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

H2O → NADPH → Calvin cycle

To identify the molecule that accepts CO2, Calvin and Benson manipulated the carbon-fixation cycle by either cutting off CO2 or cutting off light from cultures of photosynthetic algae. They then measured the concentrations of various metabolites immediately following the manipulation. How would these experiments help identify the CO2 acceptor?

The CO2 acceptor concentration would increase when the CO2 is cut off, but decrease when the light is cut off.

Use the following figure to answer the question.

Refer to the accompanying figure and the molecules labeled A, B, C, D, and E. If the carbon atom of each of the incoming CO2 molecules is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?

B, C, D, and E

In the initial step in carbon fixation, a molecule of CO2 is attached to RuBP to produce a six-carbon molecule, which is immediately split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to occur to complete the Calvin cycle?

regeneration of RuBP

Where in a plant cell does the Calvin cycle take place?

stroma of the chloroplast

Which of the following molecules are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

ATP and NADPH

A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights that is set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask. The dissolved oxygen in the flask with algae will ________.

be higher in the light, but lower in the dark

A gardener is concerned that her greenhouse is getting too hot from too much light and seeks to shade her plants with colored translucent plastic sheets, the color of which allows passage of only that wavelength. What color should she use to reduce overall light energy but still maximize plant growth?

blue

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

removal of electrons from chlorophyll molecules

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

oxidative phosphorylation in cellular respiration

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

the light reactions alone

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?

They protect against oxidative damage from excessive light energy.

P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?

It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.

What is the relationship between the wavelength of light and the quantity of energy per photon?

They are inversely related.

Carbon dioxide is split to form oxygen gas and carbon compounds in which of the following metabolic pathways?

neither photosynthesis nor respiration

In photosynthetic cells, synthesis of ATP by chemiosmosis occurs during ________.

photosynthesis and respiration

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.

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

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

In mitochondria, an electron transport chain pumps protons from the matrix into the intermembrane space, whereas in chloroplasts, an electron transport chain pumps protons from the ________.

stroma to the thylakoid space

Where are ATP synthase complexes located in plant cells?

thylakoid membrane and inner mitochondrial membrane

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

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in one hour. You find that 30,000 molecules of ATP were consumed, but only 20,000 molecules of NADPH were consumed. What is the source of the extra ATP molecules?

cyclic electron flow

What are the products of cyclic electron flow during the light reactions of photosynthesis?

ATP

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

ATP and NADPH

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. Which of the following approaches would be the best way to detect the lack of photosystem II in these organisms?

Determine whether they produce O2 in the light.

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

receiving electrons from the thylakoid membrane electron transport chain

What is 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.

Which molecule is the final electron acceptor for electrons from photosystem I?

NADP+

What happens to the free energy released as electrons are passed from photosystem II to photosystem I through a series of electron carriers?

It is used to establish and maintain a proton gradient.

Which of the following events accompanies absorption of energy by chlorophyll molecules of the reaction-center complex?

An electron is excited.

In autumn, chlorophyll is degraded in the leaves of deciduous trees. Why do the leaves change color to shades of yellow, orange, or red?

Other pigments such as carotenoids are still present in the leaves.

Paper chromatography is a technique used to separate molecules based upon their size and solubility in a particular solvent. If pigments from a particular species of plant are extracted and subjected to paper chromatography, which of the following results is most likely?

Paper chromatography would separate the pigments into several bands that appear green or yellow/orange.

Why are the reaction centers of photosystems composed of several structurally different pigments?

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

Use the following figure to answer the question.

Halobacterium has a photosynthetic membrane that appears purple. Its photosynthetic action spectrum is the inverse of the action spectrum for green plants (see figure). That is, the Halobacterium action spectrum has a peak where the green plant action spectrum has a trough. What wavelengths of light do the Halobacterium photosynthetic pigments absorb?

green and yellow

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. Suppose a plant has a unique photosynthetic pigment and the leaves of this plant appear to be reddish yellow. What wavelengths of visible light are absorbed by this pigment?

blue and violet

A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed. What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure?

a mixture of blue and red light

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. Which of the following statements describes a relationship that Engelmann's experiment helped to determine?

the relationship between wavelength of light and the rate of photosynthesis

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. What did Engelmann conclude about the congregation of bacteria in the red and blue areas?

Bacteria congregated in these areas because these areas had the most oxygen being released.

Use the following figure to answer the question.

What wavelength of light in the figure is most effective in driving photosynthesis?

420 nm

Use the following figure to answer the question.

The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?

Other pigments absorb light in addition to chlorophyll a.

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

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

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

splitting water molecules

Use the following figure to answer the question.

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) will fail to contain 18O in later biochemical analyses?

ADP

Under what conditions do photosynthesis and cellular respiration occur in plants?

Photosynthesis occurs only in the light, and cellular respiration occurs in both the dark and the light.

In autotrophic bacteria, where is chlorophyll located?

in infolded regions of the plasma membrane

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

in prokaryotes