BIOC 385 Ex. 1 All Questions
Choose the answer below that correctly fills in each blank: GAP + ___(1)__ --> FBP --> [enzyme? (2)] --> F6P + GAP -->__(3)___ + __(4)___ (1) DHAP, (2) FBPase, (3) E4P, (4) X5P (1) Ru5P, (2) Aldolase, (3) CO2, (4) GAP (1) GAP, (2) FBPase, (3) X5P, (4) DHAP (1) GAP, (2) R5P kinase, (3) X5P, (4) E4P
(1) DHAP, (2) FBPase, (3) E4P, (4) X5P
Choose the answer below that correctly fills in each blank: S7P + __(1)___--> R5P + __(2)___ --> [enzyme? (3)] --> Ru5P --> [enzyme? (4)] --> RuBP (1) GAP, (2) X5P, (3) R5P epimerase, (4) R5P kinase (1) DHAP, (2) X5P, (3) R5P epimerase, (4) FBPase (1) GAP, (2) X5P, (3) FBPase, (4) sucrase (1) Ru5P, (2) RuBP, (3) R5P kinase, (4) GAPDH
(1) GAP, (2) X5P, (3) R5P epimerase, (4) R5P kinase
Choose the answer below that correctly fills in each blank: R5P --> [R5P isomerase] --> __(1)___-->__(2)_____+ __(3)___--> [RuBisCo] --> 2 __(4)___ (1) glucose, (2) CO2, (3) H2O, (4) ATP (1) GAP, (2) DHAP, (3) X5P, (4) X5P (1) Ru5P, (2) R5P, (3) H2O, (4) GAP (1) Ru5P, (2) RuBP, (3) CO2, (4) GAP
(1) Ru5P, (2) RuBP, (3) CO2, (4) GAP
The three stages of the Calvin cycle are__________________. (1) use ATP, NADPH, and CO2, (2) make a C3 molecule, and (3) regenerate the starting C3 molecule. (1) fix CO2, (2) make a C3 sugar, and (3) make glucose. (1) fix CO2, (2) use NADPH and ATP, and (3) regenerate the starting C5 molecule. (1) use a C5 sugar, (2) reduce CO2 with NADPH, and (3) use ATP to regenerate the starting C5 molecule.
(1) fix CO2, (2) use NADPH and ATP, and (3) regenerate the starting C5 molecule.
Choose the one true statement referring to photosynthesis. (A) The photosystem II and cytochrome b6f absorb photons, which are necessary for the activation of the photosynthetic electron transport system. (B) Chlorophyll molecules donate 2 electrons to a nearby electron acceptor for every photon that is absorbed. (C) NADP+ is reduced to form NADPH, which is then used in the Calvin-Benson cycle. (D) Electron transport is facilitated by the electron carriers ubiquinone and cytochrome c.
(C) NADP+ is reduced to form NADPH, which is then used in the Calvin-Benson cycle.
2-phosphoglycerate(2PG) is converted to phosphoenolpyruvate (PEP) by the enzyme enolase. The standard free energy change (deltaG°') for this reaction is +1.7 kJ/mol. If the cellular concentrations are 2PG = 0.5 mM and PEP = 0.1 mM, what is the free energy change at 37°C for the reaction 2PG <-> PEP? 5.8 kJ/mol -5.8 kJ/mol -2.4 kJ/mol +2.4 kJ/mol -4146.4 kJ/mol
-2.4 kJ/mol
Joseph Priestley did two experiments 1) a mouse in a sealed jar without a mint plant, and 2) a mouse in a jar with a mint plant. a) What did Priestley call the gas that the mint plant provided to the mouse to keep it alive in the sealed jar? b) How did his experiments disprove the Phlogiston Theory? c) What was needed to be sure the mint plant kept the mouse alive? 1) a) dephlogisticated air, b) they showed the mouse could live in a sealed jar, c) light 2) a) dephlogisticated air, b) they showed the mouse could live in a sealed jar, c) water 3) a) oxygen, b) they showed the mouse died in a sealed jar, c) water 4) a) dephlogisticated air, b) they showed the mouse could not live in a sealed jar, c) light 5) a) fixed air, b) they showed the mouse could live in a sealed jar, c) light
1) a) dephlogisticated air, b) they showed the mouse could live in a sealed jar, c) light
Which THREE of the following statements about autotrophs and heterotrophs on earth are TRUE? 1) heterotrophs are dependent on autotrophs to generate O2 from H2O in order to support aerobic respiration 2) heterotrophs evolved on earth before autotrophs 3) the majority of heterotrophs on earth do not use aerobic respiration as a form of energy conversion 4) the majority of autotrophs on earth require aerobic respiration in order to survive 5) heterotrophs that do not eat autotrophs every day will die in a short time 6) autotrophs depend on heterotrophs to oxidize sugar and release CO2 into the atmosphere 7) heterotrophs depend on autotrophs for conversion of light energy to chemical energy
1) heterotrophs are dependent on autotrophs to generate O2 from H2O in order to support aerobic respiration 4) the majority of autotrophs on earth require aerobic respiration in order to survive 7) heterotrophs depend on autotrophs for conversion of light energy to chemical energy
The products of the oxidative portion of the pentose phosphate pathway are carbon dioxide and ______. 2 NADPH + 1 Pentose phosphate 2 NADH + 1 hexose phosphate 2 NADP+ + 1 pentose phosphate 2 NADPH + 1 hexose phosphate
2 NADPH + 1 Pentose phosphate
What are the two products of the rubisco oxygenase reaction? 2-phosphoglycolate and 3-phosphoglycerate glycine and serine 2-phosphoglycolate and serine 3-phosphoglycolate and 2-phosphoglycerate
2-phosphoglycolate and 3-phosphoglycerate
Approximately how many ATP are synthesized per O2 molecule generated in photosynthesis light reactions? 4 3 8 12
3
What is the maximum number of covalent bonds a carbon atom can make? 6 8 2 4
4
What three statements below accurately describe favism? 1) Favism is caused by malarial parasites. 2) Favism is caused by elevated GSH levels in cells. 3) It is not known what causes favism. 4) Vicine in fava beans elevates ROS levels. 5) Mediterranean foods contain high levels of favism. 6) Reduced levels of ribulose-5P cause favism. 7) Favism results from eating fava beans. 8) Favism is caused by a G6PD deficiency.
4) Vicine in fava beans elevates ROS levels. 7) Favism results from eating fava beans. 8) Favism is caused by a G6PD deficiency.
In C3 plants CO2 is first incorporated into _____________, whereas in C4 and CAM plants the CO2 is first incorporated into _____________. A) 3-phosphoglycerate; oxaloacetate B) 3-phosphoglycerate; malate C) glyceraldehyde-3-phosphate; erythrose-4-phosphate D) dihydroxyacetone phosphate; malate
A) 3-phosphoglycerate; oxaloacetate
What is the key difference between the Biosphere 2 experiment conducted in the Arizona desert in the 1990s and the "forgotten" terrarium in England that likely explains why the Biospherians needed excess CO2 removed from the Biosphere after only a few months, but the biosphere of terrarium was still thriving after 40 years? A) The Biosphere 2 experiment had too many heterotrophs and not enough autotrophs to balance the gas exchange needed for self-containment. B) The Biosphere 2 experiment had too many autotrophs and not enough heterotrophs to balance the gas exchange needed for self-containment. C) The terrarium had grasshoppers that are very good at keeping the level of CO2 high enough for the plants to undergo carbon fixation. D) The Biosphere 2 experiment used goats for food, which are now known to produce excess carbon dioxide and led to an imbalance in gas exchange. E) The terrarium was kept in a closet without light and this allowed the plants to evolve into light-independent photosynthetic organisms.
A) The Biosphere 2 experiment had too many heterotrophs and not enough autotrophs to balance the gas exchange needed for self-containment.
What three mechanisms regulate the activity of enzymes required for the Calvin-Benson Cycle? A) activation of enzymes owing to elevation of pH and Mg2+ in the stroma B) dephosphorylation of enzymes by RuBisCo phosphatase C) phosphorylation of enzymes by RuBisCo kinase D) oxidation of reduced thiols by reduced thioredoxin E) reduction of disulfide bonds that inhibit enzyme activity F) enzyme activators that are present at higher levels in the light G) enzyme inhibitors that are expressed at higher levels in the absence of light. H) increased pH in the thylakoid lumen and increased Mn2+ in the stroma
A) activation of enzymes owing to elevation of pH and Mg2+ in the stroma E) reduction of disulfide bonds that inhibit enzyme activity G) enzyme inhibitors that are expressed at higher levels in the absence of light.
What three functional units were included in the experiment demonstrating that Peter Mitchell's proposal was correct in which a proton gradient is responsible for ATP synthesis? A) artificial membrane; bacteriorhodopsin, ATP synthase B) electrons; protons; ATP C) reconstituted vesicle; bovine heart muscle; photon energy D) NADH, FAD, Coenzyme Q
A) artificial membrane; bacteriorhodopsin, ATP synthase
Under what conditions do the wasteful side reaction of O2 with rubisco become significant? A) higher levels of soluble O2 than CO2 B) high levels of rubisco enzyme in the cytoplasm C) at night when the sun goes down and photosynthesis is limiting D) higher levels of soluble CO2 than O2 E) low temperatures and high moisture
A) higher levels of soluble O2 than CO2
The Biosphere 2 project, in Tucson, Arizona, was an experiment involving a large sealed terrarium with humans and photosynthetic plants living in balance. Why did the project have to be interrupted after only a few months? A) levels of CO2 rose to dangerous levels B) the plants stopped producing oxygen C) the rate of photosynthesis was too high D) the humans ran out of food
A) levels of CO2 rose to dangerous levels
How can an energetically unfavorable reaction occur in a metabolic pathway? A) link it to an energetically favorable reaction B) increase the temperature inside the cell to make it a favorable reaction C) energetically unfavorable reactions cannot occur in metabolic pathways D) link it to another energetically unfavorable reaction
A) link it to an energetically favorable reaction
Which is a way that light controls the Calvin cycle activity? A) reduced ferredoxin from the light reactions keeps thioredoxin reduced, which maintains the Calvin cycle enzymes in an active form B) High levels of ATP and NADPH from the light reactions inhibit the Calvin cycle enzymes C) Calvin cycle enzymes are inhibited by the lower H+, which is pumped out by the stroma by light reactions D) Calvin cycle enzymes activators are present at higher levels in the dark
A) reduced ferredoxin from the light reactions keeps thioredoxin reduced, which maintains the Calvin cycle enzymes in an active form
How do individuals with decreased levels of the pentose phosphate enzyme glucose-6-phosphate dehydrogenase respond to oxidative stress? A) they do not have the ability to regenerate reduced glutathione as rapidly as individuals with normal levels of the enzyme B) they have an increased ability to rapidly neutralize cellular levels of H2O2 and other reactive oxygen species C) they have elevated rates of metabolic flux through the pentose phosphate pathway activity D) they have higher than normal levels of NADPH, which leads to lower levels of oxidative stress
A) they do not have the ability to regenerate reduced glutathione as rapidly as individuals with normal levels of the enzyme
Identify the three labels in this energy diagram. A) catalytic efficiency, B) catalyzed reaction rate, C) exothermic reaction A) activation energy, B) transition state, C) change in free energy A) transition state, B) change in free energy, C) activation energy A) transition state, B) activation energy, C) change in free energy
A) transition state, B) activation energy, C) change in free energy
The amino acid sequence of a protein determine its structure. Which of the following statements is true? A) two proteins with nearly identical amino acid sequences should have very similar protein structures. B) protein folding is a random process and two proteins with identical sequences will fold into different structures. C) two proteins with similar amino acid sequences will most likely have evolved from two different ancestral genes. D) two proteins with different amino acid sequences will have similar protein structures because of natural selection.
A) two proteins with nearly identical amino acid sequences should have very similar protein structures.
Coenzymes are critical to many types of metabolic enzymes by providing chemical functionality to amino acid R groups. Identify each of the coenzyme structures shown here.
A. NADP+ B. FAD C. NADH D. Biotin E. NAD+ F. FADH2 G. NADPH
In the five steps used by photosynthetic organisms to convert solar energy into chemical energy, which molecules store the solar energy before sugar synthesis? ATP and NADPH NADH and FADH2 H2O and O2 chlorophylls
ATP and NADPH
The Calvin-Benson cycle requires which metabolites generated from the light reactions? ATP and NADPH NADH and FADH2 CO2 and ATP sucrose and GTP
ATP and NADPH
Which answer correctly classifies the compound with its relationship to aspartate transcarbamoylase? ATP; allosteric inhibitor CTP; substrate ATP; allosteric activator CTP; allosteric activator
ATP; allosteric activator
Select the TWO true statements from the list below regarding the structure and function of enzymes A) all proteins are not enzymes but all enzymes are proteins B) enzymes increase the rates of biochemical reactions without changing the equilibrium constatne C) enzyme cofactors can increase the chemical functionality of enzymes, which are otherwise limited by the R groups of amino acids D) the substrate can be predicted by simply knowing the structure of the unoccupied enzyme active site, similar to a key fitting a lock E) enzymes decrease the equilibrium constant of biochemical reactions and increase the rates of reactions from years to minutes
B) enzymes increase the rates of biochemical reactions without changing the equilibrium constatne C) enzyme cofactors can increase the chemical functionality of enzymes, which are otherwise limited by the R groups of amino acids
Coupled redox reactions consist of two ______reactions, one of which results in loss of electrons (______) and the other results in gain of electrons (______). An acronym to remember this is _________. A) enzyme, oxidation, reduction, Big Rig B) half, oxidation, reduction, Oil Rig C) half, reduction, oxidation, Oil Rig D) catalytic, oxidation, reduction, Leo Lion
B) half, oxidation, reduction, Oil Rig
What is the advantage of the increased branching in glycogen compared with amylopectin and amylose? A) starch breaks down quickly and leads to insulin release, glycogen is a slow release. B) it generates more nonreducing ends for efficient removal/addition of glucose residues. C) they glycogen particle has a larger diameter than the amylopectin particle. D) branch points provide more structural support to the "koosh" ball molecular integrity
B) it generates more nonreducing ends for efficient removal/addition of glucose residues.
In a hydrogen bond between a water molecule and another biomolecule: A) the hydrogen atom forms an ionic bond with a carbon on the other water B) the hydrogen bond typically forms between the oxygen atom of the water and the hydrogen on the other water C) a hydrogen ion on the water molecule from an ionic bond with the oxygen ion on the other water D) a hydrogen on the water molecule forms a covalent bond to a hydrogen atom on the other water
B) the hydrogen bond typically forms between the oxygen atom of the water and the hydrogen on the other water
What is the overall balanced reaction for the light reactions of photosynthesis? A) O2 + 2 NADPH + 3 ATP 2 H2O + 2 NADP+ + 3 ADP + 3 Pi B) 3 CO2 + 6 NADPH + 9 ATP + 6 H2O Glyceraldehyde-3-phosphate + 6 NADP+ + 9 ADP + 9 Pi C) 2 H2O + 8 photons + 2 NADP+ + 3 ADP + 3 Pi O2 + 2 NADPH + 3 ATP D) O2 + 8 photons + NADP+ + 3 ATP 2 H2O + NADP+ + 3 ADP + 3 Pi
C) 2 H2O + 8 photons + 2 NADP+ + 3 ADP + 3 Pi O2 + 2 NADPH + 3 ATP
What explains why primaquine-induced hemolytic anemia in individuals with a G6PD deficiency range from mild to severe even when given the same dose of primaquine? A) Because there is only one mutation in the G6PD gene that causes hemolytic anemia, but there are different manufacturers of primaquine. B) Because mild hemolytic anemia is hard to measure, whereas severe hemolytic anemia is easy to measure based on red blood cells. C) Because there are a large number of distinct mutations in the G6PD gene that affect enzyme activity to different degrees. D) Because it is difficult to measure the dose of primaquine accurately enough to ensure all patients received the same amount of drug. E) Because males and females have different G6PD gene variants and the studies did not take into account gender differences.
C) Because there are a large number of distinct mutations in the G6PD gene that affect enzyme activity to different degrees.
Which statement below most accurately describes catabolic and anabolic pathways? A) Both types of pathways require redox reactions to facilitate metabolic flux. B) Catabolic pathways synthesize new molecules and anabolic pathways degrade molecules. C) Catabolic pathways degrade molecules and anabolic pathways synthesize new molecules. D) Both types of pathways require ATP to facilitate metabolic flux.
C) Catabolic pathways degrade molecules and anabolic pathways synthesize new molecules.
What is the observed seasonal variation in atmospheric CO2 levels in Mauna Loa and what explains it? A) From April to October atmospheric CO2 levels decrease due to decreased plant growth and decreased carbon fixation. B) From October to April atmospheric CO2 levels increase due to increased plant growth and decreased carbon fixation. C) From April to October atmospheric CO2 levels decrease due to increased plant growth and increased carbon fixation. D) From April to October atmospheric CO2 levels increase due to increased plant growth and decreased carbon fixation.
C) From April to October atmospheric CO2 levels decrease due to increased plant growth and increased carbon fixation.
What is the biochemical basis for using primaquine as an antimalarial drug? A) Malarial parasites are unable to metabolize primaquine as a food source and die from lack of oxygen. B) Malarial parasites are acetylated on key surface proteins by the catalytic activity of the primaquine enzyme. C) Malarial parasites do not fully develop in the high ROS cellular environment induced by primaquine treatment. D) Primaquine induces the production of ADP, which competes with ATP as an energy source for the parasite. E) Primaquine is metabolized by liver enzymes to produce hydrochloric acid, which kills malarial parasites but not liver cells.
C) Malarial parasites do not fully develop in the high ROS cellular environment induced by primaquine treatment.
Enzyme active sites ___________. A) can only bind a single substrate at a time B) are nonspecific with regard to substrate binding C) are characterized as pocket or cleft D) always exclude water in catalyzed reactions
C) are characterized as pocket or cleft
Which of the following is the correct formula for glucose? C5H12O6 C6H12O6 C6H10O6 C5H10O5
C6H12O6
Light activation of the chloroplast electron transport system, located in the ___(1)___, results in proton translocation into the __(2)____. The oxidation of H2O takes place in the ___(3)___ and generates protons, which contribute to the differential proton gradient across the __(4)____. The delta pH across the ___(5)___ causes protons to flow __(6)___ through the chloroplast _____(7)________, leading to ATP synthesis in the ___(8)______. The final electron acceptor is _(9)___, which accepts a pair of electrons to produce NADPH in the __(10)____. The Calvin-Benson cycle in the __(11)___ uses the __(12)___ and NADPH produced by the photosynthesis electron transport system to convert _(13)_ CO2 to ______(14)_____, which is used to synthesize sucrose. A) 1) thylakoid membrane, 2) stroma, 3) thylakoid lumen, 4) thylakoid membrane, 5) stroma, 6) out, 7) ATP synthase complex, 8) stroma, 9) NADPH, 10) thylakoid membrane, 11) stroma, 12) ATP, 13) 3, 14) glyceraldehyde-3P B) 1) thylakoid membrane, 2) stroma, 3) thylakoid lumen, 4) thylakoid membrane, 5) thylakoid membrane, 6) out, 7) ATP synthase complex, 8) stroma, 9) NADP+, 10) stroma, 11) stroma, 12) ATP, 13) 6, 14) glyceraldehyde-3P C) 1) thylakoid lumen, 2) thylakoid membrane, 3) thylakoid membrane, 4) thylakoid membrane, 5) stroma, 6) out, 7) ATP synthase complex, 8) grana, 9) NADP+, 10) stromal membrane, 11) stroma, 12) ATP, 13) 6, 14) glyceraldehyde-3P D) 1) thylakoid membrane, 2) thylakoid lumen, 3) thylakoid lumen, 4) thylakoid membrane, 5) thylakoid membrane, 6) out, 7) ATP synthase complex, 8) stroma, 9) NADP+, 10) stroma, 11) stroma, 12) ATP, 13) 3, 14) glyceraldehyde-3P
D) 1) thylakoid membrane, 2) thylakoid lumen, 3) thylakoid lumen, 4) thylakoid membrane, 5) thylakoid membrane, 6) out, 7) ATP synthase complex, 8) stroma, 9) NADP+, 10) stroma, 11) stroma, 12) ATP, 13) 3, 14) glyceraldehyde-3P
How do mesophyll cell chloroplasts differ from those in bundle sheath cells? A) They are the same B) Bundle sheath cell chloroplasts lack PSI reaction centers C) Mesophyll cell chloroplasts lack PSII reaction centers D) Bundle sheath cell chloroplasts lack PSII reaction centers
D) Bundle sheath cell chloroplasts lack PSII reaction centers
As a protein folds, what are the stabilizing forces that help keep the protein from spontaneously unfolding? A) Hydrophilic amino acids in the interior and hydrophobic amino acids on the exterior. B) An increase in entropy in the surrounding water. C) A favorable change in free energy between the unfolded and folded states. D) Hydrophobic amino acids in the interior and hydrophilic amino acids on the exterior.
D) Hydrophobic amino acids in the interior and hydrophilic amino acids on the exterior.
Which statement regarding CAM plants is true? A) They are more efficient than C4 plants. B) They store CO2 in 3-phosphoglycerate before releasing it to the Calvin cycle. C) They use one cell type to absorb and store CO2 before utilizing it in the Calvin cycle in another cell type. D) They absorb CO2 at night and release it to the Calvin cycle during the day.
D) They absorb CO2 at night and release it to the Calvin cycle during the day.
Why is referring to the Calvin cycle reactions as the dark reactions a misnomer? A) They absorb, and do not reflect, the sunlight energy. B) They do not absorb sunlight energy. C) They do not absolutely require sunlight energy for a short period of time (seconds). D) They require an active photosynthetic system in the light, so are not the "dark reactions" in everyday biochemistry. E) They occur primarily at night.
D) They require an active photosynthetic system in the light, so are not the "dark reactions" in everyday biochemistry.
The five-step mechanism of ribulose bisphosphate carboxylase (rubisco)_________________. A) involves the incorporation of 3 CO2 molecules to yield one 3-phosphoglycerate molecule. B) involves C1, C3, C4, C5, and C6 molecules in the enzyme mechanism intermediates. C) is an overall thermodynamically unstable reaction. D) adds a CO2 molecule to a C5 ribulose sugar, yielding an unstable C6 molecule that cleaves into two C3 molecules.
D) adds a CO2 molecule to a C5 ribulose sugar, yielding an unstable C6 molecule that cleaves into two C3 molecules.
C4 plants are thought to be more efficient than C3 plants because they________________. A) make larger sugar molecules from CO2. B) can produce sugar molecules at night in addition to during the day. C) can live in dry climates. D) can concentrate the CO2 in chloroplasts and therefore minimize side reactions with O2.
D) can concentrate the CO2 in chloroplasts and therefore minimize side reactions with O2.
Raffinose-series oligosaccharides are hard for humans to digest because___________. A) they function as soluble decoys that inhibit pathogenic bacteria from invading the epithelial cells B) humans have a large number of competing glycan binding sites C) they bind to bifidobacteria in the gut D) humans do not have the enzyme necessary to hydrolyze the glycosidic bonds
D) humans do not have the enzyme necessary to hydrolyze the glycosidic bonds
The difference between an oxidation reaction and a reduction reaction is that oxidation is the ______________and reduction is the ______________. A) loss of protons; gain of protons B) gain of electrons; loss of electrons C) gain of protons; loss of electrons D) loss of electrons; gain of electrons
D) loss of electrons; gain of electrons
Which pairs of carbohydrate class and carbohydrate examples are correct? A) simple sugar:raffinose, polysaccharide: sucrose, glycoconjugate:keratan B) simple sugar:starch, polysaccharide:lactose, glycoconjugate:syndecan C) simple sugar:mucin, polysaccharide: chitin, glycoconjugate:cellulose D) simple sugar:sucrose, polysaccharide: chitin, glycoconjugate:syndecan
D) simple sugar:sucrose, polysaccharide: chitin, glycoconjugate:syndecan
The term greenhouse effect refers to the idea that_________________. A) the capacity of the earth's plant matter to store CO2 is increasing. B) the global production of plant matter is increasing. C) tropical rainforests are gradually being eliminated. D) the temperature of the earth is increasing because of heat trapped by gases such as CO2.
D) the temperature of the earth is increasing because of heat trapped by gases such as CO2.
The O2 generated from photosynthesis is derived from A) CO2 reduction to glycerate-3-phosphate B) water molecules that directly reduce PSI C) CO2 reduction to glycerate-3-phosphate D) water molecules that directly reduce PSII
D) water molecules that directly reduce PSII
What is the biochemical explanation for why G6PD deficiencies are so prevalent in Africa? A) G6PD deficiencies result in elevated NADPH levels, which are toxic to malarial parasites because the reducing power of NADPH is elevated. B) G6PD deficiencies result in elevated levels of reduced glutathione; malarial parasites can only survive when GS-SG levels are elevated. C) G6PD deficiencies result in elevated cellular ROS because of limiting NADPH; malarial parasites cannot survive with high levels of NADP+. D) G6PD deficiencies result in elevated cellular ROS because of limiting NADH; malarial parasites cannot survive in a low ROS environment. E) G6PD deficiencies result in elevated cellular ROS because of limiting NADPH; malarial parasites cannot survive in a high ROS environment.
E) G6PD deficiencies result in elevated cellular ROS because of limiting NADPH; malarial parasites cannot survive in a high ROS environment.
R is the highly active form of an allosteric enzyme and T is the less active form of enzyme. What would happen to [T]/[R] if substrate concentration is decreased? Decrease Increase Remain the same
Increase
What two basic approaches listed below would have the greatest impact on lowering atmospheric CO2 levels? Decrease the number of trees. Increase the number of gas powered vehicles. Increase the number of trees. Increase the size of the polar ice caps. Decrease the size of the Amazon river. Reduce the burning of fossil fuels.
Increase the number of trees. Reduce the burning of fossil fuels.
The Biosphere 2 project, in Tucson, Arizona, was an experiment involving a large sealed terrarium with humans and photosynthetic plants living in balance. Why did the project have to be interrupted after only a few months? The plants stopped producing oxygen. The rate of photosynthesis was too high. Levels of CO2 rose to dangerous levels. The humans ran out of food.
Levels of CO2 rose to dangerous levels.
If the equilibrium constant (Keq) is greater than 1, which direction will the reaction proceed? Not enough info to determine Spontaneously to products neither direction Spontaneously to reactants
Spontaneously to products
What is the name of this molecular complex and where is it located? The oxygen evolving complex found in PSII. The photosynthesis harvesting center found in PSI. The manganese center found in the cytochrome b6f complex. The tyrosine zeta center found in the light harvesting complex.
The oxygen evolving complex found in PSII.
Is the net reaction favorable for the following series of coupled reactions and what supports that conclusion? No, ΔG°' < 0 Yes, ΔG°' > 0 No, ΔG°' > 0 Yes, ΔG°' < 0
Yes, ΔG°' < 0
Put the following five steps of the photosynthetic electron transport system in the correct order to explain the processes required to convert solar energy into chemical energy. ____Chlorophyll is photo-oxidized and transfers an electron to pheophytin. ____ATP and NADPH in the stroma are used to convert CO2 to glyceraldehyde-3P. ____ATP is synthesized in response to protons flowing out of the thylakoid lumen through the ATP synthase complex. ____Photooxidation at the PSI reaction center leads to the generation of NADPH. ____A proton gradient is established across the thylakoid membrane.
__1__Chlorophyll is photo-oxidized and transfers an electron to pheophytin. __5__ATP and NADPH in the stroma are used to convert CO2 to glyceraldehyde-3P. __4__ATP is synthesized in response to protons flowing out of the thylakoid lumen through the ATP synthase complex. __3__Photooxidation at the PSI reaction center leads to the generation of NADPH. __2__A proton gradient is established across the thylakoid membrane.
Put the following steps in photosynthesis in the correct order to generate 2 NADPH and 3 ATP following the absorption of 8 photons and return of 12 H+ from the thylakoid space to the stroma. ____Oxidation of pheophytin initiates a series of redox reactions culminating in the reduction of 4 plastocyanin and translocation of 8 H+ across the thylakoid membrane. ____PSII absorbs 4 photons leading to photooxidation of 4 chlorophyll molecules and oxidation of 2 H2O to replace the 4 e- in chlorophyll and release 4 H+ into the thylakoid lumen. ____PSI absorbs 4 photons leading to the photooxidation of 4 plastocyanin and initiation of a series of redox reactions culminating in the reduction of 2 NADP+ to yield 2 NADPH. ____The sun comes up. ____A total of 12 H+ enter the chloroplast ATP synthase to generate 3 ATP when they return to the stroma and induce conformational changes in the head piece of the complex.
__3__Oxidation of pheophytin initiates a series of redox reactions culminating in the reduction of 4 plastocyanin and translocation of 8 H+ across the thylakoid membrane. __2__PSII absorbs 4 photons leading to photooxidation of 4 chlorophyll molecules and oxidation of 2 H2O to replace the 4 e- in chlorophyll and release 4 H+ into the thylakoid lumen. __4__PSI absorbs 4 photons leading to the photooxidation of 4 plastocyanin and initiation of a series of redox reactions culminating in the reduction of 2 NADP+ to yield 2 NADPH. __1__The sun comes up. __5__A total of 12 H+ enter the chloroplast ATP synthase to generate 3 ATP when they return to the stroma and induce conformational changes in the head piece of the complex.
The mitochondrial electron transport system and the photosynthetic electron transport system have a number of common biochemical features. For each of the mitochondrial electron transport system components listed on the left side of the table below, there is an analogous functional component of the photosynthetic electron transport system listed on the right side. Match the corresponding functional components. ____ 1/2 O2 ____ cytochrome c ____ complexes I, III, IV ____ intermembrane space ____ mitochondrial matrix ____ ubiquinone ____ NAD+ ____ NADH ____ inner membrane 1. cytochrome b6f 2. oxygen 3. plastoquinone 4. NADP+ 5. stroma 6. plastocyanin 7. thylakoid membrane 8. thylakoid lumen 9. water
__4__ 1/2 O2 __6__ cytochrome c __1__ complexes I, III, IV __8__ intermembrane space __5__ mitochondrial matrix __3__ ubiquinone __2__ NAD+ __9__ NADH __7__ inner membrane
Match each stage of the Calvin-Benson Cycle with its corresponding biochemical function. 1. 3-phosphoglycerate is oxidized to form glyceraldehyde-3P at the expense of ATP and NADPH 2. 3-phosphoglycerate is reduced to form glyceraldehyde-3P at the expense of ATP and NADPH 3. ribulose-1,5-bisphosphate is combined with CO2 to form two moles of 2-phosphoglycolate 4. glyceraldehyde-3P is used to reform ribulose-1,5-bisphosphate using the carbon shuffle 5. ribose-5P is combined with O2 to form two moles of 3-phosphoglycerate 6. ribulose-1,5-bisphosphate is combined with CO2 to form two moles of 3-phosphoglycerate ____ Stage 3 ____ Stage 1 ____ Stage 2
__4__ Stage 3 __6__ Stage 1 __2__ Stage 2
Mitochondria continually generate ROS, which can be damaging to cells with high rates of aerobic respiration. Put the following steps in the correct order to explain how ROS generated by mitochondria are neutralized by glutathione. Assume that NADPH levels need to first be maintained at a high level by the pentose phosphate pathway before ROS can be reduced. Removal of hydrogen peroxide is the final step. See Figure 14.9. ____A superoxide radical combines with 2 H+ and e- to generate hydrogen peroxide. ____G6PD reduces NADP+ to generate NADPH. ____Hydrogen peroxide is converted to water by the enzyme glutathione peroxidase in a reaction requiring reduced glutathione. ____Q cycle intermediate aberrantly donates e- to O2 ____Oxidized glutathione is reduced by glutathione reductase in a reaction requiring NADPH.
__4__A superoxide radical combines with 2 H+ and e- to generate hydrogen peroxide. __1__G6PD reduces NADP+ to generate NADPH. __5__Hydrogen peroxide is converted to water by the enzyme glutathione peroxidase in a reaction requiring reduced glutathione. __3__Q cycle intermediate aberrantly donates e- to O2 __2__Oxidized glutathione is reduced by glutathione reductase in a reaction requiring NADPH.
Resonance energy transfer from one chlorophyll in the photosystems results in______________. a reduced neighboring pheophytin molecule. heat release. a neighboring chlorophyll in an excited state. the release of a photon.
a neighboring chlorophyll in an excited state.
which two functional groups are involved in producing a peptide bond amino and thiol alcohol and amino methyl and amino amino and carboxyl
amino and carboxyl
During the daylight, Calvin-Benson cycle enzymes RuBisCO and FBPase-1 are activated by: a) Decreased pH and Mg2+ levels in the stroma b) Elevated pH and Mg2+ levels in the stroma c) Decreased pH and Mg2+ levels in the thylakoid lumen d) Elevated pH and Mg2+ levels in the thylakoid lumen
b) Elevated pH and Mg2+ levels in the stroma
What is the role of oxaloacetate in the Hatch-Slack pathway for C4 plants? a) To increase the solubility of O2 b) To serve as a transient CO2 carrier c) To eliminate the oxygenase reaction in rubisco and thereby block photorespiration d) To induce high levels of photorespiration
b) To serve as a transient CO2 carrier
The study of biochemistry attempts to explain the nature of life physical processes at the macromolecular level chemical processes at the atomic level biological processes at the molecular and cellular level
biological processes at the molecular and cellular level
Electrons from plastocyanin are passed on to_____________. cytochrome b6f plastoquinone chlorophyll P700+ chlorophyll P680+
chlorophyll P700+
In what location of the cell does the Calvin-Benson cycle occur? chloroplast stroma chloroplast grana thylakoid lumen cytoplasm
chloroplast stroma
The enzyme in the photosynthetic Z scheme that catalyzes the PQ cycle, which is analogous to Complex III and the Q cycle in the mitochondrial electron transport chain, is cytochrome b6f photosystem II plastocyanin photosystem I
cytochrome b6f
When there are high NADPH levels in the stroma, what is the result ofphotooxidation of P700? a) Dissociation of H+ gradient b) Decreased ATP synthesis c) NADP+ reduction d) Electron flow between ferredoxin and plastoquinone resulting in H+ translocation
d) Electron flow between ferredoxin and plastoquinone resulting in H+ translocation
Which of the following best define the first law of thermodynamics? a) there is no entropy at zero Kelvin b) all spontaneous processes in the universe tend toward dispersal of energy c) entropy is a measure of disorder d) total amount of energy in the universe is a constant
d) total amount of energy in the universe is a constant
If the Gibbs free energy change value for a reaction is less than zero, this reaction is _______. endothermic exergonic endergonic exothermic
exergonic
If the Gibbs free energy change value for a reaction is less than zero, this reaction is__________. endothermic. exothermic. endergonic. exergonic.
exergonic.
The molecular explanation for the observed human ABO blood types (A, B, AB, O) is _____________. decreased expression GTA, and increased expression of GTB. expression of Rh factor, GOT, and GTAB. expression of GTA, GTB, both, or neither. expression of GTO, GTB, GTA, and GTAB.
expression of GTA, GTB, both, or neither.
In the following series of reactions, what is the shared intermediate? fructose-1,6-P glucose-6-P ATP fructose-6-P
fructose-6-P
Light activation of photosynthesis causes stromal pH to _________ from pH 7 to pH ___________. This causes __________ in Mg2+ in the _________, which ________ enzymes in the Calvin-Benson cycle. decrease; 6; increases, lumen, activates increase; 8; increases, stroma, activates decrease; 6, decreases, lumen, activates increase; 8, increases, stroma, inhibits
increase; 8; increases, stroma, activates
Binding of glucose to hexokinase causes a conformational change in the enzyme. This is an example of the __________ model of enzyme catalysis. substrate induced glove and hand lock and key induced fit
induced fit
The function of chloroplasts in plant cells is to convert ___________. chemical energy to heat energy light energy to chemical energy heat energy to light energy heat energy to chemical energy
light energy to chemical energy
Flux is defined as the rate at which __________is/are interconverted. enzymes sugars metabolites energy
metabolites
Energy conversion in living systems is required for what three types of work? osmotic work, photosynthetic work, mechanical work osmotic work, chemical work, potential work kinetic work, chemical work, mechanical work osmotic work, chemical work, mechanical work
osmotic work, chemical work, mechanical work
The photosynthetic Z scheme describes the oxidation of H2Oand production of ATP and NADPH synthesis of glucose from CO2. movement of electrons driven by the reflection of light energy. oxidation of NADPH. production of CO2.
oxidation of H2Oand production of ATP and NADPH
Cyclic photophosphorylation generates ATP without producing NADPH and __________. plastoquinone carbon dioxide water oxygen
oxygen
hydrogen bonds form between hydrogen and ___________ or hydrogen and __________ hydrogen, oxygen oxygen, nitrogen carbon, nitrogen nitrogen, hydrogen
oxygen, nitrogen
Antibiotics such as penicillin and methicillin inhibit bacterial cell wall synthesis. Identify the structure shown here. A)penicillin-activated bacterial transpeptidase B) penicillin-inhibited bacterial transpeptidase C) beta lactamase-inhibited bacterial transpeptidase D) MRSA-activated methicillin transpeptidase
penicillin-inhibited bacterial transpeptidase
Plants convert light energy into chemical energy by the process of ___________. electron transport photorespiration photooxidation carbon fixation
photooxidation
What chemical process is able to take place in the presence of solar energy? hydrolysis anaerobic respiration hydrogenation photosynthesis
photosynthesis
Experimental evidence based on measuring bond energies between DNA strands using all combinations of G, C, A, and T stacked bases demonstrates that the DNA double helix is stabilized by noncovalent interactions between nucleotides owing to __________ . hydrogen bonding ionic interactions sigma bonds pi-pi stacking
pi-pi stacking
Where do electrons come from to reduce the oxidized P700+ state in PSI? plastoquinone NADPH plastoquinol H2O plastocyanin O2
plastocyanin
Amino acids are the building blocks for which biomolecules? micelles proteins carbohydrates nucleic acids
proteins
The following picture is an example of what phenomenon? photooxidation resonance energy transfer fluorescence electron transfer
resonance energy transfer
The following picture is an example of what phenomenon? resonance energy transfer photoexcitation electron transfer fluorescence
resonance energy transfer
Which carbohydrates are generated by the Calvin-Benson Cycle for plant survival? glucose, fructose, glycogen chitin, cellulose, galactose aldose, deoxyribose, sucrose starch, cellulose, sucrose
starch, cellulose, sucrose
What two factors control the rate of metabolic flux? A) substrate binding and enzyme catalysis B) glucose levels and enzyme activity C) substrate levels and enzyme activity D) substrate levels and ATP levels
substrate levels and enzyme activity
During photophosphorylation, the protons are pumped into the __________, and the ATP is made in the __________. thylakoid lumen; cytoplasm thylakoid lumen; stroma cytoplasm; stroma stroma; thylakoid lumen
thylakoid lumen; stroma
A hydrogen bond can best be described as a ________________. strong ionic interaction. strong covalent interaction. weak covalent interaction. weak noncovalent interaction.
weak noncovalent interaction.
Under what conditions does cyclic photophosphorylation take place? in an acidic stroma with high levels of NADPH with high levels of ATP with an inactivated photosystem I
with high levels of NADPH
Under what conditions does cyclic photophosphorylation take place? in an acidic stroma with high levels of NADH with low levels of ATP with an inactivated photosystem I with high levels of ATP
with low levels of ATP
Calculate the free energy change at 37°C for the reaction convertingGlucose-6-phosphate to Fructose-6-phosphate, given that ΔGº' is +1.7 kJ/mol and the cellular concentrations are G6P = 1.2 mM and F6P = 0.15 mM. ΔG = ΔG° + RTlnQ Q = [C]i[D]i/[A]i[B]i
ΔG = 1.7kJ/mol + (8.315 J/mol K)(310K) ln (0.15mM/1.2mM) ΔG = 1.7kJ/mol + (-5.36 kJ/mol) ΔG = -3.66 kJ/mol