Chapter 10 Photosynthesis Questions Bio 212

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

420 nm

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

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

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

ATP and NADPH

The light reactions of photosynthesis supply the Calvin cycle with

ATP and NADPH.

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

An electron is excited.

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.

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.

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

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.

Why might the alternative pathways of photosynthesis using C4 or CAM systems be described as metabolic compromises?

Both pathways minimize photorespiration but also expend more ATP during carbon fixation.

What would be the expected effect on plants if the atmospheric CO2 concentration was doubled?

C3 plants would have faster growth rates; C4 plants would be minimally affected.

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.

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.

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

H2O → NADPH → Calvin cycle

How is photosynthesis similar in C4 plants and CAM plants?

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

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.

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.

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

It produces carbon dioxide and consumes ATP and oxygen.

Which of the following statements is true concerning the accompanying figure?

It represents a C4 photosynthetic system.

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

NADP+

The reducing power for Calvin cycle reactions is provided by which of the following molecules?

NADPH

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.

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.

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.

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.

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.

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

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

What would be a likely consequence of a mutation in plants that results in a photorespiration deficiency?

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

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.

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

They are inversely related.

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.

Why are C4 plants able to photosynthesize with no apparent photorespiration?

They use PEP carboxylase to initially fix CO2.

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.

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

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

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

Compared to C3 plants, C4 plants ________.

can continue to fix CO2 even at lower CO2 concentrations and higher oxygen concentrations

Referring to the accompanying figure, where would elevated concentrations of oxygen inhibit carbon fixation reactions?

cell II only

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

CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they ________.

fix CO2 into organic acids during the night

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

) 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

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

neither photosynthesis nor respiration

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.

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

photosynthesis and respiration

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

receiving electrons from the thylakoid membrane electron transport chain

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

Which of the following processes occurs during the Calvin cycle?

regeneration of the CO2 acceptor

Which of the following does not occur during the Calvin cycle?

release of oxygen

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

removal of electrons from chlorophyll molecules

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

splitting water molecules

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

stroma of the chloroplast

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

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 produce molecular oxygen (O2)?

the light reactions alone

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

Where are ATP synthase complexes located in plant cells?

thylakoid membrane and inner mitochondrial membrane

Which process is most directly driven by light energy?

transfer of energy from pigment molecule to pigment molecule