Chapter 10

Question 1

If photosynthesizing green algae are provided with CO₂ synthesized with heavy oxygen (¹⁸O), later analysis will show that all but one of the following compounds produced by the algae contain the ¹⁸O label. That one is 
A) 3-phosphoglycerate. 
B) glyceraldehyde 3-phosphate (G3P). 
C) glucose. 
D) ribulose bisphosphate (RuBP). 
E) O₂.

Answer 1

O2

Question 2

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle? 
A) CO₂ and glucose 
B) H₂O and O₂ 
C) ADP, Pi, and NADP⁺ 
D) electrons and H⁺ 
E) ATP and NADPH

Answer 2

ATP and NADPH

Question 3

Where does the Calvin cycle take place?
A) stroma of the chloroplast
B) thylakoid membrane
C) cytoplasm surrounding the chloroplast
D) interior of the thylakoid (thylakoid space)
E) outer membrane of the chloroplast

Answer 3

stroma of the chloroplast

Question 4

In autotrophic bacteria, where are the enzymes located that can carry on carbon fixation (reduction of carbon dioxide to carbohydrate)? 
A) in chloroplast membranes 
B) in chloroplast stroma 
C) in the cytosol 
D) in the nucleoid 
E) in the infolded plasma membrane

Answer 4

in the cytosol

Question 5

When oxygen is released as a result of photosynthesis, it is a direct by-product of
A) reducing NADP⁺.
B) splitting water molecules.
C) chemiosmosis.
D) the electron transfer system of photosystem I.
E) the electron transfer system of photosystem II.

Answer 5

splitting water molecules.

Question 6

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment? 
A) red and yellow 
B) blue and violet 
C) green and yellow 
D) blue, green, and red 
E) green, blue, and yellow

Answer 6

blue and violet

Question 7

Halobacterium has a photosynthetic membrane that is colored purple. Its photosynthetic action spectrum is exactly complementary (opposite to) the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb? 
A) red and yellow 
B) blue, green, and red 
C) green and yellow 
D) red and green 
E) blue and red

Answer 7

blue and red

Question 8

In the thylakoid membranes, what is the main role of the antenna pigment molecules?
A) split water and release oxygen to the reaction-center chlorophyll
B) harvest photons and transfer light energy to the reaction-center chlorophyll
C) synthesize ATP from ADP and Pi
D) transfer electrons to ferredoxin and then NADPH
E) concentrate photons within the stroma

Answer 8

harvest photons and transfer light energy to the reaction-center

Question 9

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

Answer 9

Light is absorbed and funneled to reaction-center chlorophyll a.

Question 10

Which statement describes the functioning of photosystem II?
A) Light energy excites electrons in the thylakoid membrane electron transport chain.
B) Photons are passed along to a reaction-center chlorophyll.
C) The P680 chlorophyll donates a pair of protons to NADP⁺, which is thus converted to NADPH.
D) The electron vacancies in P680⁺ are filled by electrons derived from water.
E) The splitting of water yields molecular carbon dioxide as a by-product.

Answer 10

The electron vacancies in P680⁺ are filled by electrons derived from water

Question 11

Which of the following are directly associated with photosystem I?
A) harvesting of light energy by ATP
B) receiving electrons from the thylakoid membrane electron transport chain
C) generation of molecular oxygen
D) extraction of hydrogen electrons from the splitting of water
E) passing electrons to the thylakoid membrane electron transport chain

Answer 11

receiving electrons from the thylakoid membrane electron transport chain

Question 12

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be
A) to determine if they have thylakoids in the chloroplasts.
B) to test for liberation of O₂ in the light.
C) to test for CO₂ fixation in the dark.
D) to do experiments to generate an action spectrum.
E) to test for production of either sucrose or starch.

Answer 12

to test for liberation of O₂ in the light.

Question 13

What are the products of linear photophosphorylation? 
A) heat and fluorescence 
B) ATP and P700 
C) ATP and NADPH 
D) ADP and NADP 
E) P700 and P680

Answer 13

ATP and NADPH

Question 14

As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find 30,000 molecules of ATP consumed, but only 20,000 molecules of NADPH. Where did the extra ATP molecules come from? 
A) photosystem II 
B) photosystem I 
C) cyclic electron flow 
D) linear electron flow 
E) chlorophyll

Answer 14

cyclic electron flow

Question 15

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
A) the splitting of water
B) the absorption of light energy by chlorophyll
C) the flow of electrons from photosystem II to photosystem I
D) the synthesis of ATP
E) the reduction of NADP⁺

Answer 15

the synthesis of ATP

Question 16

What does the chemiosmotic process in chloroplasts involve?
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 energy
D) movement of water by osmosis into the thylakoid space from the stroma
E) formation of glucose, using carbon dioxide, NADPH, and ATP

Answer 16

establishment of a proton gradient across the thylakoid membrane

Question 17

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH 8 solution. What would be likely to happen?
A) The isolated chloroplasts will make ATP.
B) The Calvin cycle will be activated.
C) Cyclic photophosphorylation will occur.
D) The isolated chloroplasts will generate oxygen gas.
E) The isolated chloroplasts will reduce NADP⁺ to NADPH.

Answer 17

The isolated chloroplasts will make ATP.

Question 18

In a plant cell, where are the ATP synthase complexes located?
A) thylakoid membrane only
B) plasma membrane only
C) inner mitochondrial membrane only
D) thylakoid membrane and inner mitochondrial membrane
E) thylakoid membrane and plasma membrane

Answer 18

thylakoid membrane and inner mitochondrial membrane

Question 19

In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
A) the stroma to the photosystem II.
B) the matrix to the stroma.
C) the stroma to the thylakoid space.
D) the intermembrane space to the matrix.
E) the thylakoid space to the stroma.

Answer 19

the stroma to the thylakoid space.

Question 20

Which of the following statements best describes the relationship between photosynthesis and respiration?
A) Respiration runs the biochemical pathways of photosynthesis in reverse.
B) Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.
C) Photosynthesis occurs only in plants and respiration occurs only in animals.
D) ATP molecules are produced in photosynthesis and used up in respiration.
E) Respiration is anabolic and photosynthesis is catabolic.

Answer 20

Photosynthesis stores energy in complex organic molecules, whereas respiration releases it.

Question 21

Where are the molecules of the electron transport chain found in plant cells? 
A) thylakoid membranes of chloroplasts 
B) stroma of chloroplasts 
C) outer membrane of mitochondria 
D) matrix of mitochondria 
E) cytoplasm

Answer 21

thylakoid membranes of chloroplasts

Question 22

In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during
A) photosynthesis only.
B) respiration only.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration only.

Answer 22

both photosynthesis and respiration.

Question 23

Reduction of NADP⁺ occurs during 
A) photosynthesis. 
B) respiration. 
C) both photosynthesis and respiration. 
D) neither photosynthesis nor respiration. 
E) photorespiration.

Answer 23

photosynthesis.

Question 24

The splitting of carbon dioxide to form oxygen gas and carbon compounds occurs during
A) photosynthesis.
B) respiration.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration.

Answer 24

neither photosynthesis nor respiration.

Question 25

Generation of proton gradients across membranes occurs during
A) photosynthesis.
B) respiration.
C) both photosynthesis and respiration.
D) neither photosynthesis nor respiration.
E) photorespiration.

Answer 25

both photosynthesis and respiration.

Question 26

What is the relationship between wavelength of light and the quantity of energy per photon?
A) They have a direct, linear relationship.
B) They are inversely related.
C) They are logarithmically related.
D) They are separate phenomena.
E) They are only related in certain parts of the spectrum.

Answer 26

They are inversely related

Question 27

P680⁺ is said to be the strongest biological oxidizing agent. Why?
A) It is the receptor for the most excited electron in either photosystem.
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) This molecule has a stronger attraction for electrons than oxygen, to obtain electrons from water.
E) It has a positive charge.

Answer 27

This molecule has a stronger attraction for electrons than oxygen, to obtain electrons from water.

Question 28

Some photosynthetic bacteria (e.g., purple sulfur bacteria) have only photosystem I, whereas others (e.g., cyanobacteria) have both photosystem I and photosystem II. Which of the following might this observation imply?
A) Photosystem II was selected against in some species.
B) Photosynthesis with only photosystem I is more ancestral.
C) Photosystem II may have evolved to be more photoprotective.
D) Linear electron flow is more primitive than cyclic flow of electrons.
E) Cyclic flow is more necessary than linear electron flow.

Answer 28

Photosynthesis with only photosystem I is more ancestral.

Question 29

electron flow may be photoprotective (protective to light-induced damage). Which of the following experiments could provide information on this phenomenon?
A) use mutated organisms that can grow but that cannot carry out cyclic flow of electrons and compare their abilities to photosynthesize in different light intensities against those of wild-type organisms
B) use plants that can carry out both linear and cyclic electron flow, or only one or another of these processes, and compare their light absorbance at different wavelengths and different light intensities
C) use bacteria that have only cyclic flow and look for their frequency of mutation damage at different light intensities
D) use bacteria with only cyclic flow and measure the number and types of photosynthetic pigments they have in their membranes
E) use plants with only photosystem I operative and measure how much damage occurs at different wavelengths

Answer 29

use mutated organisms that can grow but that cannot carry out cyclic flow of electrons and compare their abilities to photosynthesize in different light intensities against those of wild-type organisms

Question 30

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

Answer 30

They protect against oxidative damage from excessive light energy

Question 31

In thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. Therefore, the catalytic “knobs” of ATP synthase would be located
A) on the side facing the thylakoid space.
B) on the ATP molecules themselves.
C) on the pigment molecules of photosystem I and photosystem II.
D) on the stromal side of the membrane.
E) built into the center of the thylakoid stack (granum).

Answer 31

on the stromal side of the membrane.

Question 32

In metabolic processes of cell respiration and photosynthesis, prosthetic groups such as heme and iron-sulfur complexes are encountered in components of the electron transport chain. What do they do?
A) donate electrons
B) act as reducing agents
C) act as oxidizing agents
D) transport protons within the mitochondria and chloroplasts
E) both oxidize and reduce during electron transport

Answer 32

both oxidize and reduce during electron transport

Question 33

In a cyanobacterium, the reactions that produce NADPH occur in
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 is not part of photosynthesis.

Answer 33

the light reactions alone.

Question 34

Where do the enzymatic reactions of the Calvin cycle take place? 
A) stroma of the chloroplast 
B) thylakoid membranes 
C) matrix of the mitochondria 
D) cytosol around the chloroplast 
E) thylakoid space

Answer 34

stroma of the chloroplast

Question 35

What is the primary function of the Calvin cycle?
A) use ATP to release carbon dioxide
B) use NADPH to release carbon dioxide
C) split water and release oxygen
D) transport RuBP out of the chloroplast
E) synthesize simple sugars from carbon dioxide

Answer 35

synthesize simple sugars from carbon dioxide

Question 36

In C₃ photosynthesis, the reactions that require ATP take place in
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 is not part of photosynthesis.

Answer 36

the Calvin cycle alone.

Question 37

In a plant leaf, the reactions that produce NADH occur in
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 is not part of photosynthesis.

Answer 37

neither the light reactions nor the Calvin cycle.

Question 38

The NADPH required for the Calvin cycle comes from
A) reactions initiated in photosystem I.
B) reactions initiated in photosystem II.
C) the citric acid cycle.
D) glycolysis.
E) oxidative phosphorylation.

Answer 38

reactions initiated in photosystem I.

Question 39

Reactions that require CO₂ take place in
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 is not part of photosynthesis.

Answer 39

the Calvin cycle alone.

Question 40

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
A) The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, 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.

Answer 40

The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP⁺ to the light reactions.

Question 41

Three “turns” of the Calvin cycle generate a “surplus” molecule of glyceraldehyde 3-phosphate (G3P). Which of the following is a consequence of this?
A) Formation of a molecule of glucose would require nine “turns.”
B) G3P more readily forms sucrose and other disaccharides than it does monosaccharides.
C) Some plants would not taste sweet to us.
D) The formation of sucrose and starch in plants involves assembling G3P molecules, with or without further rearrangements.
E) Plants accumulate and store G3P.

Answer 41

The formation of sucrose and starch in plants involves assembling G3P molecules, with or without further rearrangements

Question 42

In the process of carbon fixation, RuBP attaches a CO₂ to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle?
A) addition of a pair of electrons from NADPH
B) inactivation of RuBP carboxylase enzyme
C) regeneration of ATP from ADP
D) regeneration of RuBP
E) regeneration of NADP⁺

Answer 42

regeneration of RuBP

Question 43

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?
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 that anywhere else in the cell.
E) There is no consistent relationship

Answer 43

The pH within the thylakoid is less than that of the stroma

Question 44

The phylogenetic distribution of the enzyme rubisco is limited to
A) C₃ plants only.
B) C₃ and C₄ plants.
C) all photosynthetic eukaryotes.
D) all known photoautotrophs, both bacterial and eukaryotic.
E) all living cells.

Answer 44

all known photoautotrophs, both bacterial and eukaryotic.

Question 45

Photorespiration occurs when rubisco reacts RuBP with 
A) CO₂. 
B) O₂. 
C) glyceraldehyde 3-phosphate. 
D) 3-phosphoglycerate. 
E) NADPH.

Answer 45

O₂

Question 46

In an experiment studying photosynthesis performed during the day, you provide a plant with radioactive carbon (¹⁴C) dioxide as a metabolic tracer. The ¹⁴C is incorporated first into oxaloacetate. The plant is best characterized as a 
A) C₄ plant. 
B) C₃ plant. 
C) CAM plant. 
D) heterotroph. 
E) chemoautotroph

Answer 46

C₄ plant

Question 47

Why are C₄ plants able to photosynthesize with no apparent photorespiration?
A) They do not participate in the Calvin cycle.
B) They use PEP carboxylase to initially fix CO₂.
C) They are adapted to cold, wet climates.
D) They conserve water more efficiently.
E) They exclude oxygen from their tissues.

Answer 47

They use PEP carboxylase to initially fix CO₂.

Question 48

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

Answer 48

fix CO₂ into organic acids during the night.

Question 49

Photorespiration lowers the efficiency of photosynthesis by 
A) carbon dioxide molecules. 
B) 3-phosphoglycerate molecules. 
C) ATP molecules. 
D) ribulose bisphosphate molecules. 
E) RuBP carboxylase molecules.

Answer 49

3-phosphoglycerate molecules.

Question 50

The alternative pathways of photosynthesis using the C₄ or CAM systems are said to be compromises. Why?
A) Each one minimizes both water loss and rate of photosynthesis.
B) C₄ compromises on water loss and CAM compromises on photorespiration.
C) Both minimize photorespiration but expend more ATP during carbon fixation.
D) CAM plants allow more water loss, while C₄ plants allow less CO₂ into the plant.
E) C₄ plants allow less water loss but CAM plants allow more water loss.

Answer 50

Both minimize photorespiration but expend more ATP during carbon fixation

Question 51

If plant gene alterations cause the plants to be deficient in photorespiration, what would most probably occur?
A) Photosynthetic efficiency would be reduced at low light intensities.
B) Cells would carry on the Calvin cycle at a much slower rate.
C) Less ATP would be generated.
D) There would be more light-induced damage to the cells.
E) Less oxygen would be produced

Answer 51

There would be more light-induced damage to the cells.

Question 52

Compared to C₃ plants, C₄ plants
A) can continue to fix CO₂ even at relatively low CO2 concentrations and high oxygen concentrations.
B) have higher rates of photorespiration.
C) do not use rubisco for carbon fixation.
D) grow better under cool, moist conditions.
E) make a four-carbon compound, oxaloacetate, which is then delivered to the citric acid cycle in mitochondria.

Answer 52

can continue to fix CO₂ even at relatively low CO2 concentrations and high oxygen concentrations.

Question 53

If atmospheric CO₂ concentrations increase twofold or more, how will plants be affected, disregarding any changes in climate?
A) All plants will experience increased rates of photosynthesis
B) C₃ plants will have faster growth; C₄ plants will be minimally affected.
C) C₄ plants will have faster growth; C₃ plants will be minimally affected.
D) C₃ plants will have faster growth; C₄ plants will have slower growth
E) Plant growth will not be affected because atmospheric CO₂ concentrations are never limiting for plant growth

Answer 53

C₃ plants will have faster growth; C₄ plants will be minimally affected.

Question 54

Plants photosynthesize only in the light. Plants respire
A) in the dark only.
B) in the light only.
C) both in light and dark.
D) never–they get their ATP from photophosphorylation.
E) only when excessive light energy induces photorespiration.

Answer 54

both in light and dark

Question 55

Figure 10.1 shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
A) Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.
B) Bright sunlight destroys photosynthetic pigments.
C) Oxygen given off during photosynthesis interferes with the absorption of light.
D) Other pigments absorb light in addition to chlorophyll a.
E) Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.

Answer 55

Other pigments absorb light in addition to chlorophyll a.

Question 56

What wavelength of light in the figure is most effective in driving photosynthesis? 
A) 420 mm 
B) 475 mm 
C) 575 mm 
D) 625 mm 
E) 730 mm

Answer 56

420 mm

Question 57

If ATP used by this plant is labeled with radioactive phosphorus, which molecule or molecules of the Calvin cycle will be radioactively labeled first? 
A) B only 
B) B and C only 
C) B, C, and D only 
D) B and E only 
E) B, C, D, and E

Answer 57

B and E only

Question 58

If the carbon atom of the incoming CO₂ molecule is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle? 
A) C only 
B) B, C, D, and E 
C) C, D, and E only 
D) B and C only 
E) B and D only

Answer 58

B, C, D, and E

Question 59

Which molecule(s) of the Calvin cycle is (are) also found in glycolysis? 
A) B, C, E, and 3-phosphoglycerate 
B) B, C, and E only 
C) 3-phosphoglycerate only 
D) B, C, D, and 3-phosphoglycerate only 
E) E only

Answer 59

B, C, D, and 3-phosphoglycerate only

Question 60

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? Study Figure 10.2 to help you in determining the correct answer.
A) The CO₂ acceptor concentration would decrease when either the CO₂ or light are cut off.
B) The CO₂ acceptor concentration would increase when either the CO₂ or light are 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.

Answer 60

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

Question 61

Which of the following statements is true concerning Figure 10.3?
A) It represents cell processes involved in C₄ photosynthesis.
B) It represents the type of cell structures found in CAM plants.
C) It represents an adaptation that maximizes photorespiration.
D) It represents a C₃ photosynthetic system.
E) It represents a relationship between plant cells that photosynthesize and those that cannot.

Answer 61

It represents cell processes involved in C₄ photosynthesis.

Question 62

Referring to Figure 10.3, oxygen would inhibit the CO₂ fixation reactions in
A) cell I only.
B) cell II only.
C) neither cell I nor cell II.
D) both cell I and cell II.
E) cell I during the night and cell II during the day.

Answer 62

cell II only.

Question 63

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. What color should she use to reduce overall light energy, but still maximize plant growth? 
A) green 
B) blue 
C) yellow 
D) orange 
E) any color will work equally well

Answer 63

blue

Question 64

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

Answer 64

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

Question 65

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.

An outcome of this experiment was to help determine
A) the relationship between heterotrophic and autotrophic organisms.
B) the relationship between wavelengths of light and the rate of aerobic respiration.
C) the relationship between wavelengths of light and the amount of heat released.
D) the relationship between wavelengths of light and the rate of photosynthesis.
E) the relationship between the concentration of carbon dioxide and the rate of photosynthesis.

Answer 65

the relationship between wavelengths of light and the rate of photosynthesis.

Question 66

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.

If you ran the same experiment without passing light through a prism, what would you predict?
A) There would be no difference in results.
B) The bacteria would be relatively evenly distributed along the algal filaments.
C) The number of bacteria present would decrease due to an increase in the carbon dioxide concentration.
D) The number of bacteria present would increase due to an increase in the carbon dioxide concentration.
E) The number of bacteria would decrease due to a decrease in the temperature of the water.

Answer 66

The bacteria would be relatively evenly distributed along the algal filaments.

Question 67

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) full-spectrum white light 
B) green light 
C) a mixture of blue and red light 
D) yellow light 
E) UV light

Answer 67

a mixture of blue and red light

Question 68

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.

If the power fails and the lights go dark, what will happen to CO₂ levels?
A) CO₂ will rise as a result of both animal and plant respiration.
B) CO₂ will rise as a result of animal respiration only.
C) CO₂ will remain balanced because plants will continue to fix CO₂ in the dark.
D) CO₂ will fall because plants will increase CO₂ fixation.
E) CO₂ will fall because plants will cease to respire in the dark.

Answer 68

CO₂ will rise as a result of both animal and plant respiration.

Question 69

The light reactions of photosynthesis supply the Calvin cycle with 
A) light energy. 
B) CO₂ and ATP. 
C) H₂O and NADPH. 
D) ATP and NADPH. 
E) sugar and O₂.

Answer 69

ATP and NADPH.

Question 70

Which of the following sequences correctly represents the flow of electrons during photosynthesis? 
A) NADPH → O₂ → CO₂ 
B) H₂O → NADPH → Calvin cycle 
C) NADPH → chlorophyll → Calvin cycle 
D) H₂O → photosystem I → photosystem II 
E) NADPH → electron transport chain → O₂

Answer 70

H₂O → NADPH → Calvin cycle

Question 71

How is photosynthesis similar in C₄ plants and CAM plants?
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.
E) In both cases, thylakoids are not involved in photosynthesis.

Answer 71

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

Question 72

Which of the following statements is a correct distinction between autotrophs and heterotrophs?
A) Only heterotrophs require chemical compounds from the environment.
B) Cellular respiration is unique to heterotrophs.
C) Only heterotrophs have mitochondria.
D) Autotrophs, but not heterotrophs, can nourish themselves beginning with CO₂ and other nutrients that are inorganic.
E) Only heterotrophs require oxygen.

Answer 72

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

Question 73

Which of the following does not occur during the Calvin cycle? 
A) carbon fixation 
B) oxidation of NADPH 
C) release of oxygen 
D) regeneration of the CO₂ acceptor 
E) consumption of ATP

Answer 73

release of oxygen

Question 74

In mechanism, photophosphorylation is most similar to
A) substrate-level phosphorylation in glycolysis.
B) oxidative phosphorylation in cellular respiration.
C) the Calvin cycle.
D) carbon fixation.
E) reduction of NADP⁺.

Answer 74

oxidative phosphorylation in cellular respiration.

Question 75

Which process is most directly driven by light energy?
A) creation of a pH gradient by pumping protons across the thylakoid membrane
B) carbon fixation in the stroma
C) reduction of NADP⁺ molecules
D) removal of electrons from chlorophyll molecules
E) ATP synthesis

Answer 75

removal of electrons from chlorophyll molecules