Mastering Biology Chapter 7
What two molecules are produced by the light reactions and used to power the Calvin cycle? ATP and NADPH G3P and H2O C6H12O6 and O2 CO2 and O2 C6H12O6 and RuBP
ATP and NADH
Which of the following are produced during the light reactions of photosynthesis? glucose, ADP, NADP+, CO2 glucose, ADP, NADP+ ADP, NADP+, O2 ATP, NADPH, O2
ATP, NADPH, O2
What connects the two photosystems in the light reactions? A chain of glucose molecules A thylakoid The Calvin cycle An electron transport chain Chlorophyll
An electron transport chain
Why are most plants green? -Chlorophyll a absorbs green light. -Chlorophyll b primarily uses green light as the source of energy for photosynthesis. -Green helps plants blend into their environment as a sort of camouflage. -Chlorophyll a reflects green light.
Chlorophyll a reflects green light.
How do the reaction centers of photosystem I and II differ? - Photosystem I functions first in the sequence of steps that make up the light reactions. -Chlorophyll a is found in photosystem I and chlorophyll b in photosystem II. -Each preferentially absorbs slightly different wavelengths of light. -Photosystem II does not transfer electrons from photons.
Each preferentially absorbs slightly different wavelengths of light.
Which of the following statements about photosynthesis is true in regard to the reduction of CO2 to sugar? -Electrons (with accompanying protons) are removed from CO2 during photosynthesis and added to water molecules to form sugar. -Oxygen is removed from CO2 during photosynthesis. -Hydrogen is added to CO2 during photosynthesis. -Electrons (with accompanying protons) are added to CO2 during photosynthesis.
Electrons (with accompanying protons) are added to CO2 during photosynthesis.
As photosynthesis occurs in chloroplasts, O2 is produced from _____ via a series of reactions associated with _____. H2O ... photosystem II CO2 ... photosystem II CO2 ... Calvin cycle H2O ... photosystem I
H2O ... photosystem II
Which of the following statements concerning the role of redox reactions in photosynthesis and cellular respiration is true? -Photosynthesis involves only reductions, while respiration involves only oxidations. -In photosynthesis, carbon dioxide is reduced to form sugar, while in respiration, sugar is oxidized to form carbon dioxide. -In photosynthesis, carbon dioxide is oxidized to form sugar, while in respiration, sugar is reduced to form carbon dioxide. -Photosynthesis involves only oxidations, while respiration involves only reductions.
In photosynthesis, carbon dioxide is reduced to form sugar, while in respiration, sugar is oxidized to form carbon dioxide.
What is the role of NADP+ in photosynthesis? -It assists chlorophyll in capturing light. -It is part of the electron transport chain and is involved with the manufacture of ATP. -It acts as the primary electron acceptor for the photosystems. -It is reduced and then carries electrons to the Calvin cycle.
It is reduced and then carries electrons to the Calvin cycle.
Oxygen is the final electron acceptor for cellular respiration. What is the final electron acceptor in photosynthesis? ATP light NADP+ water
NADP+
As a result of the cascade of electrons down the electron transport chains of the light reactions, NADP+ is oxidized to NADPH. NADPH is reduced to NADP+. NADP+ is reduced to NADPH. NADPH is oxidized to NADP+.
NADP+ is reduced to NADPH.
What transports electrons from the light reactions to the Calvin cycle? FADH2 NADPH NADH Chlorophyll An electron transport chain
NADPH
The light reactions of photosynthesis generate high-energy electrons, which end up in _____. The light reactions also produce _____ and _____. chlorophyll ... ATP ... NADPH ATP ... NADPH ... oxygen oxygen ... sugar ... ATP NADPH ... ATP ... oxygen
NADPH ... ATP ... oxygen
Although the reactions of the Calvin cycle are not directly dependent on light, they usually do not occur at night. Why? -It is often too cold at night for these reactions to take place. -Carbon dioxide concentrations decrease at night. -Plants usually open their stomata at night. -The Calvin cycle depends on products of the light reactions.
The Calvin cycle depends on products of the light reactions.
In a photosystem, clusters of chlorophyll a, chlorophyll b, and carotenoid pigments function most like -a spring. -a propeller on a motorboat. -a windmill. -an antenna.
an antenna.
Calvin cycle in C4 plants takes place in the _____. mesophyll matrix bundle-sheath cells stroma
bundle-sheath cells
Photosynthetic organisms derive their carbon from carbon monoxide. carbon dioxide. hydrocarbons. methane.
carbon dioxide
Which of the following is an example of a photoautotroph? -cyanobacteria in freshwater and marine ecosystems -mushrooms growing on the side of a dead tree -bacteria in our mouth -grizzly bears in Alaska
cyanobacteria in freshwater and marine ecosystem
he full range of electromagnetic energy is called the ________ spectrum. energy visible ultraviolet electromagnetic
electromagnetic
Sunlight is a type of ________ energy. Check all that apply. potential electromagnetic nuclear kinetic
electromagnetic and kintetic
Which of the following is part of the light reaction? formation of waste products in the form of O2 regeneration of NADP+ carbon fixation reduction of carbon
formation of waste products in the form of O2
Which of the following are produced during the Calvin cycle? glucose, ADP, NADP+ ATP, NADPH, O2 ATP, NADPH, CO2 glucose, ADP, NADP+, CO2
glucose, ADP, NADP+
Chloroplasts contain disklike membranous sacs arranged in stacks called vacuoles. thylakoids. grana. cristae.
grana
Of the following wavelengths of light, which would you expect to be reflected or transmitted by chlorophyll a? red yellow green blue
green
Which of the following colors contributes the least energy to photosynthesis? green orange blue red
green
Which of the following colors is most strongly reflected by chlorophyll? green orange yellow red
green
The synthesis of glucose by photosynthesis is an endergonic process. The source of the energy for the excited electrons is _____. water chlorophyll carbon dioxide light
light
What is the source of energy that provides the boost for electrons during photosynthesis? electromagnetism light ATP cellular respiration
light
Molecular oxygen is produced during _____. aerobic respiration the Calvin cycle glycolysis light reactions of photosynthesis
light reactions of photosynthesis
________ cells in leaves are specialized for photosynthesis. Tracheid Companion Mesophyll Sclerenchyma
mesophyll
In addition to its function in mitochondria, the chemiosmotic mechanism is important for generating ATP during the _____. synaptic transmission photoexcitation of electrons process of intracellular digestion within lysosomes fermentation of glucose
photoexcitation of electrons
A packet of light energy is called a quantum. phaser. photon. pigmen
photon
The energy that excites P680 and P700 is supplied by NADPH. electrons passing down the electron transport chain. ATP. photons.
photons
The light reactions of photosynthesis include _____. the stoma the Calvin cycle reduction of NADP+ reduction of CO2 NADPH recycling
reduction of NADP+
The electron transport chains of the light reactions are located in the stroma. shuttle electrons along in a series of redox reactions. provide energy for the citric acid cycle. are found on the plasma membrane of mesophyll cells.
shuttle electrons along in a series of redox reactions.
CO2 enters and O2 escapes from a leaf via stomata. grana. thylakoids. stroma.
stomata
In the chloroplast, sugars are made in a compartment that is filled with a thick fluid called the stroma. stomata. matrix. thylakoid.
stroma
The electrons lost from the reaction center of photosystem I are replaced by electrons from -the bottom of the electron transport chain. -the top of the electron transport chain. -H2O. -CO2.
the bottom of the electron transport chain.
Photophosphorylation during photosynthesis differs from oxidative phosphorylation during cellular respiration in that regeneration of ATP is driven by a flow of protons through an ATP synthase. energy is stored in the form of a proton concentration difference. the final electron acceptor is NADP+ and not oxygen. it involves an electron transport chain.
the final electron acceptor is NADP+ and not oxygen.
When chloroplast pigments absorb light, _____. they become reduced they lose potential energy the Calvin cycle is triggered their electrons become excited
their electrons become excited
Chlorophyll is found in the _____ of chloroplasts. thylakoid membranes outer membrane stroma thylakoid space
thylakoid membranes
Where is chlorophyll found in a plant cell? stroma cristae thylakoid membranes cytoplasm
thylakoid membranes
The light reactions occur in the ________, while the Calvin cycle occurs in the ________. stroma . . . nucleus thylakoid membranes . . . stroma stroma . . . thylakoid membranes cytoplasm . . . thylakoid membrane
thylakoid membranes . . . stroma
The light reactions take place in the _________ and the Calvin cycle takes place in the _________. thylakoids; stroma stroma; thylakoids inner membrane; outer membrane chloroplasts; mitochondria mitochondria; chloroplasts
thylakoids; stroma
During photosynthesis, an electron transport chain is used to _____. -transport NADPH from the light reactions to the Calvin cycle -transport electrons from photosystem II to photosystem I -transport excited electrons from P680 to an electron acceptor -transport excited electrons from P700 to an electron acceptor
transport electrons from photosystem II to photosystem I
Both mitochondria and chloroplasts _____. use an H+ gradient to produce ATP obtain electrons from water reduce NAD+, forming NADP release oxygen as a by-product
use an H+ gradient to produce ATP
The oxygen released into the air as a product of photosynthesis comes from glucose. water. chlorophyll. carbon dioxide.
water
here do the electrons needed by photosystem II originate? ATP other chlorophyll molecules water the electron transport chain
water
Which of the following equations represents photosynthesis? 6CO2 + 6O2 → C6H12O6 + 6H2O 6CO2 + 6H2O → C6H12O6 + 6O2 C6H12O6 + 6O2 → 6CO2 + 6H2O C6H12O6 + 6CO2 → 6O2 + 6H2O 6H2O + 6O2 → C6H12O6 + 6CO2
6CO2 + 6H2O → C6H12O6 + 6O2
Which of the following statements regarding photosynthesis is false? -ATP is not produced during photosynthesis, but only during cellular respiration. -Photosynthesis produces O2; respiration produces CO2. -Photosynthesis consumes CO2; respiration consumes O2. -Photosynthesis is ultimately powered by light energy and respiration by the chemical energy of fuel molecules.
ATP is not produced during photosynthesis, but only during cellular respiration.
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle? G3P (C3H6O3) Glucose (C6H12O6) Sucrose (C12H22O11) Carbon dioxide (CO2) RuBP
Carbon dioxide (CO2)
Which statement regarding the light reactions is true? -Photoexcited electrons pass from photosystem I to photosystem II. -Glucose is a product of the light reactions. -Electrons are supplied to chlorophyll P680 as it reduces the primary electron acceptor. -ATP synthesis occurs as electrons "fall" down the electron transport chain.
Electrons are supplied to chlorophyll P680 as it reduces the primary electron acceptor.
The final output of the Calvin cycle is _____. ATP 3-PGA G3P RuBP
G3P
If you expose a photosynthesizing plant to water that contains both radioactive H and radioactive O, in which of the products of photosynthesis will the radioactive H and O show up? H in water; O in glucose H and O both in glucose H in glucose; O in water H in glucose and water; O in O2
H in glucose and water; O in O2
In photophosphorylation, energy from electron flow is used to transport ________ from the ________ to the thylakoid compartment, generating a concentration gradient of ________. electrons . . . grana . . . H+ H+ . . . stroma . . . ATP H+ . . . grana . . . electrons H+ . . . stroma . . . H+
H+ . . . stroma . . . H+
The electrons lost from the reaction center of photosystem II are replaced by electrons from ATP. CO2. H2O. photosystem I.
H20
What provides electrons for the light reactions? H2O The Calvin cycle Light O2 CO2
H2O
Which of the following molecules is both a reactant and a product of photosynthesis? chlorophyll H2O O2 glucose
H2O
The impact of a sufficiently large asteroid or comet is one of the theories that have been put forward to explain why dinosaurs became extinct. Why would this extinction-level event have such a major impact? -It produced dust and other particulates that would block out the sun. -The toxic fumes produced meant that the dinosaurs could no longer breathe. -It created enormous tidal waves and huge forest fires. -It increased the temperature of the planet.
It produced dust and other particulates that would block out the sun.
Hydrogen is a leading candidate in the search for a petroleum replacement. However, the hydrogen-generating reaction requires more energy than it produces. Why are plants considered to be one step ahead in the utilization of hydrogen as an alternative fuel source? -Plant cells possess water-splitting enzymes. -Plant cells break down carbohydrates to generate hydrogen. -Plant cells harness the ATP produced during photosynthesis to split water. -Plant cells convert carbon to combustible hydrogen.
Plant cells possess water-splitting enzymes.
Which of the following statements about the absorption of photons by pigment molecules is true? -Photons raise electrons in pigments to the ground state. -The release of energy by the excited electron can be as heat, light, or fluorescence. -Excitation of the electrons is a very stable state. -It takes several minutes for the pigment electrons to become excited.
The release of energy by the excited electron can be as heat, light, or fluorescence.
A red chemical dye known as phenol red changes to yellow when CO2 is present. A small green plant seedling is placed in phenol red and then placed in the dark. Which of the following is most likely to occur? -The solution is red to begin with, and it will turn yellow because respiration is occurring. -The solution is red to begin with, and it will turn yellow because photosynthesis is occurring. -The solution is yellow to begin with, and it will turn red because respiration is occurring. -The solution is yellow to begin with, and it will turn red because photosynthesis is occurring.
The solution is red to begin with, and it will turn yellow because respiration is occurring.
You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. What has the plant been using for an energy source while in the dark? -While it did have access to light before you left, the plant stored energy in the form of sugars or starch, and it was able to derive energy from those during your vacation. -Even though it cannot carry out the light reactions, the plant can still produce sugars because the Calvin cycle does not require light. -Even though the plant received no visible light, it was able to use the shortwave part of the electromagnetic spectrum (gamma rays and X-rays) to carry out photosynthesis. -When light energy is not available, plants can derive energy from inorganic molecules.
While it did have access to light before you left, the plant stored energy in the form of sugars or starch, and it was able to derive energy from those during your vacation.
The primary function of light absorption by photosystems I and II is to produce _____. -heat -a free, energized electron -oxygen -fluorescence
a free, energized electron
You're conducting an experiment to determine the effect of different wavelengths of light on the absorption of carbon dioxide as an indicator of the rate of photosynthesis in aquatic ecosystems. If the rate of photosynthesis increases, the amount of carbon dioxide in the environment will decrease and vice versa. You've added an indicator to each solution. When the carbon dioxide concentration decreases, the color of the indicator solution also changes. Small aquatic plants are placed into three containers of water mixed with carbon dioxide and indicator solution. Container A is placed under normal sunlight, B under green light, and C under red light. The containers are observed for a 24-hour period. Based on your knowledge of the process of photosynthesis, the plant in the container placed under red light would probably After reading the paragraph, answer the question(s) that follow. You're conducting an experiment to determine the effect of different wavelengths of light on the absorption of carbon dioxide as an indicator of the rate of photosynthesis in aquatic ecosystems. If the rate of photosynthesis increases, the amount of carbon dioxide in the environment will decrease and vice versa. You've added an indicator to each solution. When the carbon dioxide concentration decreases, the color of the indicator solution also changes. Small aquatic plants are placed into three containers of water mixed with carbon dioxide and indicator solution. Container A is placed under normal sunlight, B under green light, and C under red light. The containers are observed for a 24-hour period. Based on your knowledge of the process of photosynthesis, the plant in the container placed under red light would probably -absorb no CO2. -absorb more CO2 than the plants under the green light. -absorb the same amount of CO2 as the plants under both the green light and normal sunlight. -absorb less CO2 than the plants under green light.
absorb more CO2 than the plants under the green light.
A redox reaction involves the transfer of water. carbon dioxide. oxygen. an electron.
an electron
Which of the following may happen as a result of ozone depletion? a gradual rise in sea levels an increase in the number of individuals with skin cancer a shift in the location of deserts such as the Sahara a change in the planet's climate
an increase in the number of individuals with skin cancer
The Calvin cycle is a series of reactions that _____. assemble sugar molecules by fixing carbon convert light energy to chemical energy produce oxygen gas produce NADPH and ATP
assemble sugar molecules by fixing carbon
What is the name given to organisms that can make their own food and thus sustain themselves without consuming organic molecules derived from other organisms? heterotrophs chemotrophs autotrophs synthesizers
autotrophs
Which of the following colors of light are useful during the process of photosynthesis? blue, red, and violet green, orange, and red orange, red, and violet blue, green, and orange
blue, red, and violet
Considering the wavelengths of light shown below, the pigments in the granum absorb mainly in which range? blue-violet and red-orange green, which is why plants are green the entire spectrum of white light the infrared
blue-violet and red-orange
The most important role of pigments in photosynthesis is to _____. store energy in glucose molecules release energy from glucose molecules screen out harmful ultraviolet rays capture light energy
capture light energy
In the Calvin cycle carbon dioxide provides _____, whereas ATP and NADPH provide _____ and _____, respectively. high-energy electrons ... energy ... carbon energy ... carbon ...high-energy electrons carbon ... energy ... high-energy electrons hydrogen ... carbon ... energy
carbon ... energy ... high-energy electrons
Plant cells are protected from the harmful effects of reactive oxidative molecules by mitochondria. ATP. carotenoids. chlorophyll.
carotenoids
Mitochondria transfer ________ energy from ________ to ATP; chloroplasts transform ________ energy into the chemical energy of ATP. food . . . light . . . nuclear chemical . . . food . . . light light . . . food . . . kinetic food . . . light . . . chemical
chemical . . . food . . . light
Light reactions are located in the thylakoid membrane because _____. -the membrane brings chlorophyll closer to the light -the enzymes involved require a lipid bound to their active site -chemiosmosis can occur across the thylakoid membrane -the membrane functions as a mitochondrial membrane but at night
chemiosmosis can occur across the thylakoid membrane
Which of the following is a synthetic greenhouse gas? ozone chlorofluorocarbon carbon dioxide methane
chlorofluorocarbon
Which of the following photosynthetic pigments can be found at the photosystem reaction center? a carotenoid phycocyanin chlorophyll b chlorophyll a
chlorophyll a
In most green plants, chloroplasts are -concentrated in a portion of the leaf called the stroma. -evenly distributed throughout the leaf tissue. -concentrated in a zone of leaf tissue called the mesophyll. -evenly distributed throughout the entire plant.
concentrated in a zone of leaf tissue called the mesophyll.
Which of the following are photoautotrophs? -filamentous molds growing on bread -deep-sea vent organisms that make organic molecules using hydrogen sulfide as an energy source -bacteria found in the human digestive tract -corn stalks just before harvest
corn stalks just before harvest
The chloroplast ATP synthase helps transport H+ against the concentration gradient. couples the flow of H+ to the phosphorylation of ADP. is a nucleic acid complex. is found in the stroma.
couples the flow of H+ to the phosphorylation of ADP.
Which of the following is a normal process of photosynthesis that could not occur if all reaction centers were inactivated by a toxin? -donation of excited electrons by chlorophyll a to a primary electron acceptor -donation of excited electrons by chlorophyll b to a primary electron acceptor -absorption of photons by chlorophyll b -absorption of photons by carotenoids
donation of excited electrons by chlorophyll a to a primary electron acceptor
The conversion of NADP+ to NADPH occurs with the assistance of _____. -electrons from carbon dioxide and energy from ATP -electrons from water and energy from ATP -electrons from carbon dioxide and energy from sunlight -electrons from water and energy from sunlight
electrons from water and energy from sunlight
In an _____ process, photosynthesis _____ carbon, whereas cellular respiration is an _____ process that _____ carbon. endergonic ... oxidizes ... endergonic ... reduces exergonic ... reduces ... endergonic ... oxidizes endergonic ... oxidizes ... exergonic ... reduces endergonic ... reduces ... exergonic ... oxidizes
endergonic ... reduces ... exergonic ... oxidizes
Rubisco is the _____. -enzyme responsible for splitting H2O to produce O2 in photosynthesis -enzyme in C3 plants that first captures CO2 to begin the Calvin cycle -first stable intermediate in CAM metabolism -enzyme that forms a four-carbon compound in CAM metabolism
enzyme in C3 plants that first captures CO2 to begin the Calvin cycle
C4 plants have evolved different photosynthetic mechanisms. These plants _____. -do not fix CO2 through the Calvin cycle -fix CO2 into a four-carbon compound instead of a three-carbon compound -conserve water more efficiently by shutting their stomata during the day -are adapted to living in cold, wet climates where there is no water shortage
fix CO2 into a four-carbon compound instead of a three-carbon compound
NADP+ is required for photosynthesis because it _____. helps produce ATP from the light reactions forms NADPH to be used in the Calvin cycle absorbs light energy forms part of photosystem II
forms NADPH to be used in the Calvin cycle
C4 and CAM plants have adapted to living in environments where water loss is a problem. C4 plants fix carbon dioxide _____, whereas CAM plants fix carbon at _____. -at different times of the day ... different seasons -during different seasons ... different locations -in different locations ... different times of the day -at different times of the day ... different locations within the leaf
in different locations ... different times of the day
Solar radiation warms the surface of the planet and then is radiated back in the form of _____. UV radiation CO2 ozone infrared light
infrared light
In photosynthesis, the chemiosmotic production of ATP requires oxygen. is done by the Calvin cycle. is analogous to the production of ATP in mitochondria. is a result of the oxidation of glucose.
is analogous to the production of ATP in mitochondria.
The energy used to produce ATP in the light reactions of photosynthesis comes from _____. carbon fixation movement of H+ through a membrane splitting water the burning of sugar molecules
movement of H+ through a membrane
Carbon fixation -occurs when carbon atoms from CO2 are incorporated into an organic molecule. -occurs during the light reactions. -provides the cell with a supply of NADPH molecules. -supplies the cell with ATP.
occurs when carbon atoms from CO2 are incorporated into an organic molecule.
Clusters of light-gathering pigments in a photosystem -break down H2O. -are found in the roots of plants. -absorb electrons. -pass energy to the reaction center.
pass energy to the reaction center.
Chlorophyll b -is best at absorbing the energy of blue-violet and red light, just like chlorophyll a. -passes absorbed energy to chlorophyll a. -is best at absorbing the energy of green light. -catalyze the incorporation of carbon atoms into RuBP.
passes absorbed energy to chlorophyll a.
Photosystem II -does not have a reaction center. -passes electrons to photosystem I. -releases CO2 as a by-product. -has P700 at its reaction center.
passes electrons to photosystem I.
Autotrophs that utilize light as their energy source are photoautotrophs. chemosynthetic autotrophs. fungi. heterotrophs.
photoautotrophs
What is the likely origin of chloroplasts? -eukaryotes that engulfed photosynthetic fungi -photosynthetic prokaryotes that lived inside eukaryotic cells -mitochondria that had a mutation for photosynthesis -prokaryotes with photosynthetic mitochondria
photosynthetic prokaryotes that lived inside eukaryotic cells
The reaction center, antenna molecules, and primary electron acceptors that cluster in the thylakoid membrane form which structure? fluorescence center carbon-fixation unit electron transport chain photosystem
photosystem
ATP and NADPH are products of the Calvin cycle. are used in the electron transport chain to pump H+ into the thylakoid space. provide energy to Photosystem I and Photosystem II. power sugar synthesis during the Calvin cycle.
power sugar synthesis during the Calvin cycle.
Photoautotrophs -eat other organisms that use light energy to make food molecules. -produce organic molecules from inorganic molecules. -make sugar by using organic raw materials. -include only the green plants.
produce organic molecules from inorganic molecules
