bio 101 ch. 10: photosynthesis and cellular respiration cont.

How many electrons at a time are passed between the pigment molecules in the light-harvesting complexes?

0

For every molecule of O2 that is released by photosystem II, 2 H2O molecules are needed, which together pass 4 electrons to the PS II reaction-center complex.

2, 4

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

3

Approximately what wavelength of light is best absorbed by chlorophyll a, the pigment that participates directly in the light reactions?

435nm

Which wavelength of light is best absorbed by chlorophyll b?

455nm

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

6

Which of these equations best summarizes photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), which of the following molecules produced by the algae (refer to the accompanying figure) would be least likely to contain 18O in subsequent analyses?

ADP

The light reactions supply the Calvin cycle with

ATP and NADPH

What are the products of linear electron flow in the light reactions of photosynthesis?

ATP and NADPH

Which of the following statements best summarizes the metabolic results of photorespiration?

ATP is hydrolyzed, carbon dioxide is produced, and oxygen is consumed.

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?

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

Which of the following events is most immediately associated with the absorption of energy by chlorophyll molecules of the reaction-center complex?

An electron is excited.

Which of the following statements is a correct distinction between autotrophs and heterotrophs?

Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other nutrients that are inorganic.

What is the basic role of CO2 in photosynthesis?

CO2 is fixed or incorporated into organic molecules.

Why is it correct to say that the linear electron flow of the light reactions directly captures energy in NADPH but only indirectly captures energy in ATP?

Electrons are directly transferred to NADP+ to form NADPH, but electron flow is used to generate a proton gradient for ATP synthesis. Electrons are not directly transferred to ATP.

What happens along an electron transport chain?

Electrons are passed from a reducing agent to an oxidizing agent, releasing free energy at each step.

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

G3P

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

H2O → NADPH→ Calvin cycle

Which of the following is the correct order of electron flow in the light reactions of photosynthesis?

H2O → P680 chlorophyll a pair → PS II primary electron acceptor → Pq → cytochrome complex → Pc → P700 chlorophyll a pair → PS I primary electron acceptor → Fd → NADPH

How is photosynthesis similar in C4 plants and CAM plants?

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

A flask containing photosynthetic green algae and a control flask containing only water are exposed to a cycle of 12 hours of light and 12 hours of darkness. Which of the following statements best describes how the relative dissolved oxygen concentration in the flask with algae will compare to the control flask?

It will be lower in the control in the light, but higher in the control in the dark.

Which of the following molecules is the final electron acceptor for electrons from photosystem I?

NADP+

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

NADPH

Which of the following molecules is the primary product of photosystem I?

NADPH

Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?

NADPH

If the Calvin cycle slows down, what will happen to the rate of O2 production in PS II, and why?

O2 production will slow down because less NADP+ will be regenerated in the Calvin cycle.

Can you tell from these absorption spectra whether red light is effective in driving photosynthesis?

One cannot tell from this graph, but because chlorophyll a does absorb red light, we can predict that it would be effective in driving photosynthesis.

Which of the following statements correctly describes a distinction between autotrophs and heterotrophs?

Only autotrophs can produce organic molecules from CO2 and other inorganic materials.

In autumn, chlorophyll is degraded in the leaves of deciduous trees. Which of the following statements best explains the change in color from green to shades of yellow, orange, or red?

Other pigments such as carotenoids remain in the leaves after the chlorophyll is degraded.

Which of the following statements best describes the relationship between photosynthesis and cellular respiration?

Photosynthesis stores energy in complex organic molecules; cellular respiration releases energy from complex organic molecules.

Why are plants classified as producers?

Plants are classified as producers because they fix inorganic carbon into organic molecules.

Carbon fixation involves the addition of carbon dioxide to _____.

RuBP

Which molecule is regenerated in the regeneration phase of the Calvin cycle? Without regeneration of this molecule, the Calvin cycle would stop.

RuBP

Select the correct statement about the Calvin cycle.

The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RuBP.

Select the most accurate statement describing the basic function of the light reactions of photosynthesis.

The basic function of the light reactions of photosynthesis is the conversion of solar energy to chemical energy.

Which of the following statements is true of most cellular redox reactions?

The electron acceptor is reduced, acting as an oxidizing agent.

When a pigment molecule in a light-harvesting complex absorbs a photon of light, what happens to its excited-state electron?

The electron falls back to its ground state, while passing its excited-state energy to an electron in a nearby pigment molecule.

If only chlorophyll a were involved in the light reactions, would blue light (wavelength about 490 nm) be effective in driving photosynthesis?

The graph indicates that chlorophyll a absorbs very little blue light, so we can predict that blue light would not be effective.

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?

The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?

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

Which of the following events are associated with chemiosmosis in chloroplasts?

The pH of the thylakoid space increases and ATP is synthesized.

A mutation that eliminates a plant's ability to perform photorespiration will most likely have which of the following effects on the plant?

There would be more cellular damage from harmful products of the light reactions of photosynthesis.

An action spectrum plots the rate of photosynthesis at various wavelengths of visible light, and it shows that blue light with a wavelength of about 490 nm is effective in driving photosynthesis. Based on this information and the absorption spectra shown at left, what role may chlorophyll b and carotenoids play in photosynthesis?

These pigments are able to absorb more wavelengths of light (and thus more energy) than chlorophyll a alone can absorb. As part of light-harvesting complexes in photosystems, they broaden the range of light that can be used in the light reactions.

Which of the following describes the function of the pigment molecules in a light-harvesting complex in the thylakoid membranes?

They absorb and transfer light energy to the reaction-center chlorophyll.

You obtain the pigments called carotenoids in your diet when you eat carrots. Why do carotenoids appear yellow and orange?

They absorb blue/green light and reflect yellow and red wavelengths of light.

Which of the following statements best describes the relationship between the wavelength of light and the quantity of energy per photon?

They are inversely related.

What is the biological significance of the light-independent reactions of photosynthesis?

They convert carbon dioxide to sugar.

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. Which of the following statements best describes a related function they serve in plants?

They protect against oxidative damage from excessive light energy.

Plants are photoautotrophs. What does this mean?

They use light energy to drive the synthesis of organic molecules from inorganic materials.

Which of the following statements describes a primary benefit of having photosystem reaction centers composed of several structurally different pigments?

This arrangement enables the plant to absorb light energy of a variety of wavelengths.

On a spaceship designed to support a multiyear voyage to the outer planets of the solar system, plants will be grown to provide oxygen and to recycle carbon dioxide. Because the spaceship will be so far from the sun, an artificial light source will be needed to support photosynthesis. Which of the following wavelengths of light should be used to maximize plant growth?

a mixture of blue and red light

Which of the following occurs during the Calvin cycle?

carbon fixation

The photosynthetic membranes are found in the __________ in plant cells.

chloroplast

When light strikes chlorophyll molecules of PS II, they lose electrons, which are ultimately replaced by __________.

electrons released by splitting water

Which of the following processes is driven by the free energy released as electrons move through photosystem II and I in the thylakoid membranes?

establishment of a proton gradient

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.

false

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

false

Which set of reactions uses H2O and produces O2?

light dependent reactions

P680+ is said to be the strongest biological oxidizing agent. The strong oxidizing potential of P680+ is essential for its function because it ________.

obtains electrons from the oxygen atom in a water molecule

Which of the following processes is most directly driven by light energy?

oxidation of chlorophyll molecules

The mechanism of photophosphorylation is most similar to which of the following processes?

oxidative phosphorylation in cellular respiration

In mechanism, photophosphorylation is most similar to

oxidative phosphorylation in cellular respiration.

Photosynthesis is a redox reaction. H2O is __________ during the light reactions and CO2 is __________ during the Calvin cycle.

oxidized, reduced

Which of the following is(are) produced by the light reactions of photosynthesis?

oxygen, ATP, and NADPH

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

photophosphorlyation

Which process produces oxygen?

photosynthesis

ATP is synthesized in plant cells by chemiosmosis in which of the following processes?

photosynthesis and cellular respiration

In which of the following organisms did the process of photosynthesis most likely originate?

prokaryotes

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

proton gradient

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

protons

Which of the following processes is directly associated with photosystem I?

receiving electrons from the thylakoid membrane electron transport chain

_____ has a longer wavelength than _____.

red and green

Paper chromatography is a technique used to separate molecules based upon their polarity. If pigments from oak leaves are extracted and subjected to paper chromatography, which of the following statements best describes the pigment bands that would be observed?

several bands that appear green, yellow, or orange

The oxygen released by photosynthesis is produced by which of the following processes?

splitting water molecules

The ultimate source of energy to support most life on Earth is __________.

sunlight

Which of the following processes would be most directly affected if a thylakoid membrane is punctured so that the interior of the thylakoid is no longer separated from the stroma?

synthesis of ATP

In a plant, which of the following reactions produces molecular oxygen (O2)?

the light reactions alone

If various plant cell membranes are isolated and incubated with a proton gradient across the isolated membrane in the presence of ADP and Pi, which of the following samples are most likely to be able to synthesize ATP?

thylakoid membrane and inner mitochondrial membrane

Which process is most directly driven by light energy?

transfer of energy from pigment molecule to pigment molecule

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

true

In the electromagnetic spectrum, the type of radiation that we call visible light occurs between __________.

ultraviolet radiation and infrared radiation

A plant with unique photosynthetic pigments has leaves that appear reddish yellow. Which of the following wavelengths of visible light are most effectively absorbed by this pigment?

violet and blue

The light reactions of photosynthesis use _____ and produce _____.

water ... NADPH

When a filament of algae is illuminated with light that is passed through a prism, different segments of algae are exposed to different wavelengths of light. When aerobic bacteria are present, they congregate in highest concentrations in the areas illuminated by the red and blue light. These data suggest a relationship between which of the following variables?

wavelength of light and the rate of photosynthesis