Microbiology - Chapter 5
Which of the following is the best definition of oxidative phosphorylation? Electrons are passed through a series of carriers to O2. A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP. ATP is directly transferred from a substrate to ADP. Electrons are passed through a series of carriers to an organic compound.
A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.
What is the function of GTP? An electron carrier A scaffolding for carbon atoms An energy carrier An oxidizer to produce CO2
An energy carrier
Which of the following statements regarding metabolism is FALSE? ATP is formed in catabolic reactions.Heat may be released in both anabolic and catabolic reactions. Anabolic reactions are degradative. ADP is formed in anabolic reactions.
Anabolic reactions are degradative.
The reactions involved in producing larger compounds from smaller compounds is called Metabolism Anabolism Catabolism
Anabolism
What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle? RuBP Carbon dioxide (CO2) G3P (C3H6O3) Sucrose (C12H22O11) Glucose (C6H12O6)
Carbon dioxide (CO2)
Where does the energy required for anabolic reactions come from? Unused energy from metabolism Catabolic reactions Heat
Catabolic reactions
In which of the following organelles does photosynthesis take place? Nucleus Mitochondrion Central vacuole Chloroplast Ribosome
Chloroplast
Which of the following matches enzyme components with their correct definition and/or function? Apoenzymes are typically inorganic molecules, such as iron, zinc, or magnesium. Apoenzymes are the non-protein component of an enzyme. Cofactors are the protein components of enzymes. Coenzymes are the organic cofactors important to enzyme activity.
Coenzymes are the organic cofactors important to enzyme activity.
Which of the following statements regarding competitive inhibitors is true? The inhibitor will degrade the substrate. Competitive inhibitors decrease the rate of enzyme activity. The inhibitor will destroy the substrate. The inhibitor will destroy the enzyme.
Competitive inhibitors decrease the rate of enzyme activity.
What enables competitive inhibitors to bind to a specific enzyme? Competitive inhibitors cover the entire surface of an enzyme. Competitive inhibitors have structures that resemble the enzyme's substrate. Competitive inhibitors have unique sugars that are attracted to the enzyme. Competitive inhibitors form unique covalent bonds with enzyme structures.
Competitive inhibitors have structures that resemble the enzyme's substrate.
How does cyanide poisoning result in the decrease of ATP production? 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. 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. Cyanide uncouples the proton gradient from the process of ATP synthesis. Cyanide permanently binds to oxygen, preventing its use as the final electron acceptor.
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.
Which of the following is a bacterium that performs oxygenic photosynthesis? Purple sulfur bacteria Green sulfur bacteria Purple nonsulfur bacteria Green nonsulfur bacteria Cyanobacteria
Cyanobacteria
What occurs at the bridge step? The formation of succinyl CoA Decarboxylation of pyruvic acid The production of GTP The formation of oxaloacetate
Decarboxylation of pyruvic acid
Assume you are growing bacteria on a lipid medium that started at pH 7. The action of bacterial lipases should cause the pH of the medium to decrease. increase. stay the same.
Decrease
Noncyclic photophosphorylation employs which photosystem(s)? Photosystem I Photosystem II Both photosystem I and photosystem II Neither photosystem I nor photosystem II
Both photosystem I and photosystem II
Compare and contrast three metabolic pathways by choosing whether the statement applies to aerobic respiration.
End products are CO2 and H2O Process involves electron transport and chemiosmosis A total of 38 ATP are produced per molecule of glucose input. Process includes glycolysis The coenzyme NAD+ plays an important role in the pathway. Much or most of the ATP produced is produced by oxidative phosphorylation
Compare and contrast three metabolic pathways by choosing whether the statement applies to fermentation.Check all that apply.
End products may include lactic acid or ethanol. The coenzyme NAD+ plays an important role in the pathway. Process includes glycolysisCan generate ATP in the absence of O2. A total of 2 ATP are produced per molecule of glucose input.
Where does the energy come from to power the formation of GTP? ATP Succinyl CoA Water NADH
Succinyl CoA
Where does the energy to excite the electrons in photosystem I come from? Sunlight Water ATP NADPH Cytochromes Chlorophyll
Sunlight
Why is the Calvin-Benson cycle also termed the "light independent reactions" of photosynthesis? Sunlight is not directly needed to carry out this process. No chlorophyll molecules are used. It only occurs at night. It can use any wavelength of light to carry out the reactions.
Sunlight is not directly needed to carry out this process.
A key feature of cellular respiration is the removal of electrons from fuel molecules (oxidation) and the ultimate acceptance of these electrons by a low-energy electron acceptor. The process involves the use of electron carriers, NAD+ and FAD, which play crucial roles in multiple steps of the metabolic pathways. The overall equation for cell respiration is shown below. Why do NAD+ and FAD NOT appear in the overall equation? C6H12O6+6O2+38ADP+38Pi→6CO2+6H2O+38ATP
The NAD+ and FAD are initially reduced then oxidized to their original state, so they do not appear in the net equation.
Why does lack of oxygen result in the halt of ATP synthesis? Oxygen prevents uncoupling of the electron transport chain. It causes one of the cytochromes in the electron transport chain to be permanently stuck in the reduced state. The chain shuts down and can no longer pump hydrogen ions across the membrane, and the proton gradient cannot be maintained.
The chain shuts down and can no longer pump hydrogen ions across the membrane, and the proton gradient cannot be maintained.
According to the animation, what does the electron transport chain do to the concentration of hydrogen ions (protons)? The concentration of protons is lower outside the membrane than inside. The concentration of protons inside the membrane is equal to the concentration outside of the membrane. The concentration of protons is higher outside the membrane than inside.
The concentration of protons is higher outside the membrane than inside.
Why is reduction the term used to describe the gain of an electron? The electron acceptor gets smaller. The electron acceptor's net charge decreases. The amount of energy in the molecule decreases. The number of molecules in the reaction decreases.
The electron acceptor's net charge decreases.
Examine the figure above depicting the preparatory step and the Krebs cycle, and identify statements that correctly describe these processes.
The equivalent of one ATP is made for each turn of the Krebs cycle.Carbons from pyruvic acid end up as CO2.It takes two "turns" of the Krebs cycle to process the pyruvic acid molecules resulting from the glycolysis of one glucose molecule.The oxaloacetic acid that accepts the acetyl group is regenerated, enabling the cyclic nature of this process.There are five oxidation-reduction reactions depicted.The potential energy in the pyruvate is transferred to coenzymes NAD+ and FAD.
How does a noncompetitive inhibitor reduce an enzyme's activity? The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site. The inhibitor degrades the enzyme's normal substrate. The inhibitor degrades the enzyme. The inhibitor inactivates the enzyme.
The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site.
Which of the following statements about substrate-level phosphorylation is FALSE? It occurs to a lesser degree in the Krebs cycle than in glycolysis. It involves the direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP. No final electron acceptor is required. The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP. It occurs in glycolysis.
The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP.
Where do the electrons from photosystem I ultimately go after they are passed through the electron transport proteins? They are pumped out of the cell. They go to form water. They return to photosystem I. They are pumped into the cell.
They return to photosystem I.
Which of the following is TRUE about this reaction? NO3-+ 2H+ NO2- + H2O Nitrate ion Nitrite ion This process occurs anaerobically. This process requires the entire electron transport system. This process requires light. This process requires O2. This process requires O2 and the electron transport system.
This process occurs anaerobically.
Which statement describes the citric acid cycle? This process splits glucose in half and produces 2 ATPs for each glucose. This process converts pyruvic acid to acetyl CoA. This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration. This process joins 2 pyruvic acid molecules into a molecule of glucose. This process produces some ATP and carbon dioxide in the mitochondrion.
This process produces some ATP and carbon dioxide in the mitochondrion.
Which statement describes glycolysis? This process splits glucose in half and produces 2 ATPs for each glucose. This process converts pyruvic acid to acetyl CoA. This process joins 2 pyruvic acid molecules into a molecule of glucose. This process produces some ATP and carbon dioxide in the mitochondrion. This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.
This process splits glucose in half and produces 2 ATPs for each glucose.
Which statement describes the electron transport chain? This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration. This process converts pyruvic acid to acetyl CoA. This process joins 2 pyruvic acid molecules into a molecule of glucose. This process produces some ATP and carbon dioxide in the mitochondrion. This process splits glucose in half and produces 2 ATPs for each glucose.
This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.
How many molecules of ATP can be generated from one molecule of NADH? One Three Four Two
Three
What is the role of light energy in photosynthesis? To produce a proton gradient to make ATP To produce carbon dioxide To make glucose in the Calvin-Benson cycle To manufacture chloroplasts
To produce a proton gradient to make ATP
T/F: An apoenzyme that loses its coenzyme subunit will be non-functional.
True
How many net ATPs can be made from one molecule of glucose in glycolysis? One Four Six Two
Two
What is the net production of ATP in glycolysis? Six ATP Two ATP Four ATP Eight ATP
Two ATP
What is one difference between ubiquinones and cytochromes? Ubiquinones can only be oxidized; cytochromes can only be reduced. Ubiquinones can only be reduced; cytochromes can only be oxidized. Ubiquinones cannot carry electrons; cytochromes can. Ubiquinones are not made of protein; cytochromes are.
Ubiquinones are not made of protein; cytochromes are.
Which of the following situations does not result in a breakdown of the proton gradient? Oxygen deprivation Cyanide poisoning Uncoupling proteins
Uncoupling proteins
According to the animation, what does oxygen get reduced to at the end of the electron transport chain? Protons ATP Electrons NADH Water
Water
Which of the following is used in photosynthesis by both plants and cyanobacteria? Sunlight Carbon dioxide Water Water, sunlight, and carbon dioxide
Water, sunlight, and carbon dioxide
What is the most acidic place in the figure? a b c d e
a
The process of generating ATP using a proton gradient is referred to as water damming. chemiosmosis. the electron transport chain.
chemiosmosis.
Which of the following uses CO2 for carbon and H2 for energy? chemoautotroph chemoheterotroph photoautotroph photoheterotroph
chemoautotroph
Which of the following uses glucose for carbon and energy? chemoautotroph chemoheterotroph photoautotroph photoheterotroph
chemoheterotroph
What molecule is used to capture light energy? Chlorophyll Water ATP Carbon dioxide NADPH
chlorophyll
Which of the following compounds is NOT an enzyme? dehydrogenase β-galactosidase cellulase coenzyme A sucrase
coenzyme A
An enzyme, citrate synthase, in the Krebs cycle is inhibited by ATP. This is an example of all of the following EXCEPT competitive inhibition. noncompetitive inhibition. feedback inhibition. allosteric inhibition.
competitive inhibition.
Refer to the figure. In aerobic respiration, where is water formed? a b c d e
d
In the figure, where is ATP produced? a b c d e
e
Which of the following processes takes place in the cytosol of a eukaryotic cell? acetyl CoA formation citric acid cycle electron transport chain glycolysis ATP production by ATP synthase
glycolysis
Select the correct sequence of steps as energy is extracted from glucose during cellular respiration. glycolysis → acetyl CoA → citric acid cycle → electron transport chain electron transport chain → citric acid cycle → glycolysis → acetyl CoA acetyl CoA → citric acid cycle → electron transport chain → glycolysis glycolysis → citric acid cycle → acetyl CoA → electron transport chain citric acid cycle → electron transport chain → glycolysis → acetyl CoA
glycolysis → acetyl CoA → citric acid cycle → electron transport chain
In cellular respiration of glucose, what are the three principal stages? Calvin-Benson cycle, electron transport chain, and glycolysis glycolysis, Krebs cycle, and the electron transport chain fermentation, Krebs cycle, and electron transport chain chemiosmosis, photophosphorylation, and reduction
glycolysis, Krebs cycle, and the electron transport chain
Microorganisms that catabolize sugars into ethanol and hydrogen gas would most likely be categorized as homolactic fermenters. alcohol fermenters. aerobic respirers. anaerobic respirers. heterolactic fermenters.
heterolactic fermenters.
According to the animation, oxidative phosphorylation requires a net input of energy. is an anabolic process. is a catabolic process. makes larger compounds from smaller ones.
is a catabolic process.
The Pentose Phosphate Pathway is a part of photosynthesis. is another name for fermentation. is an example of anabolism. is an example of catabolism.
is an example of anabolism.
The use of amino acids to make proteins is an example of anabolism. is an example of catabolism. involves the production of ATP. is a completely efficient reaction.
is an example of anabolism.
In metabolism, energy that is not used is given off as heat. is used to break down large molecules into smaller ones. is stored in the form of ATP. is used to build up large compounds from smaller ones.
is given off as heat.
In the figure, the path labeled "2" is the flow of electrons. glucose. protons. energy. water.
protons
Which of the following actions would increase enzymatic activity in a bacterial cell that normally thrives in the human body? slightly increasing the temperature within the optimum range placing the bacteria in the refrigerator increasing the substrate level in the environment beyond saturation adding a second substrate that can act as a competitive inhibitor
slightly increasing the temperature within the optimum range
How is ATP generated in the reaction shown in the figure? photophosphorylation fermentation glycolysis oxidative phosphorylation substrate-level phosphorylation
substrate-level phosphorylation
Much of the energy released in catabolic reactions is captured in ATP for use in other reactions. When the phosphate is transferred directly from an organic molecule to ADP in order to produce ATP without an energized membrane, what has occurred? cyclic photophosphorylation noncyclic photophosphorylation oxidative phosphorylation substrate-level phosphorylation
substrate-level phosphorylation
Glycolysis literally means sugar producing. Embden-Meyerhof. sugar splitting. energy producing.
sugar splitting
During an oxidation reaction, the acceptor molecule gains an electron and becomes oxidized. the donor molecule loses an electron and becomes oxidized. the donor molecule gains an electron and becomes oxidized. the acceptor molecule loses an electron and becomes oxidized.
the donor molecule loses an electron and becomes oxidized.
Which of the following is the best definition of fermentation? the complete catabolism of glucose to CO2 and H2O. the production of energy by oxidative-level phosphorylation. the production of energy by both substrate and oxidative phosphorylation. the partial oxidation of glucose with organic molecules serving as electron acceptors. the partial reduction of glucose to pyruvic acid.
the partial oxidation of glucose with organic molecules serving as electron acceptors
The advantage of the pentose phosphate pathway is that it produces all of the following EXCEPT precursors for the synthesis of amino acids. NADPH. three ATPs. precursors for the synthesis of glucose. precursors for nucleic acids.
three ATPs.
The light reactions take place in the _________ and the Calvin cycle takes place in the _________. inner membrane; outer membrane stroma; thylakoids thylakoids; stroma mitochondria; chloroplasts chloroplasts; mitochondria
thylakoids; stroma
What type of reaction is in the figure? oxidation transamination dehydrogenation reduction decarboxylation
transamination
A bacterial culture grown in a glucose-peptide medium causes the pH to increase. The bacteria are most likely oxidizing the glucose. not growing. fermenting the glucose. using the peptides.
using the peptides.
Which of the following molecules is broken down in cellular respiration, providing fuel for the cell? Glucose ATP Water O2
Glucose
Consider the glycolysis pathway.
Glyceraldehyde 3-phosphate is oxidized, and NAD+ is reduced to NADH.Glucose is the original electron donor.The 6-carbon skeleton of glucose is enzymatically split into two 3-carbon compoundsMore ATP is formed than is consumed in this process.
Which of the following statements about glycolysis is true? Glycolysis is also called the Embden-Meyerhof pathway. All cells perform glycolysis. Glycolysis is the main source of NADH in the cell. Glycolysis produces glucose.
Glycolysis is also called the Embden-Meyerhof pathway.
In which organism would you likely find a chlorosome? Purple sulfur bacteria Purple nonsulfur bacteria Algae Cyanobacteria Green sulfur bacteria
Green sulfur bacteria
In noncyclic photophosphorylation, O2 is released from H2O. chlorophyll. C6H12O6. CO2. sunlight.
H2O
According to the animation, what is the net total (gain or loss) of ATP after one cycle? Loss of nine Loss of six No net gain or loss Gain of three Gain of six Loss of three
Loss of nine
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain? Golgi apparatus mitochondrion lysosome chloroplast nucleus
mitochondrion
Gallionella bacteria can get energy from the reaction Fe2+ → Fe3+. This reaction is an example of reduction. the Calvin-Benson cycle. fermentation. oxidation. photophosphorylation.
oxidation.
If a cell is starved for ATP, which of the following pathways would most likely be shut down? Krebs cycle glycolysis pentose phosphate pathway Krebs cycle and glycolysis
pentose phosphate pathway
Which organism is NOT correctly matched to its energy source? photoautotroph - CO2 photoheterotroph - light chemoautotroph-NH3 chemoautotroph - Fe2+ chemoheterotroph - glucose
photoautotroph - CO2
Cyanobacteria are a type of chemoautotroph. chemoheterotroph. photoautotroph. photoheterotroph.
photoautotroph.
Which of the following has bacteriochlorophylls and uses alcohols for carbon? chemoautotroph chemoheterotroph photoautotroph photoheterotroph
photoheterotroph
Which statements correspond to amphibolic pathways? 1. anabolic and catabolic reactions are joined through common intermediate 2. shared metabolic pathways 3. Feedback inhibition can help regulate rates of reactions 4. both types of reactions are necessary but do not occur simultaneously 2, 4 2, 3, 4 1, 2, 3, 4 1 only 1, 2, 3
1,2,3
Which of the following statements are TRUE? 1-Electron carriers are located at ribosomes. 2-ATP is a common intermediate between catabolic and anabolic pathways. 3-ATP is used for the long-term storage of energy and so is often found in storage granules. 4-Anaerobic organisms are capable of generating ATP via respiration. 5-ATP can be generated by the flow of protons across protein channels. 1, 3, 4 2, 4, 5 2, 3, 5 1, 2, 3 All of the statements are true.
2, 4, 5
Which energy-rich molecule directly powers cell work? Glucose ATP Water O2
ATP
What two molecules are produced by the light reactions and used to power the Calvin cycle? ATP and NADPH G3P and H2O CO2 and O2 C6H12O6 and RuBP C6H12O6 and O2
ATP and NADPH
Which of the following statements regarding the Entner-Doudoroff pathway is TRUE? It involves the pentose phosphate pathway. ATP is generated. NADH and ATP are generated. It involves glycolysis. NADH is generated.
ATP is generated.
Why is ATP required for glycolysis? ATP makes it easier to break apart glucose into two three-carbon molecules. ATP is used to reduce NAD+ to NADH. ATP is used to convert PEP into pyruvic acid. ATP is used to convert DHAP into G3P.
ATP makes it easier to break apart glucose into two three-carbon molecules.
What is the intermediate product formed by pyruvic acid during alcoholic fermentation? Formic acid Ethanol Lactic acid Carbon dioxide Acetaldehyde
Acetaldehyde
Which of the following is true of aerobic respiration compared to anaerobic respiration? Aerobic respiration is less efficient than all forms of anaerobic respiration, producing less ATP and larger end-products. Aerobic respiration uses oxygen as a final electron acceptor, whereas anaerobic respiration uses an inorganic molecule other than oxygen as the final electron acceptor. Aerobic respiration uses oxygen as a final electron acceptor, whereas anaerobic respiration uses an organic molecule. Aerobic respiration and anaerobic respiration both require oxygen as a final electron acceptor.
Aerobic respiration uses oxygen as a final electron acceptor, whereas anaerobic respiration uses an inorganic molecule other than oxygen as the final electron acceptor.
Where would you expect to find electron transport chains in a prokaryote? Along the inner mitochondrial membrane Along the outer mitochondrial membrane Along the plasma membrane Along the cell wall Free-floating in the cytoplasm
Along the plasma membrane
What connects the two photosystems in the light reactions? A thylakoid Chlorophyll An electron transport chain The Calvin cycle A chain of glucose molecules
An electron transport chain
The graph at the left in the figure shows the reaction rate for an enzyme at its optimum temperature. Which graph shows enzyme activity at a higher temperature? a b c d
B
Why does FADH2 yield less ATP than NADH? ADH2 electrons ultimately do not go to oxygen. Electrons from FADH2 cannot pump hydrogen ions out of the cell. FADH2 binds directly to the ATP synthase enzyme. FADH2 electrons enter the electron transport chain at a lower energy level.
FADH2 electrons enter the electron transport chain at a lower energy level.
T/F: Both respiration and photosynthesis use water molecules for the donation of hydrogen ions.
False
T/F: The pentose phosphate pathway can be characterized as an anabolic pathway.
False
T/F: The use of enzymes is necessary to increase the activation energy requirements of a chemical reaction.
False
Based on the animation, how many electron carriers are reduced in the Krebs cycle only? Four Five Three Six
Four
Which step is the step for which glycolysis is named? First Second Third Fourth Fifth Sixth
Fourth
What is the key product formed by the Calvin-Benson cycle? Carbon dioxide Water ATP Glucose and other sugars G3P
G3P
According to the animation, where would you find the lowest pH? In the cytochromes In the thylakoid space Outside the cell In the thylakoid membrane In the cytoplasm
In the thylakoid space
How is nevirapine used to treat HIV infections? It binds to the active site of HIV reverse transcriptase, decreasing that enzyme's activity. It alters the active site of reverse transcriptase, decreasing that enzyme's activity. It decreases the virus's ability to find host cells.It increases the immune system's ability to detect the virus.
It alters the active site of reverse transcriptase, decreasing that enzyme's activity.
Which of the following statements about anaerobic respiration is FALSE? It requires cytochromes. Only part of the Krebs cycle is utilized. It involves the reduction of an organic final electron acceptor.It generates ATP. It yields lower amounts of ATP when compared to aerobic respiration.
It involves the reduction of an organic final electron acceptor.It generates ATP.
Which of the following statements about fermentation is true? It provides additional protons to allow the electron transport chain to continue. It is an alternative way to return electron carriers to their oxidized state. It is an alternative way for a cell to produce oxygen. It allows the electron transport chain to continue in the absence of oxygen.
It is an alternative way to return electron carriers to their oxidized state.
What is the fate of pyruvic acid in an organism that uses aerobic respiration? It is catabolized in glycolysis. It reacts with oxaloacetate to form citrate.It is reduced to lactic acid. It is oxidized in the electron transport chain. It is converted into acetyl CoA.
It is converted into acetyl CoA.
What is the role of water in noncyclic photophosphorylation? It provides electrons and protons. It collects the electrons for the Calvin-Benson cycle. It harvests light energy. It directly generates ATP.
It provides electrons and protons.
Fatty acids are oxidized in the pentose phosphate pathway. the electron transport chain. the Krebs cycle. the Entner-Doudoroff pathway. glycolysis.
Krebs cycle
Which of the following statements is FALSE regarding the oxidation of proteins? Enzymes break down proteins into component amino acids. The amino group is removed through deamination and converted to nitrogenous waste, such as NH4+. Microbes produce extracellular enzymes to reduce proteins to their fatty acid and glycerol components so that each component can enter the Krebs cycle. After deamination of the protein, the organic acid enters the Krebs cycle.
Microbes produce extracellular enzymes to reduce proteins to their fatty acid and glycerol components so that each component can enter the Krebs cycle.
Which of the following can be used as a final electron acceptor for aerobic respiration? Nitrate ion, sulfate ion and carbonate ion can all be used as a final electron acceptor. Molecular oxygen Nitrate ion Sulfate ion Carbonate ion
Molecular oxygen
Which compound is being reduced in the reaction shown in the figure? NAD+ NADH NADH and isocitric acid isocitric acid and α-ketoglutaric acid α-ketoglutaric acid and NAD+
NAD+
Which one of the following would you predict is an allosteric inhibitor of the Krebs cycle enzyme, α-ketoglutarate dehydrogenase? NAD+ NADH α-ketoglutaric acidcitric acid ADP
NADH
Glycolysis produces energy in which form? NADH and ATP NADH ATP NADH, ATP, and pyruvic acid Pyruvic acid
NADH and ATP
According to the animation, which compounds provide electrons to the system? Oxygen NADH Water NADH and FADH2 FADH2
NADH and FADH2
What is the source of the electrons that reduce 1,3-bisphosphoglyceric acid? NADPH RuBP Sunlight G3P
NADPH
What transports electrons from the light reactions to the Calvin cycle? FADH2 An electron transport chain Chlorophyll NADPH NADH
NADPH
How many of the six G3P's produced in one cycle are used to make one molecule of glucose? Two Six Five One
One
Which of the following is needed as a reactant for the first step of the citric acid cycle? Oxaloacetic acid Succinyl CoA Malic acid Citric acid
Oxaloacetic acid
Which of the following is NOT necessary for respiration? flavoproteins oxygen quinones a source of electrons cytochromes
Oxygen
If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected? PABA will not be catalyzed. PABA products will increase in concentration. Sulfanilamide products will be in higher concentration. The substrate will destroy the inhibitor.
PABA will not be catalyzed.
What is the key difference between photoheterotrophs and photoautotrophs? Photoheterotrophs use hydrogen sulfide for reducing power; photoautotrophs do not. Photoheterotrophs produce oxygen as a by-product; photoautotrophs do not. Photoheterotrophs use organic compounds as their carbon source; photoautotrophs use carbon dioxide as their carbon source. Photoautotrophs only use bacteriochlorophyll; photoheterotrophs only use chlorophyll a.
Photoheterotrophs use organic compounds as their carbon source; photoautotrophs use carbon dioxide as their carbon source.
Compare and contrast three metabolic pathways by choosing whether the statement applies to anaerobic respiration.Check all that apply.
Process includes glycolysis The coenzyme NAD+ plays an important role in the pathway. Much or most of the ATP produced is produced by oxidative phosphorylation. Can generate ATP in the absence of O2. Between 2 and 38 ATP are produced per molecule of glucose input. Process involves electron transport and chemiosmosis Process involves the Krebs cycle
What is meant by substrate-level phosphorylation? Production of ATP using energy from a proton gradient Production of ATP by transferring phosphates directly from metabolic products to ADP Reduction of NAD+ to NADH Splitting of glucose into two pyruvic acid molecules
Production of ATP by transferring phosphates directly from metabolic products to ADP
What drives the production of ATP in cyclic photophosphorylation? Water splitting Oxygen generation Proton gradient NADPH
Proton gradient
How does the proton gradient help ATP synthase to make ATP? Protons are not involved with this step; only electrons are. Protons move from inside the membrane to outside the membrane. Protons move along the membrane. Protons move from outside the membrane to inside the membrane.
Protons move from outside the membrane to inside the membrane.
Which of the following types of organisms uses hydrogen sulfide for reducing power? Purple sulfur bacteria Algae Green nonsulfur bacteria Purple nonsulfur bacteria Cyanobacteria
Purple sulfur bacteria
What carbon molecules remain at the end of glycolysis? Glucose Pyruvic acid Dihydroxyacetone phosphate (DHAP) Glyceraldehyde 3-phosphate (G3P)
Pyruvic acid
Which of the following statements regarding redox reactions is true? Redox reactions involve an oxidation reaction coupled with a reduction reaction. Redox reactions are only seen in the electron transport chain. No metabolic reactions are redox reactions. Redox reactions must either be oxidizing reactions or reducing reactions.
Redox reactions involve an oxidation reaction coupled with a reduction reaction.
What is the fate of electrons in noncyclic photophosphorylation? Oxidize NADP+ to NADPH Reduce oxygen to water Reduce oxygen to carbon dioxide Oxidize oxygen to water Reduce NADP+ to NADPH
Reduce NADP+ to NADPH
Which of the following is true concerning ribozymes? Ribozymes would be affected by all the same factors that influence other enzymes. Ribozymes are protein molecules that behave as enzymes. Ribozymes act on a variety of substrates, such as sugar and proteins. Ribozymes have an active site and are not used up in chemical reactions.
Ribozymes have an active site and are not used up in chemical reactions.
Which step(s) of the Krebs cycle does (do) not produce any usable energy? The third step The second and seventh steps The sixth step The first and eighth steps The fifth step
The second and seventh steps
Which step involves the release of carbon dioxide? The third and fourth steps The second step The seventh step The first and eighth steps
The third and fourth steps
What is the fate of metabolites during respiration? They are rearranged to form GTP. They are oxidized completely to carbon dioxide and water. They are reduced to from NADH and FADH2. They are oxidized completely to form pyruvic acid.
They are oxidized completely to carbon dioxide and water.
What is the fate of the NADPH molecules created during noncyclic photophosphorylation? They bring electrons back to photosystem II. They are used to make ATP. They provide protons for the proton gradient. They are used in the Calvin-Benson cycle.
They are used in the Calvin-Benson cycle.
How does a competitive inhibitor slow enzyme catalysis? They bind to the substrate. They compete with the substrate for the enzyme's active site. They produce products toxic to the enzymes. They degrade the substrate.
They compete with the substrate for the enzyme's active site.
According to the animation, the reactions that occur between glucose and pyruvic acid can either be anabolic or catabolic. are neither catabolic nor anabolic. are only catabolic. are only anabolic.
can either be anabolic or catabolic.
The rates of O2 and glucose consumption by a bacterial culture are shown in the figure. Assume a bacterial culture was grown in a glucose medium without O2. Then O2 was added at the time marked X. The data indicate that these bacteria get more energy anaerobically. these bacteria don't use O2. aerobic metabolism is more efficient than fermentation. these bacteria cannot grow anaerobically.
aerobic metabolism is more efficient than fermentation.
Which of the following terms refers to pathways that can function both in anabolism and catabolism? amphibolic pathways homolactic fermentation pathways chemiosmotic pathways light-dependent pathways
amphibolic pathways
Researchers are developing a ribozyme that cleaves the HIV genome. This pharmaceutical agent could be described as a hydrolase. a genetic transposable element. a competitive inhibitor for reverse transcriptase. an RNA molecule capable of catalysis. a protease inhibitor.
an RNA molecule capable of catalysis.
A strictly fermentative bacterium produces energy by fermentation or aerobic respiration. by aerobic respiration only. only in the presence of oxygen. only in the absence of oxygen. by glycolysis only.
by glycolysis only.
Which of the following equations represents photosynthesis? 6CO2 + 6O2 → C6H12O6 + 6H2O C6H12O6 + 6CO2 → 6O2 + 6H2O 6CO2 + 6H2O → C6H12O6 + 6O2 6H2O + 6O2 → C6H12O6 + 6CO2 C6H12O6 + 6O2 → 6CO2 + 6H2O
6CO2 + 6H2O → C6H12O6 + 6O2
Which of the following is true of anabolic reactions? Anabolic reactions produce energy, which is used to convert ADP to ATP. Anabolic reactions use ATP and small substrates as building blocks to synthesize larger molecules. Anabolic and catabolic reactions both build complex organic molecules from simpler ones; however, anabolic reactions use ATP, whereas catabolic reactions transfer energy to create ATP. Anabolic reactions break down complex organic compounds into simpler ones.
Anabolic reactions use ATP and small substrates as building blocks to synthesize larger molecules.
Which biochemical process is NOT used during glycolysis? substrate-level phosphorylation beta oxidation carbohydrate catabolism oxidation-reduction enzymatic reactions
Beta oxidation
Which of the graphs in the figure best illustrates the activity of an enzyme that is saturated with substrate? a b c d e
C
What is the correct general equation for cellular respiration? C6H12O6 + 6CO2 → 6O2 + 6H2O + ATP energy 6CO2 + 6H2O + ATP energy → C6H12O6 + 6O2 C6H12O6 + 6H2O → 6CO2 + 6O2 + ATP energy 6O2 + 6H2O + ATP energy → C6H12O6 + 6CO2 C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP energy
Why might some cells uncouple the electron transport chain? Too much ATP is bad for the cell. Cells can use the energy from the proton gradient for functions other than producing ATP, such as heat generation. A cell does not require ATP. Uncoupling proteins offset the effect of cyanide.
Cells can use the energy from the proton gradient for functions other than producing ATP, such as heat generation.
Why do all enzymatic reactions need activation energy? Energy is required by an enzyme so that it can be reused. Energy is required to disrupt a substrate's stable electron configuration. Energy is needed for the enzyme to find its substrate.Energy allows only the substrate to bind.
Energy is required to disrupt a substrate's stable electron configuration.
Why are enzymes important to biological systems? Enzymes are reuseable. Enzymes prevent unwanted chemical by-products from forming. Enzymes decrease the amount of activation energy required for chemical reactions to occur. Enzymes increase the energy barrier required of chemical reactions.
Enzymes decrease the amount of activation energy required for chemical reactions to occur.
What is meant by the statement "Enzymes are biological catalysts"? Enzymes are products of biological systems. Enzymes produce biological organisms. Enzymes speed up the chemical reactions in living cells. Enzymes produce products useful for biology.
Enzymes speed up the chemical reactions in living cells.
Which of the following statements about photophosphorylation is FALSE? Light liberates an electron from chlorophyll. It occurs in photosynthesizing cells. Energy from oxidation reactions is used to generate ATP from ADP. It requires CO2. The oxidation of carrier molecules releases energy.
It requires CO2.
What provides electrons for the light reactions? H2O O2 CO2 Light The Calvin cycle
H2O
In green and purple bacteria, electrons to reduce CO2 can come from C6H12O6. H2S. CO2. chlorophyll. H2O.
H2S. (hydrogen sulfide)
What is the fate of the NAD+ newly regenerated by fermentation? It is converted into an organic acid. It is oxidized into carbon dioxide. It returns to glycolysis to pick up more electrons. It is converted into ethanol.
It returns to glycolysis to pick up more electrons.
What is the role of pyruvic acid in fermentation? It becomes the final electron acceptor for the electron transport chain in the absence of oxygen. It takes the electrons from NADH, oxidizing it back into NAD+. It provides the protons to be used in the electron transport chain. It is the organic acid end-product of fermentation.
It takes the electrons from NADH, oxidizing it back into NAD+.
How would a noncompetitive inhibitor interfere with a reaction involving the enzyme shown in the figure? It would bind to a. It would bind to b. It would bind to c. It would bind to d. The answer cannot be determined based on the information provided.
It would bind to b.
Iron is considered an essential element for many bacteria. Based on the animation, how would lack of iron affect energy production of a bacterium? Lack of iron would not have any affect on this system. Lack of iron would mean lack of heme, and thus lower amounts of functioning cytochrome proteins. This would mean lower energy yields. Lack of iron would mean that most of the oxygen could be reduced to form water, improving energy yields.
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? Pyruvic acid Lactic acid and propionic acid Propionic acid Lactic acid Ethanol
Lactic acid and propionic acid
Lipases break down proteins. nucleic acids. carbohydrates. lipids.
Lipids
A urease test is used to identify Mycobacterium tuberculosis because urease is a sign of tuberculosis. urea accumulates during tuberculosis. M. bovis can cause tuberculosis. some bacteria reduce nitrate ion. M. tuberculosis produces urease.
M. tuberculosis produces urease.
What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor? No change in enzyme activity would be observed. A decrease in the amount of inhibitor would be observed. A decrease in the concentration of enzyme would be observed. You would begin to see an increase in the enzyme's rate of activity.
No change in enzyme activity would be observed.
Assume you are working for a chemical company and are responsible for growing a yeast culture that produces ethanol. The yeasts are growing well on the maltose medium but are not producing alcohol. What is the most likely explanation? Not enough protein is provided. The maltose is toxic. O2 is in the medium. The temperature is too low. The temperature is too high.
O2 is in the medium.
Which of the following statements regarding the glycolysis pathway is FALSE? Four ATP molecules are generated via substrate-level phosphorylation. Two molecules of water are generated. Two NADH molecules are generated. Two pyruvate molecules are generated. One molecule of ATP is expended.
One molecule of ATP is expended.
What is the driving force of energy production in steps 6 and 7? The reduction of three-carbon compounds The reduction of NAD+ to NADH The energy potential of a proton gradient The oxidation of three-carbon compounds
The oxidation of three-carbon compounds
Which of the following is a trait unique to photosynthetic eukaryotes? The presence of thylakoid membranes The presence of chlorophyll a Using water for reducing power The presence of chloroplasts Living in aerobic environments
The presence of chloroplasts
T/F: Both respiration and photosynthesis require the use of an electron transport chain.
True
T/F: Carbon fixation occurs during the light-independent phase of photosynthesis.
True
T/F: Catabolic reactions are generally degradative and hydrolytic.
True
T/F: Glycolysis is utilized by cells in both respiration and fermentation.
True
T/F: In general, ATP is generated in catabolic pathways and expended in anabolic pathways.
True
T/F: Once an enzyme has converted substrates into products, the active site reverts back to its original form.
True
In the figure, the structure labeled "1" is a cell wall. ATP synthase. cytoplasm. NAD+. a plasma membrane.
a plasma membrane.
A reaction that involves the transfer of electrons from one molecule to another is referred to as a redox reaction. a reduction reaction. an oxidation reaction.
a redox reaction.