BSC1005 CH 5

The purple structure indicated by the arrow in the diagram is an enzyme called ______, which adds a phosphate to ADP using energy from a proton gradient.

ATP synthase

Place the following events in the correct order in which they occur during the electron transport chain between photosystem II and photosystem I. Start with the first event at the top.

1. The electron transport chain receives energized electrons from photosystem II. 2. The electrons are shuttled through a series of proteins in the thylakoid membrane. 3. The energy lost from the electrons drives the active transport of protons from the stroma into the thylakoid space. 4. The electrons arrive at photosystem I.

The ______ pigments of photosystems pass the captured photon energy to the reaction center.

Antenna

In the CAM pathway, stomata are _______ at night to let CO2 in when water loss is less and are ______ during the day while maintaining a high concentration of carbon dioxide in the chloroplasts

Blank 1: open or open only Blank 2: closed, shut, or not open

In C4 plants, the Calvin cycle takes place within sheath cells, which are not exposed directly to atmospheric oxygen and therefore rubisco binds more often to carbon dioxide, reducing photorespiration

Bundle

In the light-independent reactions of photosynthesis, the ______ is a series of reactions in which the first stable compound formed is a 3-carbon molecule (PGA).

C3 pathway

About 95% of plant species are ______ plants, which typically have a ______ efficiency rate of photosynthesis.

C3; low

When CO2 levels in C3 plant leaves are high (stomata are open), the ______ pathway is favored; when CO2 levels in C3 plant leaves are low and O2 levels are high (stomata are closed), the ______ pathway is favored.

C3; photorespiration

In what carbon fixation pathway is CO2 incorporated into malate during the night, and then released in chloroplasts during the day to drive the Calvin cycle in mesophyll cells?

CAM pathway

The light reactions produce _____, and the carbon reactions produce _____.

ATP and NADPH; glucose

A group of proteins in the thylakoid membrane that shuttles electrons between the proteins and other carriers is called a(n)

Electron Transport Blank 2: transport chain

What product of photosynthesis is used as a building block for the cellulose found in plant cell walls?

Glucose

What surround stomata in plant leaves and can collapse to close stomata and conserve water?

Guard cells

At the end of the electron transport chain of the light reactions, electrons reduce NADP+and form

NADPH

What is generated using the energy of electrons at the end of the electron transport chain in the light reactions of photosynthesis?

NADPH

The Calvin Cycle cannot proceed without the molecules ___, which are produced by the light reactions of photosynthesis.

NADPH and ATP

What photosystem functions first in the overall process of the light reactions in plants and algae?

Photosystem II

Chlorophyll and carotenoids are examples of ______, which are molecules that can absorb light energy.

Pigments

Select all of the following that describe CAM plants.

The Calvin cycle occurs during the day. CO2 is incorporated into malate in mesophyll cells. High concentrations of CO2 are maintained in chloroplasts during the day to favor the Calvin cycle.

As described in this chapter's Investigating Life essay, the eggs of some salamanders are infected with algae. Use your knowledge of photosynthesis products and reactants to predict what might be the effect of algae living in salamander eggs.

The algae would boost the O2 and glucose concentrations in the egg.

What statement accurately describes how the two photosystems function in the light reactions?

They function sequentially, with photosystem II acting first.

As described in this chapter's Investigating Life essay, algae living in salamander eggs transfer some sugars to the developing embryo. How did the researchers determine how much sugar the embryo received from the algae?

They tagged CO2 with a radioactive isotope and then measured how much carbon moved to the embryo.

Select all of the characteristics of C4 plants.

adapted to hot, sunny habitats require less water than C3 plants expend additional ATP to reduce photorespiration

In the carbon reactions of photosynthesis, carbon from ______ is used to produce sugar molecules using energy from ATP and electrons from NADPH.

carbon dioxide

Ribulose bisphosphate combines with CO2 in the initial ______ step of the Calvin cycle.

carbon fixation

ATP production using energy from a proton gradient across a membrane is called ______ phosphorylation.

chemiosmotic

ATP synthase produces ATP during photosynthesis and aerobic cellular respiration in a process called

chemiosmotic phosphorylation.

Select all of the examples of C4 plants.

crabgrass corn sugarcane

Select all of the conditions that favor the photorespiration reaction of rubisco in a C3plant.

higher O2 than CO2 concentration in leaves closed stomata

Select all of the conditions that favor the photorespiration reaction of rubisco in a C3 plant.

higher O2 than CO2 concentration in leaves closed stomata

If stomata close to conserve water, CO2 in the leaves decreases, and O2 increases, which causes the rate of photorespiration to

increase.

In C4 plants, CO2 is first fixed into a four-carbon molecule in ______ cells by an enzyme other than rubisco; then in the adjacent ______ cells, CO2 is liberated and can enter the Calvin cycle

mesophyll; bundle-sheath

C3 plants are plants that

only use the C3 pathway to fix carbon.

About 2.4 billion years ago, the gas ______ began to accumulate in Earth's atmosphere due to photosynthesis conducted by ancient ______.

oxygen; cyanobacteria

What three-carbon carbohydrate leaves the Calvin cycle and is used to build glucose and sucrose?

phosphoglyceraldehyde (PGAL)

Match the pathway with the correct description.

photorespiration matches , Oxygen is used by the enzyme rubisco in an energetically wasteful reaction. Oxygen is used by the enzyme rubisco in an energetically wasteful reaction. C3pathway matches Choice, Carbon dioxide is used by the enzyme rubisco to produce PGA. Carbon dioxide is used by the enzyme rubisco to produce PGA. C4 photosynthesis matches Choice, Carbon dioxide is used to produce oxaloacetate, and the Calvin cycle takes place in bundle-sheath cells. Carbon dioxide is used to produce oxaloacetate, and the Calvin cycle takes place in bundle-sheath cells. CAM photosynthesis matches Choice, Carbon dioxide is incorporated into a 4-carbon molecule at night, and the Calvin cycle takes place during the day in mesophyll cells. Carbon dioxide is incorporated into a 4-carbon molecule at night, and the Calvin cycle takes place during the day in mesophyll cells.

The enzyme rubisco adds oxygen instead of carbon dioxide to RuBP in a process called

photorespiration.

The C4 and CAM pathways minimize ______ rate by increasing _______ concentrations encountered by rubisco.

photorespiration; CO2

Select all the components of the photosynthetic electron transport chain.

photosystem II enzyme that produces NADPH photosystem I proton pump protein

In photosystem I, electrons ejected from the reaction center are replaced with electrons passed down the electron transport chain from

photosystem II.

In algae and plants, ______ has a peak light absorption at wavelength of 680 nm, and ______ has a peak light absorption at a wavelength of 700 nm.

photosystem II; photosystem I

In photosynthesis, the reactant ______ is oxidized, and the reactant ______ is reduced.

water; carbon dioxide

In the thylakoid membrane, an enzyme complex called ATP ______ uses energy from protons passing through it to synthesize ATP.

synthase

While the C4 and CAM pathways have limitations, these adaptations allow ______ to continue in C4 and CAM plants even when stomata are closed during the hottest times of the day.

the Calvin cycle

During the photosynthetic electron transport chain, protons are pumped into the ______ from the stroma and then pass back to the stroma through ______ channels, which are enzyme complexes that can use the energy released from the protons to generate ATP.

thylakoid space; ATP synthase

In the first step of the Calvin cycle, ______ becomes incorporated into an organic compound, which is a process called ______.

CO2; carbon fixation

Select all of the following that are alternate names for the carbon reactions of photosynthesis.

Calvin cycle dark reactions light-independent reactions

The enzyme rubisco catalyzes the first step in the

Calvin cycle.

What occurs during photorespiration that stops the Calvin cycle from proceeding?

Rubisco adds oxygen instead of carbon dioxide to RuBP.

Select all of the molecules that are reactants of photosynthesis.

Water (H2O) Carbon dioxide (CO2)

Select all the examples of CAM plants.

cacti pineapple

A ______ gradient is created across the thylakoid membrane using energy from electrons as they pass along the electron transport chain between photosystem II and photosystem I.

proton

The enzyme that combines CO2 and RuBP is known as

rubisco.

Where do the carbon reactions of photosynthesis take place?

stroma within a chloroplast