Question 1

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?

Accepted Answer

A)  The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP,i, and NADP+ to the light reactions. 
B)  The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. 
C)  The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP. 
D)  The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split. 
E)  There is no relationship between the light reactions and the Calvin cycle. 
A)  The light reactions provide ATP and NADPH to the Calvin cycle, and the Calvin cycle returns ADP,i, and NADP+ to the light reactions. 
B)  The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. 
C)  The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP. 
D)  The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split. 
E)  There is no relationship between the light reactions and the Calvin cycle.

Question 2

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

Accepted Answer

A)  They serve as accessory pigments to increase light absorption. 
B)  They protect against oxidative damage from excessive light energy. 
C)  They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation. 
D)  They reflect orange light and enhance red light absorption by chlorophyll. 
E)  They take up and remove toxins from the groundwater. 
A)  They serve as accessory pigments to increase light absorption. 
B)  They protect against oxidative damage from excessive light energy. 
C)  They shield the sensitive chromosomes of the plant from harmful ultraviolet radiation. 
D)  They reflect orange light and enhance red light absorption by chlorophyll. 
E)  They take up and remove toxins from the groundwater.

Question 3

In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and ________.

Accepted Answer

A)  carotenoids and other pigments are still present in the leaves 
B)  the degraded chlorophyll changes into many other colors 
C)  water supply to the leaves has been reduced 
D)  sugars are sent to most of the cells of the leaves 
A)  carotenoids and other pigments are still present in the leaves 
B)  the degraded chlorophyll changes into many other colors 
C)  water supply to the leaves has been reduced 
D)  sugars are sent to most of the cells of the leaves

Question 4

The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find?

Accepted Answer

A)  The pH within the thylakoid is less than that of the stroma. 
B)  The pH of the stroma is lower than that of the other two measurements. 
C)  The pH of the stroma is higher than that of the thylakoid space but lower than that of the cytosol. 
D)  The pH of the thylakoid space is higher than anywhere else in the cell. 
E)  There is no consistent relationship. 
A)  The pH within the thylakoid is less than that of the stroma. 
B)  The pH of the stroma is lower than that of the other two measurements. 
C)  The pH of the stroma is higher than that of the thylakoid space but lower than that of the cytosol. 
D)  The pH of the thylakoid space is higher than anywhere else in the cell. 
E)  There is no consistent relationship.

Question 5

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during ________.

Accepted Answer

A)  photosynthesis only 
B)  respiration only 
C)  photosynthesis and respiration 
D)  neither photosynthesis nor respiration 
E)  photorespiration only 
A)  photosynthesis only 
B)  respiration only 
C)  photosynthesis and respiration 
D)  neither photosynthesis nor respiration 
E)  photorespiration only

Question 6

The chemiosmotic process in chloroplasts involves the ________.

Accepted Answer

A)  establishment of a proton gradient across the thylakoid membrane 
B)  diffusion of electrons through the thylakoid membrane 
C)  reduction of water to produce ATP 
D)  movement of water by osmosis into the thylakoid space from the stroma 
E)  formation of glucose, using carbon dioxide, NADPH, and ATP 
A)  establishment of a proton gradient across the thylakoid membrane 
B)  diffusion of electrons through the thylakoid membrane 
C)  reduction of water to produce ATP 
D)  movement of water by osmosis into the thylakoid space from the stroma 
E)  formation of glucose, using carbon dioxide, NADPH, and ATP

Question 7

The light-independent reactions of plants function to make organic molecules using carbon dioxide as a carbon source. What is the electron source that helps reduce carbon dioxide to sugars and other organic molecules?

Accepted Answer

A)  NADH 
B)  NADPH 
C)  ATP 
D)  electrons from oxygen 
A)  NADH 
B)  NADPH 
C)  ATP 
D)  electrons from oxygen

Question 8

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

Accepted Answer

A)  Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain. 
B)  This arrangement enables the plant to absorb light energy of a variety of wavelengths. 
C)  They enable the plant to absorb more photons from light energy, all of which are at the same wavelength. 
D)  They enable the reaction center to excite electrons to a higher energy level. 
A)  Excited electrons must pass through several pigments before they can be transferred to electron acceptors of the electron transport chain. 
B)  This arrangement enables the plant to absorb light energy of a variety of wavelengths. 
C)  They enable the plant to absorb more photons from light energy, all of which are at the same wavelength. 
D)  They enable the reaction center to excite electrons to a higher energy level.

Question 9

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

Accepted Answer

A)  It is the receptor for the most excited electron in either photosystem of photosynthesis. 
B)  It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system. 
C)  It transfers its electrons to reduce NADP+ to NADPH. 
D)  It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has. 
E)  It obtains carbon from a sugar molecule, so it must have a stronger attraction for electrons than either oxygen or hydrogen. 
A)  It is the receptor for the most excited electron in either photosystem of photosynthesis. 
B)  It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system. 
C)  It transfers its electrons to reduce NADP+ to NADPH. 
D)  It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has. 
E)  It obtains carbon from a sugar molecule, so it must have a stronger attraction for electrons than either oxygen or hydrogen.

Question 10

Reactions that require CO2 take place in ________.

Accepted Answer

A)  the light reactions alone 
B)  the Calvin cycle alone 
C)  both the light reactions and the Calvin cycle 
D)  neither the light reactions nor the Calvin cycle 
E)  the chloroplast, but not as part of photosynthesis 
A)  the light reactions alone 
B)  the Calvin cycle alone 
C)  both the light reactions and the Calvin cycle 
D)  neither the light reactions nor the Calvin cycle 
E)  the chloroplast, but not as part of photosynthesis

Question 11

What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?

Accepted Answer

A)  ATP is synthesized from the energy absorbed. 
B)  A carboxylation reaction of the Calvin cycle occurs. 
C)  Electrons are stripped from NADPH. 
D)  An electron is excited. 
A)  ATP is synthesized from the energy absorbed. 
B)  A carboxylation reaction of the Calvin cycle occurs. 
C)  Electrons are stripped from NADPH. 
D)  An electron is excited.

Question 12

Use the following information to answer the question(s) below.
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 would be the expected effect on plants if the atmospheric CO2 concentration was doubled?

Accepted Answer

A)  All plants would experience increased rates of photosynthesis. 
B)  C3 plants would have faster growth; C4 plants would be minimally affected. 
C)  C4 plants would have faster growth; C3 plants would be minimally affected. 
D)  C3 plants would have faster growth; C4 plants would have slower growth. 
E)  Plant growth would not be affected because atmospheric CO2 concentrations are never limiting for plant growth. 
A)  All plants would experience increased rates of photosynthesis. 
B)  C3 plants would have faster growth; C4 plants would be minimally affected. 
C)  C4 plants would have faster growth; C3 plants would be minimally affected. 
D)  C3 plants would have faster growth; C4 plants would have slower growth. 
E)  Plant growth would not be affected because atmospheric CO2 concentrations are never limiting for plant growth.

Question 13

Where do the enzymatic reactions of the Calvin cycle take place?

Accepted Answer

A)  stroma of the chloroplast 
B)  thylakoid membranes 
C)  matrix of the mitochondria 
D)  cytosol around the chloroplast 
E)  thylakoid space 
A)  stroma of the chloroplast 
B)  thylakoid membranes 
C)  matrix of the mitochondria 
D)  cytosol around the chloroplast 
E)  thylakoid space

Question 14

Use the accompanying figure and the molecules labeled A, B, C, D, and E to answer the following questions.   Refer to the figure. 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?

Accepted Answer

A)  The CO2 acceptor concentration would decrease when either the CO2 or light is cut off. 
B)  The CO2 acceptor concentration would increase when either the CO2 or light is cut off. 
C)  The CO2 acceptor concentration would increase when the CO2 is cut off but decrease when the light is cut off. 
D)  The CO2 acceptor concentration would decrease when the CO2 is cut off but increase when the light is cut off. 
E)  The CO2 acceptor concentration would stay the same regardless of the CO2 or light. 
A)  The CO2 acceptor concentration would decrease when either the CO2 or light is cut off. 
B)  The CO2 acceptor concentration would increase when either the CO2 or light is cut off. 
C)  The CO2 acceptor concentration would increase when the CO2 is cut off but decrease when the light is cut off. 
D)  The CO2 acceptor concentration would decrease when the CO2 is cut off but increase when the light is cut off. 
E)  The CO2 acceptor concentration would stay the same regardless of the CO2 or light.

Question 15

Which of the events listed below occurs in the light reactions of photosynthesis?

Accepted Answer

A)  NADP is produced. 
B)  NADPH is reduced to NADP+. 
C)  Carbon dioxide is incorporated into PGA. 
D)  ATP is phosphorylated to yield ADP. 
E)  Light is absorbed and funneled to reaction-center chlorophyll a. 
A)  NADP is produced. 
B)  NADPH is reduced to NADP+. 
C)  Carbon dioxide is incorporated into PGA. 
D)  ATP is phosphorylated to yield ADP. 
E)  Light is absorbed and funneled to reaction-center chlorophyll a.

Question 16

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

Accepted Answer

A)  fix CO2 into organic acids during the night 
B)  fix CO2 into sugars in the bundle-sheath cells 
C)  fix CO2 into pyruvate in the mesophyll cells 
D)  use the enzyme phosphofructokinase, which outcompetes rubisco for CO2 
E)  use photosystem I and photosystem II at night 
A)  fix CO2 into organic acids during the night 
B)  fix CO2 into sugars in the bundle-sheath cells 
C)  fix CO2 into pyruvate in the mesophyll cells 
D)  use the enzyme phosphofructokinase, which outcompetes rubisco for CO2 
E)  use photosystem I and photosystem II at night

Question 17

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find that 30,000 molecules of ATP were consumed, but only 20,000 molecules of NADPH were consumed. Where did the extra ATP molecules come from?

Accepted Answer

A)  photosystem II 
B)  photosystem I 
C)  cyclic electron flow 
D)  linear electron flow 
E)  chlorophyll 
A)  photosystem II 
B)  photosystem I 
C)  cyclic electron flow 
D)  linear electron flow 
E)  chlorophyll

Question 18

Photorespiration ________.

Accepted Answer

A)  generates carbon dioxide and consumes ATP and oxygen 
B)  generates ATP and sugars and consumes oxygen and carbon dioxide 
C)  generates oxygen and consumes ATP, carbon dioxide, and sugars 
D)  consumes carbon dioxide and generates ATP, sugars, and oxygen 
A)  generates carbon dioxide and consumes ATP and oxygen 
B)  generates ATP and sugars and consumes oxygen and carbon dioxide 
C)  generates oxygen and consumes ATP, carbon dioxide, and sugars 
D)  consumes carbon dioxide and generates ATP, sugars, and oxygen

Exam 10: Photosynthesis

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?

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

In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and ________.

The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find?

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during ________.

The chemiosmotic process in chloroplasts involves the ________.

The light-independent reactions of plants function to make organic molecules using carbon dioxide as a carbon source. What is the electron source that helps reduce carbon dioxide to sugars and other organic molecules?

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

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

Reactions that require CO2 take place in ________.

What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?

Where do the enzymatic reactions of the Calvin cycle take place?

Which of the events listed below occurs in the light reactions of photosynthesis?

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

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find that 30,000 molecules of ATP were consumed, but only 20,000 molecules of NADPH were consumed. Where did the extra ATP molecules come from?

Photorespiration ________.

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Ecosystems and Global Ecology

Lipids, Membranes, and the First Cells

Inside the Cell

Energy and Enzymes: an Introduction to Metabolism

Cellular Respiration and Fermentation

Cellcell Interactions

The Cell Cycle

Meiosis

Mendel and the Gene

Dna and the Gene: Synthesis and Repair

How Genes Work

Transcription, Rna Processing, and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

The Molecular Revolution: Biotechnology and Beyond

Genes, Development, and Evolution

Evolution by Natural Selection

Evolutionary Processes

Speciation

Phylogenies and the History of Life

Bacteria and Archaea

Protists

Green Algae and Land Plants

Fungi

An Introduction to Animals

Protostome Animals

Deuterostome Animals

Viruses

Plant Form and Function

Water and Sugar Transport in Plants

Plant Nutrition

Plant Sensory Systems, Signals, and Responses

Plant Reproduction and Development

Animal Form and Function

Water and Electrolyte Balance in Animals

Animal Nutrition

Gas Exchange and Circulation

Animal Nervous Systems

Animal Sensory Systems

Animal Movement

Chemical Signals in Animals

Animal Reproduction and Development

The Immune System in Animals

An Introduction to Ecology

Behavioral Ecology

Population Ecology

Community Ecology

Biodiversity and Conservation Biology

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