Ch. 5 Microbiology (#22-28)
Select the correct sequence of steps as energy is extracted from glucose during cellular respiration. a) electron transport chain → citric acid cycle → glycolysis → acetyl CoA b) glycolysis → citric acid cycle → acetyl CoA → electron transport chain c) glycolysis → acetyl CoA → citric acid cycle → electron transport chain d) citric acid cycle → electron transport chain → glycolysis → acetyl CoA e) acetyl CoA → citric acid cycle → electron transport chain → glycolysis
c) glycolysis → acetyl CoA → citric acid cycle → electron transport chain Glycolysis produces pyruvic acid, which enters the mitochondrion. There, it is converted to acetyl CoA, which enters the citric acid cycle. Electron carriers bring electrons from the first three steps to the electron transport chain, and ATP is made.
Which statement describes the citric acid cycle? a) This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration. b) This process converts pyruvic acid to acetyl CoA. c) This process splits glucose in half and produces 2 ATPs for each glucose. d) This process produces some ATP and carbon dioxide in the mitochondrion. e) This process joins 2 pyruvic acid molecules into a molecule of glucose.
d) produces some ATP and CO2
Which of the following equations represents photosynthesis? a) C6H12O6 + 6O2 → 6CO2 + 6H2O b) C6H12O6 + 6CO2 → 6O2 + 6H2O c) 6CO2 + 6O2 → C6H12O6 + 6H2O d) 6H2O + 6O2 → C6H12O6 + 6CO2 e) 6CO2 + 6H2O → C6H12O6 + 6O2
e) 6CO2 + 6H2O → C6H12O6 + 6O2 Photosynthesis requires carbon dioxide and water for the production of sugar and oxygen.
What connects the two photosystems in the light reactions? a) A chain of glucose molecules b) A thylakoid c) The Calvin cycle d) Chlorophyll e) An electron transport chain
e) ETC https://image.slidesharecdn.com/manjuetc-150816094558-lva1-app6891/95/electron-transport-chain-etc-7-638.jpg?cb=1439718458
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain? a) chloroplast b) Golgi apparatus c) nucleus d) lysosome e) mitochondrion
e) Mitochondria
Which statement describes the electron transport chain? a) This process produces some ATP and carbon dioxide in the mitochondrion. b) This process converts pyruvic acid to acetyl CoA. c) This process splits glucose in half and produces 2 ATPs for each glucose. d) This process joins 2 pyruvic acid molecules into a molecule of glucose. e) This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.
e) captures e- and makes most the ATP
Sort the statements into the appropriate bin depending on whether they correctly or incorrectly describe some aspect of the electron transport chain and chemiosmosis.
CORRECT: -The final electron acceptor is O2. -A chemical that inactivates cytochrome c so that it can't pass electrons on to cytochrome a would block electron transport and ATP synthesis. -A toxin that causes a leak to form in the inner mitochondrial membrane such that protons could bypass the ATP synthase would prevent oxidative phosphorylation. -The pH of the intermembrane space in mitochondria would be lower than the pH of the mitochondrial matrix in an actively metabolizing cell. INCORRECT: -The electrons carried by FADH2 have more potential energy than those carried by NADH. -Electrons moving from the FMN to Q to cytochrome b are gaining energy. -A toxin that causes a leak to form in the inner mitochondrial membrane such that protons could bypass the ATP synthase would disrupt the flow of electrons to O2. -ATP serves as an electron carrier in the electron transport chain.
The image below shows three different oxidation-reduction equations. Sort each of the lettered items on the image into the proper bin. Electron donors Electron acceptors Oxidized product Reduced product
Electron donors: a, e, i Electron acceptors: b, f, j Oxidized product: c, g, k Reduced product: d, g, l
Place the major steps of cellular respiration in order by dragging the appropriate figure to each box. NADH + FADH2 --> -electrons- --> ATP, O2, H2O Glucose --> 2 pyruvic acid, 2 NADH, 2 ATP Acetyl CoA --> NADH, FADH2, CO2, ATP
[C6H12O6] 1. Glucose --> 2 pyruvic acid, 2 NADH, 2 ATP 2. Acetyl CoA --> NADH, FADH2, CO2, ATP 3. NADH + FADH2 --> -electrons- --> ATP, O2, H2O [CO2 and H2O] Order: Glycolysis, formation of acetyl CoA, Krebs cycle, electron transport, and chemiosmosis. Glycolysis is the initial process in cellular respiration as well as in fermentation. Formation of acetyl CoA, Krebs cycle, electron transport, and chemiosmosis are processes that are common to both aerobic respiration and anaerobic respiration but are not found in fermentation reactions.
Arrange the components of the electron transport chain in order from least electronegative to most electronegative thereby indicating the path of electrons through the electron transport chain.
[LEAST] NADH dehydrogenase, Coenzyme Q, Cytochrome b-c1 complex, Cytochrome c, Cytochrome oxidase complex, O2 [MOST]
What provides electrons for the light reactions? a) H2O b) O2 c) The Calvin cycle d) Light e) CO2
a) H2O Electrons are stripped from water in the light reactions of photosynthesis. This is one of the reasons plants need water.
Which of the following is true of aerobic respiration compared to anaerobic respiration? a) Aerobic respiration uses oxygen as a final hydrogen acceptor, whereas anaerobic respiration uses an inorganic molecule other than oxygen as the final electron acceptor. b) Aerobic respiration is less efficient than all forms of anaerobic respiration, producing less ATP and largerend-products. c) Aerobic respiration and anaerobic respiration both require oxygen as a final electron acceptor. d) Aerobic respiration uses oxygen as a final electron (hydrogen) acceptor, whereas anaerobic respiration uses an organic molecule.
a) In anaerobic respiration, the final electron (hydrogen) acceptor is an inorganic substance other than oxygen, such as nitrate, sulfate, or carbonate.
Iron is considered an essential element for many bacteria. Based on the animation, how would lack of iron affect energy production of a bacterium? a) Lack of iron would mean lack of heme, and thus lower amounts of functioning cytochrome proteins. This would mean lower energy yields. b) Lack of iron would mean that most of the oxygen could be reduced to form water, improving energy yields. c) Lack of iron would not have any affect on this system.
a) Lack of iron would mean lack of heme, and thus lower amounts of functioning cytochrome proteins. This would mean lower energy yields.
Which of the following is an acid produced by fermentation? a) Lactic acid and propionic acid b) Pyruvic acid c) Lactic acid d) Propionic acid e) Ethanol
a) Lactic acid and propionic acid http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/Articleimage/2017/GC/c6gc03036j/c6gc03036j-s2_hi-res.gif
Why do NAD+ and FAD NOT appear in the overall equation? a) The NAD+ and FAD are initially reduced then oxidized to their original state, so they do not appear in the net equation. b) Glucose and CO2 are the electron carriers in this pathway. c) This pathway doesn't use electron carriers such as NAD+ and FAD and uses only the electron transport chain. d) ADP is the electron carrier in this pathway and picks up electrons to form ATP.
a) The NAD+ and FAD are initially reduced then oxidized to their original state, so they do not appear in the net equation. At least 10 NAD+ and 2 FAD are used in the cellular respiration pathway. They pick up electrons during oxidation reactions in glycolysis, oxidation of pyruvate to form acetyl CoA, and the Krebs cycle, and then they give up these electrons to the electron transport chain. They don't appear in the net reaction equation because all of the NAD+ and FAD that enter into the reactions are oxidized back to their original form when they give up their electrons.
Which of the following situations does not result in a breakdown of the proton gradient? a) Uncoupling proteins b) Cyanide poisoning c) Oxygen deprivation
a) Uncoupling proteins
Select all statements that correctly describe the preparatory step and the Krebs cycle. a) The potential energy in the pyruvate is transferred to the reduced coenzymes (NADH and FADH2). b) There are five oxidation-reduction reactions depicted. c) It takes two "turns" of the Krebs cycle to process the pyruvic acid molecules resulting from the glycolysis of one glucose molecule. d) This process occurs in mitochondria in both eukaryotes and prokaryotes. e) Carbons from pyruvic acid end up as CO2. f) CO2 serves as the electron acceptor. g) The equivalent of one ATP is made for each turn of the Krebs cycle. h) The oxaloacetic acid that accepts the acetyl group is regenerated, enabling the cyclic nature of this process.
a, b, c, e, g, h https://ka-perseus-images.s3.amazonaws.com/c7052763740cb431d8e989fa55460816cc5a074c.png
Which of the following are features of allosteric inhibition? a) Allosteric inhibition can be reversed. b) In order to function, allosteric inhibitors must have structural similarity to the enzyme substrate. c) Allosteric inhibition can be irreversible. d) The allosteric inhibitor binds to a site distinct from the active site resulting in decreased affinity of the enzyme for the substrate. e) Allosteric inhibition can be overcome by increasing the amount of substrate in the reaction.
a, c, d During the process of allosteric inhibition, the allosteric inhibitor binds to a site on the enzyme distinct from the active site in order to alter its function. In glycolysis, one key step controlled by an allosteric inhibitor is the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate. The enzyme that catalyzes this reaction is allosterically inhibited by several different molecules including ATP. When ATP levels are high (indicating that the cell doesn't need to produce more glucose), it binds to the enzyme. This allosteric inhibition slows glycolysis and the process of ATP generation.
Compare and contrast three metabolic pathways by choosing whether the statement applies to anaerobic respiration. a) Process involves the Krebs cycle b) A total of 2 ATP are produced per molecule of glucose input. c) Much or most of the ATP produced is produced by oxidative phosphorylation. d) Process involves electron transport and chemiosmosis e) A total of 38 ATP are produced per molecule of glucose input. f) Process includes glycolysis g) End products may include lactic acid or ethanol. h) End products are CO2 and H2O i) The coenzyme NAD+ plays an important role in the pathway. j) Between 2 and 38 ATP are produced per molecule of glucose input. k) Can generate ATP in the absence of O2.
a, c, d, f, i, j, k
Compare and contrast three metabolic pathways by choosing whether the statement applies to aerobic respiration. a) Much or most of the ATP produced is produced by oxidative phosphorylation. b) End products may include lactic acid or ethanol. c) The coenzyme NAD+ plays an important role in the pathway. d) A total of 2 ATP are produced per molecule of glucose input. e) Process involves the Krebs cycle f) Between 2 and 38 ATP are produced per molecule of glucose input. g) Process includes glycolysis h) Process involves electron transport and chemiosmosis i) End products are CO2 and H2O j) A total of 38 ATP are produced per molecule of glucose input. k) Can generate ATP in the absence of O2.
a, c, e, g, h, i, j https://qph.fs.quoracdn.net/main-qimg-38049ddaf05154a0e98473ee29aabe7b-c
Select all statements that correctly describe glycolysis. a) Glucose is the original electron donor. b) CO2 is produced during glycolysis. c) Each of the 10 steps in this pathway is catalyzed by the same enzyme. d) The 6-carbon skeleton of glucose is enzymatically split into two 3-carbon compounds. e) More ATP is formed than is consumed in this process. f) This process occurs in the mitochondria of eukaryotic cells. g) Glyceraldehyde 3-phosphate is oxidized, and NAD+ is reduced to NADH. h) Pyruvate is the electron acceptor.
a, d, e, g https://image.slidesharecdn.com/biochem-glycolysisnarration-140421100344-phpapp02/95/glycolysis-pathway-in-cells-7-638.jpg?cb=1398074785
Why might some cells uncouple the electron transport chain? a) A cell does not require ATP. b) Cells can use the energy from the proton gradient for functions other than producing ATP, such as heat generation. c) Uncoupling proteins offset the effect of cyanide. d) Too much ATP is bad for the cell.
b) Cells can use the energy from the proton gradient for functions other than producing ATP, such as heat generation.
Why is glucose such a good source of energy for bacteria? a) Glucose contains six carbon atoms, which can be quickly incorporated into organic cellular constituents needed for growth. b) Glucose is a highly reduced compound, containing many carbon-hydrogen bonds and a lot of potential energy. c) Glucose contains six oxygen atoms, which can be used for oxidative phosphorylation and the generation of many ATP molecules. d) Glucose is a highly oxidized compound, containing many carbon-hydrogen bonds and a lot of potential energy.
b) Glucose is a highly reduced compound, containing many carbon-hydrogen bonds and a lot of potential energy. Highly reduced compounds contain a lot of hydrogen. The potential energy stored in these bonds can be released to do work. During oxidation of glucose, the energy stored in carbon-hydrogen bonds is transferred to an electron carrier such as NAD+, and is ultimately captured in ATP, providing energy to the cell.
What is the role of pyruvic acid in fermentation? a) It becomes the final electron acceptor for the electron transport chain in the absence of oxygen. b) It takes the electrons from NADH, oxidizing it back into NAD+. c) It provides the protons to be used in the electron transport chain. d) It is the organic acid end-product of fermentation.
b) It takes the electrons from NADH, oxidizing it back into NAD+. Pyruvic acid is a yellowish organic acid that occurs as an intermediate in many metabolic processes, especially glycolysis.
The light reactions take place in the _________ and the Calvin cycle takes place in the _________. a) stroma; thylakoids b) thylakoids; stroma c) chloroplasts; mitochondria d) inner membrane; outer membrane e) mitochondria; chloroplasts
b) Light Dep: thylakoids & Light Indep: stroma
Which of the following can be used as a final electron acceptor for aerobic respiration? a) Nitrate ion, sulfate ion and carbonate ion can all be used as a final electron acceptor. b) Molecular oxygen c) Sulfate ion d) Carbonate ion e) Nitrate ion
b) O2
Why does lack of oxygen result in the halt of ATP synthesis? a) It causes one of the cytochromes in the electron transport chain to be permanently stuck in the reduced state. b) The chain shuts down and can no longer pump hydrogen ions across the membrane, and the proton gradient cannot be maintained. c) Oxygen prevents uncoupling of the electron transport chain.
b) The chain shuts down and can no longer pump hydrogen ions across the membrane, and the proton gradient cannot be maintained.
How does an enzyme lower the activation energy of a reaction? a) As the enzyme is utilized, heat is released causing an increase in the reaction rate and a subsequent lowering in the energy of activation. b) The enzyme increases the effectiveness of reactant collisions thereby increasing the number of reactant molecules that reach activation energy. c) The enzyme increases the potential energy available to the reactants, thereby decreasing the activation energy that must be reached. d) The breakdown of the enzyme provides energy to the reactants allowing them to reach activation energy more quickly.
b) The enzyme increases the effectiveness of reactant collisions thereby increasing the number of reactant molecules that reach activation energy.
Compare and contrast three metabolic pathways by choosing whether the statement applies to fermentation. a) End products are CO2 and H2O b) The coenzyme NAD+ plays an important role in the pathway. c) Can generate ATP in the absence of O2. d) Much or most of the ATP produced is produced by oxidative phosphorylation. e) End products may include lactic acid or ethanol. f) Process involves electron transport and chemiosmosis g) Process involves the Krebs cycle h) Between 2 and 38 ATP are produced per molecule of glucose input. i) A total of 38 ATP are produced per molecule of glucose input. j) A total of 2 ATP are produced per molecule of glucose input. k) Process includes glycolysis.
b, c, e, j, k
What two molecules are produced by the light reactions and used to power the Calvin cycle? a) C6H12O6 and RuBP b) G3P and H2O c) ATP and NADPH d) C6H12O6 and O2 e) CO2 and O2
c) ATP and NADPH ATP and NADPH are both products of the light reactions and are used to power the Calvin cycle. Carbon dioxide enters a plant through the stomata; it is not produced in the light reactions. Oxygen is a product of the Calvin cycle.
In which of the following organelles does photosynthesis take place? a) Mitochondrion b) Nucleus c) Chloroplast d) Central vacuole e) Ribosome
c) Chloroplast Chloroplasts use energy from light to transform carbon dioxide and water into sugar and oxygen.
Why does FADH2 yield less ATP than NADH? a) FADH2 binds directly to the ATP synthase enzyme. b) FADH2 electrons ultimately do not go to oxygen. c) FADH2 electrons enter the electron transport chain at a lower energy level. d) Electrons from FADH2 cannot pump hydrogen ions out of the cell.
c) FADH2 electrons enter the electron transport chain at a lower energy level. https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/110/2016/05/03200406/Figure_07_04_01.jpg
Which of the following processes takes place in the cytosol of a eukaryotic cell? a) citric acid cycle b) electron transport chain c) glycolysis d) acetyl CoA formation e) ATP production by ATP synthase
c) Glycolysis
What is the fate of the NAD+ newly regenerated by fermentation? a) It is converted into an organic acid. b) It is oxidized into carbon dioxide. c) It returns to glycolysis to pick up more electrons. d) It is converted into ethanol.
c) It returns to glycolysis to pick up more electrons. [2 NAD+ --> 2 NADH + 2H+] https://image.slidesharecdn.com/cellrespirationrevised09-100916211016-phpapp02/95/cell-respiration-65-728.jpg?cb=1284671486
What is one difference between ubiquinones and cytochromes? a) Ubiquinones cannot carry electrons; cytochromes can. b) Ubiquinones can only be oxidized; cytochromes can only be reduced. c) Ubiquinones are not made of protein; cytochromes are. d) Ubiquinones can only be reduced; cytochromes can only be oxidized.
c) Ubiquinones are not made of protein; cytochromes are. Ubiquinones are coenzymes found everywhere in animals and most bacteria. Ubiquinones are a class of compounds that occur in all living cells & act as electron-transfer agents in cell respiration. They are substituted quinones. Cytochromes are iron containing hemeproteins central to which are heme groups that are primarily responsible for the generation of ATP via electron transport. Cytochrome compounds consistof heme bonded to a protein. Cytochromes function as electron transfer agents in many metabolic pathways, especially cellular respiration.
What is the intermediate product formed by pyruvic acid during alcoholic fermentation? a) Lactic acid b) Formic acid c) Ethanol d) Acetaldehyde e) Carbon dioxide
d) Acetaldehyde [*Glycolysis* --> 2 Pyruvate --> 2CO2 and 2 Acetaldehyde --> 2 Ethanol] http://bio1903.nicerweb.com/doc/class/bio1151/Locked/media/ch09/09_17FermentationA.jpg
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle? a) G3P (C3H6O3) b) Sucrose (C12H22O11) c) RuBP d) Carbon dioxide (CO2) e) Glucose (C6H12O6)
d) CO2 Carbon dioxide provides the carbon atoms that are incorporated into sugars in photosynthesis. This is why plants need to take in carbon dioxide.
How does cyanide poisoning result in the decrease of ATP production? a) Cyanide permanently binds to oxygen, preventing its use as the final electron acceptor. b) Cyanide permanently oxidizes cytochrome a3, preventing other components to change into the reduced state. This causes the proton gradient to break down, stopping ATP synthesis. c) Cyanide uncouples the proton gradient from the process of ATP synthesis. d) Cyanide permanently reduces cytochrome a3, preventing other components to change into the oxidized state. This causes the proton gradient to break down, stopping ATP synthesis.
d) Cyanide permanently reduces cytochrome a3, preventing other components to change into the oxidized state. This causes the proton gradient to break down, stopping ATP synthesis. It acts similarly to oxygen deprivation.
Which of the following statements about fermentation is true? a) It allows the electron transport chain to continue in the absence of oxygen. b) It provides additional protons to allow the electron transport chain to continue. c) It is an alternative way for a cell to produce oxygen. d) It is an alternative way to return electron carriers to their oxidized state.
d) It is an alternative way to return electron carriers to their oxidized state. Fermentation is a metabolic process that consumes sugar in the absence of oxygen. The products are organic acids, gases, or alcohol.
What transports electrons from the light reactions to the Calvin cycle? a) Chlorophyll b) FADH2 c) An electron transport chain d) NADPH e) NADH
d) NADPH NADPH is an electron carrier that picks up electrons in the light reactions and releases them in the Calvin cycle.
How does the proton gradient help ATP synthase to make ATP? a) Protons move along the membrane. b) Protons are not involved with this step; only electrons are. c) Protons move from inside the membrane to outside the membrane. d) Protons move from outside the membrane to inside the membrane.
d) Protons move from outside the membrane to inside the membrane. (Oxidative Phosphorylation). The electrons from from NADH and FADH2 flow through the electron transport chain in the inner mitochondrial membrane generating a H+ buildup in the inner membrane space. This proton gradient (gradient of H+) flowing through the membrane enzyme complex ATP synthetase is the direct energy source for producing ATP.
One of the environmental changes that P. multocida encounters during infection is the limitation of nutrients and oxygen. One of the changes that P. multocida (a facultative anaerobe) makes in this environment is to switch to anaerobic metabolism. Predict which of the following is most likely to occur as a result of the switch from aerobic to anaerobic metabolism. a) The amount of ATP produced will be relatively the same as aerobic metabolism because P. multocida will be able to respire anaerobically. b) Glycolysis, the Kreb's cycle, and electron transport will function as usual except that a different compound will be used as a final electron acceptor. c) During anaerobic metabolism, different electron carriers will be utilized; these will ultimately lead to less ATP production and slower growth of the organism. d) The organisms will grow more slowly because they will produce less ATP compared to aerobic metabolism.
d) The organisms will grow more slowly because they will produce less ATP compared to aerobic metabolism.
What is the correct general equation for cellular respiration? a) C6H12O6 + 6H2O → 6CO2 + 6O2 + ATP energy b) 6O2 + 6H2O + ATP energy → C6H12O6 + 6CO2 c) C6H12O6 + 6CO2 → 6O2 + 6H2O + ATP energy d) 6CO2 + 6H2O + ATP energy → C6H12O6 + 6O2 e) C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy
e) C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy
Which statement describes glycolysis? a) This process converts pyruvic acid to acetyl CoA. b) This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration. c) This process produces some ATP and carbon dioxide in the mitochondrion. d) This process joins 2 pyruvic acid molecules into a molecule of glucose. e) This process splits glucose in half and produces 2 ATPs for each glucose.
e) splits a glucose in half to make 4 ATP total