Chapter 8 Learning Curve
In animal cells, most ATP synthesis takes place in mitochondria, but in plant cells, most of the ATP used by plant cells is made in the chloroplasts. False True
False both takes place in mitochondria
The products of the Calvin cycle are 3-carbon sugars. true false
true
For every six CO2 molecules incorporated into carbohydrate molecules, how many triose phosphates can be exported from the chloroplast? 12 6 2 10 1
2
Which of the following are produced directly as a result of the movement of electrons through the photosynthetic electron transport chain? oxygen and carbohydrates ATP and NADPH carbohydrates and ATP water and carbohydrates
ATP and NADPH
Which of the following are products of the light-dependent reactions of photosynthesis that are required by reactions in the Calvin cycle? ATP and NADPH ATP and oxygen NADP+ and oxygen Water and NADPH
ATP and NADPH
In photosynthesis, the reduction of 3-phosphoglycerate to form carbohydrate requires: RuBP. ATP. ATP and NADPH. rubisco. NADPH.
ATP and NADPH.
Xanthophyll pigments: prevent formation of reactive oxygen species. absorb light energy. convert light energy into heat. reflect yellow light. All of these choices are correct.
All of these choices are correct.
Assuming that all is working properly, which of the following is at a higher energy level? An excited-state reaction center chlorophyll An excited-state antenna chlorophyll
An excited-state antenna chlorophyll
Which of the following is/are rubisco substrates? RuBP O2 CO2, O2, and RuBP CO2 and RuBP CO2
CO2, O2, and RuBP
The first photosynthetic organisms probably used chlorophyll as the primary light-absorbing pigment. true false
False Thus, the earliest interactions with sunlight may have been the evolution of UV-absorbing compounds that could shield cells from the sun's damaging rays.
During photosynthesis in plants and algae, ____ is oxidized and ____ is reduced. H2O; O2 H2O; CO2 O2; CO2 NADPH; ATP CO2; H2O
H2O; CO2
Which of the following statements is true regarding the Calvin cycle? The Calvin cycle is considered a "dark" reaction, because it is not directly related to photosynthesis. The Calvin cycle is a carefully regulated process because excess starch can be toxic to plant cells. The Calvin cycle uses a rare (and thus "rate-limiting") enzyme called rubisco. The action of rubisco is all that is necessary to produce high-energy triose phosphate from O2. None of the other answer options is correct.
None of the other anser options is correct "The Calvin cycle consists of 15 chemical reactions that synthesize carbohydrates from CO2. These reactions can be grouped into three main steps: (1) carboxylation, in which CO2 is added to a 5-carbon molecule; (2) reduction, in which energy and electrons are transferred to the compounds formed in step 1; and (3) regeneration of the 5-carbon molecule needed for carboxylation "
In plants and algae, which of the following is a by-product of photosynthesis? CO2 O2 carbohydrates C6H12O6 H+
O2
Which of the following compounds is required for the carboxylation step of the Calvin cycle? ATP and NADPH 3-PGA RuBP ATP NADPH
RuBP
The regeneration of RuBP typically limits the rate of photosynthesis under low light intensities. This is because: RuBP regeneration requires ADP. RuBP regeneration requires ATP. RuBP regeneration is part of the "dark reactions." photosynthesis occurs only in high light. None of the answer options is correct.
RuBP regeneration requires ATP.
The Calvin cycle includes 15 enzymes, most of which are involved in: RuBP regeneration. RuBP carboxylation. reduction. starch synthesis. ATP synthesis.
RuBP regeneration.
Which of the following correctly describes the role of rubisco in the Calvin cycle? Rubisco incorporates CO2 from the atmosphere into an organic molecule. Rubisco uses NADPH to reduce 3-phosphoglycerate to a three carbon sugar. Rubisco uses ATP to regenerate RUBP. None of the other answer options is correct.
Rubisco incorporates CO2 from the atmosphere into an organic molecule.
A researcher is carrying out an experiment where she labels a protein with a fluorescent tag (so she can visualize its location in a cell), and introduces this tagged protein into the lumen of a single thylakoid. She observes her treated cells periodically, and notices that the labeled protein can move between grana, but is never observed in the stroma. What can she deduce? This protein cannot easily diffuse through the thylakoid membrane. All thylakoid membranes and grana share a common lumen, through which the labeled protein can move. The protein likely travels through a common lumen shared by thylakoid membranes and grana, and cannot easily diffuse through the thylakoid membrane. This protein likely travels between different thylakoid membranes by moving through the stroma, but its movement through the stroma is very brief. This protein can easily transfer between the inner and outer mitochondria membranes.
The protein likely travels through a common lumen shared by thylakoid membranes and grana, and cannot easily diffuse through the thylakoid membrane.
Suppose a plant is exposed to a toxin that causes the thylakoid membranes to become much more permeable to protons than normal. Which of the following would be true? The carboxylation step of the Calvin cycle would be unaffected. The reduction and regeneration steps of the Calvin cycle would slow down and eventually stop. The reduction step of the Calvin cycle would slow down and eventually stop. The regeneration step of the Calvin cycle would slow down and eventually stop. The carboxylation and reduction steps of the Calvin cycle would slow down and eventually stop.
The reduction and regeneration steps of the Calvin cycle would slow down and eventually stop.
Which of the following is true concerning the Calvin cycle and light-harvesting reactions of photosynthesis? They take place in different organelles. They take place in different compartments of the same organelle. They take place in different types of cells in the plant None of the other answer options is correct.
They take place in different compartments of the same organelle.
All cells able to carry out photosynthesis have: a plasma membrane. chloroplasts and mitochondria. chloroplasts. mitochondria. chloroplasts, mitochondria, and a plasma membrane.
a plasma membrane.
From its ground state, photosystem II can: pull protons from H2O. pull electrons from H2O. pass electrons to photosystem I. absorb light energy. emit light energy.
absorb light energy.
Which of the following lowers the efficiency of plants' conversion of sunlight into chemical energy? the presence of antioxidants in the chloroplasts the presence of carotenoids in the chloroplasts increased carbon dioxide levels cold temperatures and bright sunlight
cold temperatures and bright sunlight
Which of the following is thought to be the first group of organisms able to use water as an electron donor in photosynthesis? land plants cyanobacteria algae aquatic plants
cyanobacteria
Low temperatures slow the activity of rubisco but enhance its ability to select CO2 over O2. Low temperatures thus: decrease photorespiration rates. increase photorespiration rates. increase photosynthesis rates. increase the production of reactive oxygen species.
decrease photorespiration rates.
Chemicals called uncouplers can make membranes permeable to small molecules and ions. What effect might un-couplers have on photosynthesis? decreased ATP production because the proton gradient would decrease increased ATP production because cyclic electron transport would increase decreased ATP production because the proton gradient would increase decreased NADPH production because the proton gradient would increase decreased NADPH production because the proton gradient would decrease
decreased ATP production because the proton gradient would decrease
How does the metabolism occurring in chloroplasts differ from that of mitochondria? None of the other answer options is correct. different electron sources different proton sources different electron acceptors different electron acceptors and electron sources
different electron acceptors and electron sources
In the Calvin cycle, ATP is required to: reduce RuBP. reduce 3-PGA. carboxylate RuBP. donate a phosphate group to 3-PGA. reduce triose phosphates.
donate a phosphate group to 3-PGA.
It is thought that the evolution of two photosystems from one likely involved: transfer of genetic material. gene duplication and divergence. either transfer of genetic material or gene duplication and divergence. both transfer of genetic material and gene duplication and divergence. endosymbiosis.
either transfer of genetic material or gene duplication and divergence.
Cyclic electron transport enhances ATP production because: ADP production increases. electrons are transferred from ferredoxin to plastoquinone. photosystem I pumps more protons. proton translocation decreases. cyclic electron transport is more energy efficient than linear electron transport.
electrons are transferred from ferredoxin to plastoquinone.
The process in which one cell takes up residence in another cell is called: endocytosis. parasitism. commensalism. exocytosis. endosymbiosis.
endosymbiosis.
Antennae accompany reaction centers, promoting _____. energy transfer H+ transfer electron transfer heat loss fluorescence
energy transfer
Eukaryotes conduct all of the photosynthesis that occurs in the ocean. true false
false "About half of oceanic photosynthesis is carried out by single-celled marine eukaryotes, while the other half is carried out by photosynthetic bacteria."
Prokaryotes account for roughly half of terrestrial photosynthesis. true false
false "Approximately 60% of global photosynthesis is carried out by terrestrial organisms, with the remaining 40% "
All photosynthetic bacteria possess two functionally distinct photosystems. false true
false some have one and some have 2 (cyanobacteria)
During photorespiration, the phosphoglycolate (PGO) produced by RuBP oxygenation is eventually converted to PGA; 75% of the carbon in PGO is recovered. How many molecules of PGO are required to generate two molecules of PGA through this route? five four three two one
four
Where does the oxygen come from that is produced as a by-product of photosynthesis? from the reduction of CO2 from the breakdown of carbohydrates from breakdown of water from the Calvin cycle
from breakdown of water
Where is the photosynthetic electron transport chain located in plant cells? in the outer membrane of the chloroplast in the stroma of the chloroplast in the thylakoid membranes of the chloroplast in the inner membrane of the chloroplast
in the thylakoid membranes of the chloroplast
With the endosymbiotic hypothesis in mind, what structure within modern-day chloroplasts is likely derived from the plasma membrane of ancestral cyanobacteria that took up residence within a eukaryotic cell? grana stroma lumen thylakoid membrane inner membrane
inner membrane
ATP production in photosynthesis requires: electrons. light. light and protons. light, electrons, and protons. protons.
light, electrons, and protons.
NADPH production in photosynthesis requires: light. electrons. protons. light and protons. light, electrons, and protons.
light, electrons, and protons.
Reactive oxygen species are detoxified in order to: minimize damage to membranes. enhance linear electron transport. recover electrons. enhance cyclic electron transport. All of these choices are correct.
minimize damage to membranes.
In addition to chloroplasts, which of the following organelles of eukaryotic cells is believed to have originated by endosymbiosis? mitochondria ribosomes lysosomes endoplasmic reticulum
mitochondria
In the Calvin cycle, NADPH is: oxidized. reduced. oxidized and reduced. None of the answer options is correct. phosphorylated.
oxidized.
Many photosynthetic prokaryotes are capable of cyclic electron transport only. It is likely that such organisms can _____ but not _____. produce NADPH; oxidize H2O reduce CO2; synthesize carbohydrates produce ATP; reduce H2O produce ATP; reduce CO2 produce NADPH; reduce CO2
produce ATP; reduce CO2
The occurrence of photorespiration _____ CO2 and _____ ATP. reduces; produces produces; produces oxidizes; produces produces; consumes consumes; consumes
produces; consumes
Which step of the Calvin cycle would be affected first by a lack of NADPH? carboxylation reduction All of these choices are correct. regeneration
reduction
Rubisco is characterized by: slow catalysis. fast catalysis. the ability to use two substrates. slow catalysis and the ability to use two substrates.
slow catalysis and the ability to use two substrates.
With the endosymbiotic hypothesis in mind, which of the following within modern-day chloroplasts is likely derived from the cytoplasm of ancestral cyanobacteria that took up residence within a eukaryotic cell? stroma grana thylakoid lumen thylakoid membrane inner chloroplast membrane
stroma
The Z scheme refers to: electron transport. proton translocation. the use of H2O as an electron source. the path of electrons between photosystem II and cytochrome b6f. the changes in the energy level of electron donors during the photosynthetic electron transport chain.
the changes in the energy level of electron donors during the photosynthetic electron transport chain
Photorespiration occurs because: rubisco is a selective catalyst. there is more O2 than CO2 in the atmosphere. rubisco is a slow catalyst. there is more O2 than CO2 and rubisco is a slow catalyst. there is more O2 than CO2 and rubisco is a selective catalyst.
there is more O2 than CO2 in the atmosphere.
In the chloroplasts of plant cells, the absorption of light energy and the movement of electrons along an electron transport chain occurs in the _____ and the synthesis of carbohydrates takes place in the _____. thylakoids; stroma thylakoids; matrix inner membrane; cytoplasm inner membrane; matrix inner membrane; stroma
thylakoids; stroma
Collectively, most photosynthesis carried out in the ocean is performed by single-celled organisms as opposed to large, multicellular marine plants. true false
true
In photosynthesis, the electrons from _____ are used to reduce _____. oxygen; NADPH water; carbon dioxide oxygen; carbohydrates water; carbohydrates
water; carbon dioxide
Photosystem I is a _____ than photosystem II. stronger oxidant and a stronger reductant weaker oxidant stronger oxidant stronger reductant weaker oxidant and a stronger reductant
weaker oxidant and a stronger reductant
