capture light energy

What is the source of the carbon plants use to make organic molecules?

carbon dioxide

Which processes are used in both cellular respiration and photosynthesis?

electron transport chains chemiosmosis

Where does the Calvin cycle of photosynthesis occur?

stroma

Where do the light reactions of photosynthesis occur?

thylakoids

Both mitochondria and chloroplasts __________.

use chemiosmosis to produce ATP

What is the source of the oxygen produced by photosynthesis?

water