Question 1

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

Accepted Answer

A)  Both pathways increase the rate of photosynthesis but also increase the rate of water loss. 
B)  The CAM pathway allows more CO₂ into the plant but also increases the rate of water loss. 
C)  The C₄ pathway decreases water loss but also increases the rate of photorespiration. 
D)  Both pathways minimize photorespiration but also expend more ATP during carbon fixation. 
A)  Both pathways increase the rate of photosynthesis but also increase the rate of water loss. 
B)  The CAM pathway allows more CO₂ into the plant but also increases the rate of water loss. 
C)  The C₄ pathway decreases water loss but also increases the rate of photorespiration. 
D)  Both pathways minimize photorespiration but also expend more ATP during carbon fixation.

Question 2

In mechanism, photophosphorylation is most similar to

Accepted Answer

A)  substrate-level phosphorylation in glycolysis. 
B)  oxidative phosphorylation in cellular respiration. 
C)  carbon fixation. 
D)  reduction of NADP⁺. 
A)  substrate-level phosphorylation in glycolysis. 
B)  oxidative phosphorylation in cellular respiration. 
C)  carbon fixation. 
D)  reduction of NADP⁺.

Question 3

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. 
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.

Question 4

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

Accepted Answer

A)  Photosynthesis and cellular respiration occur only in the light. 
B)  Photosynthesis occurs only in the light, and cellular respiration occurs only in the dark. 
C)  Photosynthesis occurs only in the light, and cellular respiration occurs in both the dark and the light. 
D)  Photosynthesis and cellular respiration occur in both the dark and the light. 
A)  Photosynthesis and cellular respiration occur only in the light. 
B)  Photosynthesis occurs only in the light, and cellular respiration occurs only in the dark. 
C)  Photosynthesis occurs only in the light, and cellular respiration occurs in both the dark and the light. 
D)  Photosynthesis and cellular respiration occur in both the dark and the light.

Question 5

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

Accepted Answer

A)  carbon fixation 
B)  oxidation of NADPH 
C)  release of oxygen 
D)  regeneration of the CO₂ acceptor 
A)  carbon fixation 
B)  oxidation of NADPH 
C)  release of oxygen 
D)  regeneration of the CO₂ acceptor

Question 6

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

Accepted Answer

A)  CO₂ and glucose 
B)  H₂O and O₂ 
C)  ADP,   ᵢ, and NADP⁺ 
D)  ATP and NADPH 
A)  CO₂ and glucose 
B)  H₂O and O₂ 
C)  ADP,   ᵢ, and NADP⁺ 
D)  ATP and NADPH

Question 7

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?

Accepted Answer

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

Question 8

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

Accepted Answer

A)  substrate-level phosphorylation in glycolysis 
B)  oxidative phosphorylation in cellular respiration 
C)  the Calvin cycle 
D)  reduction of NADP⁺ 
A)  substrate-level phosphorylation in glycolysis 
B)  oxidative phosphorylation in cellular respiration 
C)  the Calvin cycle 
D)  reduction of NADP⁺

Question 9

Compared to C₃ plants, C₄ plants ________.

Accepted Answer

A)  can continue to fix CO₂ even at lower CO₂ concentrations and higher oxygen concentrations 
B)  have higher rates of photorespiration 
C)  do not use rubisco for carbon fixation 
D)  make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria 
A)  can continue to fix CO₂ even at lower CO₂ concentrations and higher oxygen concentrations 
B)  have higher rates of photorespiration 
C)  do not use rubisco for carbon fixation 
D)  make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria

Question 10

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

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)  This arrangement enables the plant to absorb more photons from light energy, all of which are at the same wavelength. 
D)  This arrangement enables 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)  This arrangement enables the plant to absorb more photons from light energy, all of which are at the same wavelength. 
D)  This arrangement enables the reaction center to excite electrons to a higher energy level.

Question 11

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 ________.

Accepted Answer

A)  always be higher 
B)  always be lower 
C)  be higher in the light, but the same in the dark 
D)  be higher in the light, but lower in the dark 
A)  always be higher 
B)  always be lower 
C)  be higher in the light, but the same in the dark 
D)  be higher in the light, but lower in the dark

Question 12

How is photosynthesis similar in C₄ plants and CAM plants?

Accepted Answer

A)  In both cases, only photosystem I is used. 
B)  Both types of plants make sugar without the Calvin cycle. 
C)  In both cases, rubisco is not used to fix carbon initially. 
D)  Both types of plants make most of their sugar in the dark. 
A)  In both cases, only photosystem I is used. 
B)  Both types of plants make sugar without the Calvin cycle. 
C)  In both cases, rubisco is not used to fix carbon initially. 
D)  Both types of plants make most of their sugar in the dark.

Question 13

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

Accepted Answer

A)  It excites electrons of the reaction center in photosystem I. 
B)  It is used to establish and maintain a proton gradient. 
C)  It is used to synthesize ATP through substrate-level phosphorylation. 
D)  It is used to phosphorylate NAD⁺ to NADPH. 
A)  It excites electrons of the reaction center in photosystem I. 
B)  It is used to establish and maintain a proton gradient. 
C)  It is used to synthesize ATP through substrate-level phosphorylation. 
D)  It is used to phosphorylate NAD⁺ to NADPH.

Question 14

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

Accepted Answer

A)  All plants would have faster growth rates. 
B)  C₃ plants would have faster growth rates; C₄ plants would be minimally affected. 
C)  C₄ plants would have faster growth rates; C₃ plants would be minimally affected. 
D)  C₃ plants would have faster growth rates; C₄ plants would have slower growth rates. 
A)  All plants would have faster growth rates. 
B)  C₃ plants would have faster growth rates; C₄ plants would be minimally affected. 
C)  C₄ plants would have faster growth rates; C₃ plants would be minimally affected. 
D)  C₃ plants would have faster growth rates; C₄ plants would have slower growth rates.

Question 15

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

Accepted Answer

A)  Autotrophs, but not heterotrophs, can nourish themselves beginning with CO₂ and other nutrients that are inorganic. 
B)  Only heterotrophs require chemical compounds from the environment. 
C)  Cellular respiration is unique to heterotrophs. 
D)  Only heterotrophs have mitochondria. 
A)  Autotrophs, but not heterotrophs, can nourish themselves beginning with CO₂ and other nutrients that are inorganic. 
B)  Only heterotrophs require chemical compounds from the environment. 
C)  Cellular respiration is unique to heterotrophs. 
D)  Only heterotrophs have mitochondria.

Question 16

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?

Accepted Answer

A)  Bacteria congregated in these areas due to an increase in the temperature of the red and blue light. 
B)  Bacteria congregated in these areas because these areas had the most oxygen being released. 
C)  Bacteria are attracted to red and blue light and thus these wavelengths are more reactive than other wavelengths. 
D)  Bacteria congregated in these areas due to an increase in the temperature caused by an increase in photosynthesis. 
A)  Bacteria congregated in these areas due to an increase in the temperature of the red and blue light. 
B)  Bacteria congregated in these areas because these areas had the most oxygen being released. 
C)  Bacteria are attracted to red and blue light and thus these wavelengths are more reactive than other wavelengths. 
D)  Bacteria congregated in these areas due to an increase in the temperature caused by an increase in photosynthesis.

Question 17

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?

Accepted Answer

A)  splitting of water 
B)  flow of electrons from photosystem II to photosystem I 
C)  synthesis of ATP 
D)  reduction of NADP⁺ 
A)  splitting of water 
B)  flow of electrons from photosystem II to photosystem I 
C)  synthesis of ATP 
D)  reduction of NADP⁺

Question 18

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 ________.

Accepted Answer

A)  matrix to the stroma 
B)  stroma to the thylakoid space 
C)  thylakoid space to the matrix 
D)  thylakoid space to the stroma 
A)  matrix to the stroma 
B)  stroma to the thylakoid space 
C)  thylakoid space to the matrix 
D)  thylakoid space to the stroma

Question 19

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

Accepted Answer

A)  ATP 
B)  NADH 
C)  NADP⁺ 
D)  NADPH 
A)  ATP 
B)  NADH 
C)  NADP⁺ 
D)  NADPH

Question 20

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

Accepted Answer

A)  ATP is synthesized from the energy absorbed. 
B)  An electron is excited. 
C)  NADP⁺ is reduced to NADPH. 
D)  A molecule of water is split. 
A)  ATP is synthesized from the energy absorbed. 
B)  An electron is excited. 
C)  NADP⁺ is reduced to NADPH. 
D)  A molecule of water is split.

Exam 10: Photosynthesis

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

In mechanism, photophosphorylation is most similar to

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

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

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

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

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?

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

Compared to C₃ plants, C₄ plants ________.

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

How is photosynthesis similar in C₄ plants and CAM plants?

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

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

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

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?

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 ________.

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

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

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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