Q&A Hero

Q: In the gluconeogenic pathway, the three regulated reactions of glycolysis catalyzed by ____, ____ and ____ are replaced by alternative reactions. a. glucokinase; PFK-1; pyruvate kinase b. phosphoglucoisomerase; PFK-1; pyruvate kinase c. PFK-1; triose phosphate isomerase; pyruvate kinase d. glucokinase; PFK-1; glyceraldehyde-3-phosphate dehydrogenase e. glucokinase; PFK-1; pyruvate carboxylase

Q: Glucose monitoring devices use the reaction, Glucose + O2+ H2O ï‚®gluconate + 2 ____, which is catalyzed by the enzyme ____. a. H2O; glucose hydrolase b. H2O; glucose oxidase c. H2O2; peroxidase d. H2O2; glucose oxidase e. H2O; gluconate synthase

Q: The major tissues carrying out gluconeogenesis are the ____ and ____. a. brain; muscles b. muscles; kidneys c. liver; kidneys d. liver; red blood cells e. red blood cells; brain

Q: A new photosystem from a plant with yellow-colored leaves was discovered to have a potential difference of 2.73 volts between the ground and excited states. What wavelength of light is required to excite an electron in this photosystem? a. 228 nm b. 455 nm c. 683 nm d. 910 nm e. none of the above

Q: The general flow of electrons in plant photosynthesis is from PSII to PSI. Which of the following correctly explains the events that occur during this process? a. The oxidation of water occurs at PSI with the electrons being passed to ferredoxin to reduce NADP+. b. Protons are pumped into the lumen at PSII during water reduction and also by the cytochrome bf complex allowing for ATP synthesis to occur. c. A cyclic flow of electrons is created between ferredoxin, cytochrome bf complex, and PSI that allows for the production of NADPH without the generation of ATP. d. For each electron removed from a water molecule, 2 photons are required to transfer it to ferredoxin. e. None of the above

Q: Which of the following is true regarding CO2fixation in plants? a. CAM plants work by storing carbon dioxide at night in the form of oxaloacetate b. The RUBISCO enzyme has a higher affinity for oxygen than for CO2, making it very difficult to effectively fix CO2 c. At high temperatures, C4 plants are more efficient than C3 plants because they are able to fix CO2 with minimal photorespiration d. The RUBISCO enzyme contains a Mg2+ that acts as a Lewis base, binding to CO2 and making it more susceptible to nucleophilic attack e. None of the above are true

Q: During photosynthesis-linked carbohydrate synthesis in plants, the products of photosynthesis are required for the actual fixation of carbon. Which of the following correctly explains the use of the products of photosynthesis? a. NADPH is required for the actual reduction of CO2 by the RUBISCO enzyme. b. ATP is used primarily during the regeneration of ribulose-1,5-bisphosphate c. Oxygen is used during the oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate d. Protons from the formation of the proton gradient are required to activate the RUBISCO enzyme e. Both A and B are correct

Q: CO2fixation is one of the most critical reactions on earth. Which of the following are elements of the reaction catalyzed by the RUBISCO enzyme? a. Mg2+ acts as a Lewis acid, binding to CO2 and making it more susceptible to nucleophilic attack b. The 6-carbon enzyme-bound intermediate that forms is split into 2 molecules of 3-phosphoglycerate c. Biotin is attached to a Lys residue in the active site and serves a critical role in the activation of CO2 d. ATP is required for the activation of CO2 prior to its reaction with ribulose-1,5-bisphosphate e. Both a and b occur

Q: All of the following are characteristics of CAM plants EXCEPT: a. the stroma are open during the night and closed during the day. b. they try to avoid loss of water by evaporation. c. there is an accumulation of CO2 fixation into the organic acids OAA and malate. d. during the night, dicarboxylic acid are stored within the vacuoles. e. CO2 is fixed by rubisco during the night.

Q: Which of the following set of pathways is similar between plants and animals? I. electron transport and the dark reactions of photosynthesis II. electron transport and the light reactions of photosynthesis III. the Hatch-Slack pathway (C-4) and pyruvate carboxylase a. I only b. II only c. III only d. I, III e. II, III

Q: The essential enzyme in C-4 plants used to conserve CO2 and avoid photophosphorylation is:a. rubisco.b. PEP carboxylase.c. glyceraldehyde-3-phosphate dehydrogenase.d. aldolase.e. ribulose-5-phosphate kinase.

Q: All of the following are characteristics of a C-4 plant EXCEPT: a. PEP carboxylase. b. transport of carbon dioxide and reducing power from the mesophyll cells to the bundle sheath cells. c. pyruvate-Pi dikinase. d. the expenditure of two high-energy phosphate bonds for each transport of carbon dioxide. e. carbon dioxide uptake in the daytime and fixation at night.

Q: How is photorespiration avoided in C-4 plants? a. decrease the concentration of phosphoglycolate. b. carry carbon dioxide towards an oxygen rich area of the plant. c. increase the concentration of ribulose-1,5-bisphosphate. d. transport of carbon dioxide from the mesophyll cells to the bundle sheath cells. e. none of the above.

Q: Although the ratio of carboxylase to oxygenase activity of rubisco is about ____ to one, the oxygenase activity diminishes plant productivity because of the loss of ____. a. one; rubisco b. two; ribulose-5-phosphate c. 3-4; ribulose-1,5-bisphosphate d. 6-8; rubisco e. 8-10; ribulose-5-phosphate

Q: The light-induced changes in chloroplasts which regulate key Calvin cycle enzymes include all EXCEPT: a. activation of rubisco activase. b. Mg2+ efflux from the thylakoid lumen. c. changes in stromal pH. d. generation of reducing power. e. all are true.

Q: To avoid futile cycling of carbohydrates: a. CO2 fixation by Calvin cycle proceeds in the dark. b. citric acid cycle, glycolysis and oxidative phosphorylation are inhibited when light is present. c. the enzymes of the Calvin cycle are inhibited by light reactions. d. plants do not have glycolytic and citric acid cycle enzymes. e. none of the above.

Q: The reaction, Ribulose-5-phosphate + ATP ->Ribulose-1,5-bisphosphate + ADP, is catalyzed by:a. phosphopentose isomerase.b. phosphoribulose kinase.c. ribulose bisphosphate carboxylase.d. phosphopentose epimerase.e. transketolase.

Q: All of the following are accomplished in the dark reactions of photosynthesis EXCEPT: a. carbon dioxide is fixed to ribulose-1,5-bisphosphate. b. two molecules of 3-phosphoglycerate are produced. c. glyceraldehyde-3-phosphate is used to synthesize glucose. d. glyceraldehyde-3-phosphate is used to re-synthesize ribulose-1,5-bisphosphate. e. ATP is produced.

Q: What type of enzyme catalyzes the reaction?sedoheptulose-7-P + glyceraldehyde-3-P xylulose-5-P + ribose-5-Pa. isomeraseb. lyasec. transaldolased. transketolasee. aldolase

Q: What type of enzyme catalyzes the reaction?Sedoheptulose-1,7-bisphosphate + H2O sedoheptulose-7-phosphate + Pia. hydrolaseb. isomerasec. aldolased. mutasee. lyase

Q: What type of enzyme catalyzes the reaction? Erythrose-4-P + dihydroxyacetone phosphate (DHAP) sedoheptulose-1,7-bisphosphate a. isomerase b. aldolase c. transaldolase d. transketolase e. mutase

Q: All are correct about reactions of the Calvin cycle EXCEPT: a. ATP is hydrolyzed to ADP. b. NADP+ is reduced to NADPH. c. an intermediate is fructose-1,6-bisphosphate. d. some of the enzymes are shared by glycolysis. e. involves a ribulose-5-phosphate kinase.

Q: Many of the enzymes of the Calvin cycle are also involved in ____; however, the glyceraldehyde-3-phosphate dehydrogenase of the Calvin cycle is specific for ____.a. glycolysis; NADPHb. citric acid cycle; NADHc. glycolysis; - FADH2d. citric acid cycle, NADPHe. none of the above

Q: The appropriate sequence of events for activation of rubisco is: A. carboxylation of E B. ribulose-1,5-bisphosphate released from E C. rubisco activase D. Mg2+ binding E. light flash a. C, E, D, A, B b. C, D, A, B, E c. B, C, D, A, E d. E, B, C, D, A e. E, C, B, A, D

Q: All are correct statements about rubisco EXCEPT: a. ribulose-1,5-bisphosphate and carbon dioxide are both substrates. b. the catalytic site has both carboxylase and oxygenase activity. c. it is found in the chloroplast stroma. d. it releases two molecules of glyceraldehyde-3-phosphate as products. e. it may be the most abundant enzyme in plants.

Q: Spinach chloroplasts are illuminated in the absence of ADP and Pi, then the light is turned off and ADP and Piare added. ATP is then synthesized for a short time in the dark. Which of the following best explains this? I. ATP is generated from the proton gradient accumulated in the light reactions. II. ATP synthesis stops after the proton gradient dissipates. III. ATP can be generated in the dark reactions if it becomes necessary for the plant to survive. a. I, III b. I only c. II only d. I, II e. II, III

Q: ____ and ____ are produced in the light reactions of photosynthesis which are used to convert ____ to ____. a. ATP; NADPH; carbon dioxide; sugar b. oxygen; ATP; NADPH; carbon dioxide c. ATP; NADP+; carbon dioxide; sugar d. oxygen; NADPH; ATP; sugar e. NADPH; ATP; sugar; carbon dioxide

Q: Which of the following is the product of cyclic photophosphorylation? a. NADPH b. Molecular oxygen c. ATP d. ADP and Pi e. Electron gradient

Q: Light-dependent electron flow with the production of ATP can occur without the formation of NADPH. This process is called ____, which involves only one of the photosystems, ____. a. noncyclic photophosphorylation; P700 b. cyclic photophosphorylation; P700 c. noncyclic photophosphorylation; photosystem II d. noncyclic photophosphorylation; P680 e. cyclic photophosphorylation; P680

Q: Which of the following is an outcome of ferredoxin passing electrons to cytochrome f/ cytochrome b6 complex? a. proton gradient formation b. ATP synthesis c. NADPH production d. oxygen evolution e. both A and B occur

Q: All are true for cyclic photophosphorylation EXCEPT: a. oxygen is evolved. b. utilizes cyt b6 of cyt f/cyt b6 complex. c. does not utilize ferredoxin. d. PS I is involved. e. all are true.

Q: Cyclic photophosphorylation takes place when: a. there is not enough light to activate the PSII complex. b. NADPH is high, therefore energy is used to drive the citrate cycle. c. ferredoxin is used to reduce the Mn-cluster. d. the proton gradient is not high enough to go all the way through the system. e. NADPH/NADP+ ratio is high, energy is used in generating ATP.

Q: Characteristics of the chloroplast's ATP synthase include all EXCEPT: a. contains CF1CF0 complex. b. heteromultimer of subunits. c. imbedded in the thylakoid membrane. d. has 14 c-subunits in its F0 rotor. e. all are true.

Q: The proton-motive force is composed of a ____ and a ____, and in photophosphorylation the ____ is greater. a. pH gradient; ATP/H+ ratio; ATP/ H+ ratio b. ATP/ H+ ratio; ion equilibrium; ion equilibrium c. membrane potential; pH gradient; membrane potential d. membrane potential; pH gradient; pH gradient e. ATP/ H+ ratio; membrane potential; membrane potential

Q: Photosynthetic phosphorylation and oxidative phosphorylation are similar processes. All of the following are common to BOTH processes EXCEPT: a. both have fixed and mobile electron carriers. b. both contain cytochromes in their electron carrier chains. c. both produce NADPH to be used in the reductive pentose phosphate pathway (Calvin cycle). d. both represent a major route of ATP synthesis. e. both have quinones as electron carriers.

Q: Photophosphorylation is the term for: a. activation of enzymes with light b. ATP synthesis driven by light energy c. dephosphorylation of ATP, resulting in a photon of light being released d. production of hexose from CO2 e. none are true

Q: Which statement regarding light is NOT true?a. the energy of a photon of light is calculated by E=hvb. the energy of 700nm light is greater than that of 400nm lightc. photosynthesis allows two electrons to flow for each pair of photons absorbed per centerd. the quantum yield of photosynthesis can be described as CO2 fixed per photon absorbed, or O2 evolved per photon absorbede. none are true

Q: The quantum yield of photosynthesis can be defined as the amount of ____ formed per equivalent of ____. a. photons; light input b. product; light input c. ATP; coenzyme Q d. carbohydrate; ATP e. none are true

Q: The product(s) of the R. viridisphotosynthetic reaction center is (are): a. mobile reduced quinone. b. NADPH. c. O2. d. reduced ferredoxin. e. protons.

Q: Via PSII and PSI, electrons ultimately flow from ____ to ____. a. NAPDH; O2 b. NADP+; water c. water; NADP+ d. O2; NADPH e. None are true

Q: All are properties of boththe P700 and P680 reaction centers EXCEPT: a. contain chlorophyll dimers. b. are electron donors. c. are activated by visible light. d. are involved in light-driven O2 evolution. e. all are properties.

Q: The essence of photosynthesis is the photochemical event which is: a. conversion of H2O to O2. b. reduction of NADP+. c. phosphorylation of ADP. d. light energy transduction to chemical energy. e. fixation of CO2.

Q: How many photons of light must be absorbed by PSII for the oxidation of 2 water molecules to form one oxygen molecule? a. 2 b. 4 c. 6 d. 8 e. 16

Q: All of the following are involved in the production of biochemical energy from light EXCEPT: a. electron transfer. b. Q-cycle. c. transmembrane pH gradient. d. ribulose-1,5-bisphosphate. e. chlorophyll.

Q: Many chlorophyll molecules absorb light and direct the energy to the reactive centers. The transfer of this absorbed energy is called: a. fluorescence transfer. b. redox transfer. c. resonance energy transfer. d. photochemical emission. e. energy transduction.

Q: Chlorophyll is located in the ____ of the chloroplast. a. thylakoid membranes associated with proteins b. thylakoid spaces associated with rubisco c. stroma d. inner membrane space e. outer membrane

Q: Properties of photosystem II (PSII) include all EXCEPT: a. light-driven O2 evolution. b. similar photosystem in photosynthetic bacteria. c. use quinines as terminal electron acceptors. d. found in cyanobacteria, green algae and higher plants. e. all are true.

Q: The photosynthetic unit includes all EXCEPT: a. antenna chlorophylls. b. the reactive center. c. oxidation of chlorophyll to a cationic free radical, Chl .+ . d. the cationic free radical is the Mg2+ ion. e. all are true.

Q: If A and B represent electron-transfer molecules adjacent to chlorophyll (Chl) in the membrane, fill in the reaction sequence:

Q: When light energy is absorbed by chlorophyll an electron is promoted to a higher orbital and then transferred to a suitable acceptor resulting in light energy conversion to chemical energy in a(n): a. isomerase reaction. b. mutase reaction. c. ligase reaction. d. oxidation-reduction reaction. e. none of the above.

Q: The light reactions in photosynthetic plants: a. reduce water to oxygen with the production of NADPH b. use NADP+ to oxidize water to oxygen, thus forming NADPH c. produce ATP and NADPH during cyclic photophosphorylation. d. involve the splitting of two water molecules to produce molecular oxygen. e. uses photons of visible light to effect the reduction of water to oxygen

Q: Which of the following statements about the light reactions of photosynthesis is true? a. There are two distinct photosystems, linked together by a mechanism similar to electron transport. b. The source for electrons is located in the stroma of the thylakoid. c. The Mn complex is the primary electron acceptor and is located on photosystem I. d. The ultimate electron donor is molecular oxygen. e. Plastoquinone is a fixed electron transporter in the system located in the inner membrane.

Q: Carotenoids have primary roles in photosynthesis as: a. accessory light-harvesting and photooxidation. b. accessory light-harvesting and photoprotection from reactive oxygen species. c. resonance transfer pigments and photooxidation. d. resonance transfer and photodiffusion protection. e. none are true.

Q: Characteristics of chlorophyll include all EXCEPT:a. iron-containing porphyrin.b. planar conjugated porphyrin ring.c. long-chain phytol tail.d. delocalized electrons in the aromatic ring.e. photoexcitable electrons.

Q: Chloroplasts differ from mitochondria in that: a. chloroplasts can not generate ATP. b. only mitochondria have a double membrane. c. in chloroplasts, the proton gradient is generated between the thylakoid lumen and the stroma. d. only the mitochondrion has DNA, RNA and ribosomes. e. chloroplasts do not utilize a Q-cycle.

Q: Balance the following reaction: ____ NADPH + ____ H++ ____ ATP + ____ CO2 + 12 H2 O ï‚®C6H12O6+ 12 NADP++ 18 ADP + 18 Pi a. 6; 6; 18; 6 b. 12; 12; 18; 3 c. 6; 6; 12; 6 d. 12; 12; 18; 6 e. 6; 6; 12; 3

Q: Chloroplasts consist of a folded inner membrane called the ____, which is organized into paired folds called ____. a. thylakoid membrane; stroma b. lamellae; thylakoid membrane c. thylakoid membrane; lamellae d. stroma; thylakoid membrane e. lamellae; stroma

Q: All are contained by chloroplasts EXCEPT: a. thylakoid membrane. b. ribosomes. c. DNA and RNA. d. stroma. e. all are true.

Q: The reaction of photosynthesis whereby light energy is transduced into chemical energy uses ____ as a source of carbon, and produces ____. a. CO2; hexose b. hexose; CO2 c. acetyl CoA; hexose d. CO2; acetyl CoA e. none of the above

Q: Photosynthesis occurs in photosynthetic ____ localized in large organelles known as ____. a. membranes; chloroplasts b. proteins; ribosomes c. matrix; chloroplasts d. membranes; photoplasts e. none are true

Q: If an ATP synthase contains 12 c subunits, 3 subunits and 3 subunits, how many protons must pass through this complex for every ATP molecule synthesized and transported to the cytosol, assuming that each ATP synthesized requires one proton for transport to the cytosol.a. 3b. 4c. 5d. 12e. 13

Q: A molecule such as 2,4-dinitrophenol works to uncouple the proton gradient. Which of the following is true about 2,4-DNP? a. 2,4-DNP is protonated in the matrix and deprotonated in the intermembrane space. b. The presence of an uncoupler results in an increase in the activity of the TCA cycle and electron transport c. 2,4-DNP is a very ineffective uncoupler because its hydrophobic structure prevents it from effectively crossing lipid bilayer membranes. d. 2,4-DNP has been used as a very effective diet aid for the past 70 years e. none of the above are correct

Q: If an ATP synthase contains 10 c subunits, 3 subunits and 3 subunits, how many protons must pass through this complex for every ATP molecule synthesized (assuming that all of the protons are used for ATP synthesis)?a. 0.3b. 3c. 3.3d. 10e. cannot be determined

Q: Which of the following is true regarding proton movement in the mitochondria? a. complex III pumps 2 protons across the inner membrane b. protons move from the matrix to the inner membrane space via the a and c subunits of ATP synthase to produce ATP c. 2,4-dinitrophenol moves protons from the inner membrane space to the matrix without ATP synthesis d. the matrix becomes acidic due to the proton movement coupled to electron transport e. none of the above

Q: Which of the following statements about mitochondrial transport systems is correct? a. malate-aspartate shuttle: converts cytosolic NADH to mitochondrial FADH2 b. ATP-ADP translocase: transfers ATP and a proton from matrix to cytosol while transferring ADP from cytosol to matrix c. glycerophosphate shuttle: converts cytosolic FADH2 to mitochondrial NADH d. the malate-aspartate shuttle is irreversible while the glycerophosphate shuttle is reversible e. none of the above are correct

Q: Which of the following correctly and completely describes electron movement in electron transport? a. NADH ï‚® complex I ï‚® complex III ï‚® coenzyme Q ï‚® Complex IV ï‚® O2 b. [FADH2] ï‚® complex II ï‚® cytochrome c ï‚® complex III ï‚® coenzyme Q ï‚® Complex IV ï‚® O2 c. NADH ï‚® complex I ï‚® coenzyme Q ï‚® complex III ï‚® cytochrome c ï‚® Complex IV ï‚® O2 d. [FADH2] ï‚® complex I ï‚® coenzyme Q ï‚®complex III ï‚® Complex IV ï‚® O2 e. none of the above

Q: Bacteria and other prokaryotic cells have the capacity to get more ATP/glucose oxidized than eukaryotic cells because ____, so they are more efficient. a. they are simpler and have less going on b. they don't have to use shuttles to reoxidize reduced nucleotides c. they do not have to translocate ATP-ADP across the mitochondrial membranes d. they use an electron transport chain that translocates more protons e. none of the above

Q: All are characteristics of the malate-aspartate shuttle EXCEPT: a. OAA translocates inner mitochondrial membrane. b. electrons of cytosolic NADH are translocated to mitochondrial NADH. c. two malate dehydrogenase enzymes. d. reactions are reversible. e. all are true.

Q: The malate-aspartate shuttle transfers ____ from cytosol to matrix while _____ moves from matrix to cytosol a. malate; glutamate b. -ketoglutarate; aspartate c. malate; -ketoglutarate d. aspartate; malate e. glutamate; malate

Q: All are correct about the glycerophosphate shuttle EXCEPT: a. there are two distinct forms of glycerol-3-phosphate dehydrogenase in cells with this shuttle. b. it results in the net transfer of electrons to the electron transport chain from NADH in the cytosol. c. glycerol-3-phosphate is translocated across the inner mitochondrial membrane into the matrix. d. electrons derived from this shuttle enter the electron transport chain at UQ. e. one form of glycerol-3-phosphate dehydrogenase is a flavoprotein.

Q: All are properties of glycerol-3-phosphate dehydrogenases EXCEPT: a. one is located in the cytosol. b. works to carry electrons into mitochondria. c. one is located in the inner mitochondrial membrane. d. mitochondrial enzyme has bound coenzyme Q. e. FAD-dependent mitochondrial enzyme.

Q: The reaction, dihydroxyacetone phosphate (DHAP) + NADH ï‚®NAD++ glycerol-3-phosphate, is catalyzed by: a. triose phosphate isomerase. b. glycerol kinase. c. DHAP dehydrogenase. d. glycerol-3-phosphate dehydrogenase. e. glycerol-3-phosphate reductase.

Q: A characteristic of the glycerophosphate shuttle is: a. It shuttles NADH across the mitochondrial membrane to yield 2.5 ATP/ADH. b. It shuttles "NADH electron equivalents" across the mitochondrial membrane to yield 1.5 ATP/NADH. c. It only operates efficiently when the [NADH] in the cytoplasm is higher than in the matrix. d. Malate is a key component in the shuttle process. e. Aspartate is a key component in the shuttle process.

Q: Which of the following molecules is LEAST LIKELY to be transported across the inner mitochondrial membrane? a. citrate b. NADH c. pyruvate d. phosphate e. malate

Q: All of the following are part of apoptosis EXCEPT: a. cytochrome c is released. b. caspases are activated. c. a series of proteolytic reactions. d. the mitochondrial outer membrane protein-permeable pores close. e. mitochondrial membrane permeabilization (MMP).

Q: What percentage of the proton gradient energy to synthesize and transport ATP to the cytosol is involved in the ATP-ADP transport? a. 10% b. 15% c. 25% d. 50% e. none of the above

Q: P/O ratio is defined as: a. Pi uptake per oxygen atom by mitochondria. b. molecules of phosphate released from ATP per oxygen utilized by muscle tissue. c. ratio of atoms of phosphorous to oxygen in phosphate (Pi). d. molecules of ATP formed per two electrons flowing through electron transport chain. e. none of the above.

Q: ____ creates a passive proton channel through which protons flow from the cytosol to the mitochondrial matrix in ____. a. Oligomycin; microorganisms b. Thermogenin (UCP1); brown adipose tissue c. Demerol; nerve tissue d. Obesin; adipocytes e. none of the above

Q: All are properties of uncouplers EXCEPT: a. They dissipate the proton gradient. b. ATP/ADP ratio increases. c. Electron transport continues. d. They were briefly used as weight-loss drugs. e. Heat is produced.

Q: What is the effect of first adding oligomycin and then 2,4-dinitrophenol to respiring mitochondria? a. First, electron transport and ATP synthesis speed up, then electron transport and ATP synthesis stops. b. First, ATP synthesis and electron transport stop, then electron transport speeds up with no ATP synthesis. c. First, electron transport speeds up while ATP synthesis stops, then electron transport and ATP synthesis stops. d. First, electron transport stops while ATP synthesis continues, then electron transport and ATP synthesis stops. e. Nothing, the uncoupler and inhibitor cancel each other out.