Biol 1001 Ch.8
Which of the following is the primary energy carrier for cells? - NADH - FADH2 - pyruvate - ATP - glucose - glycogen
ATP This energy carrier is used by almost all of the enzymes in a cell
For bacteria to continue growing rapidly when they shift from an aerobic environment to an anaerobic environment, they must: A. increase the rate of the electron transport chain. B. increase the rate of the Krebs cycle. C. increase the rate of glycolysis-based reactions.
C. increase the rate of glycolysis-based reactions.
What molecule is common to both C3 photosynthesis and the process of glycolysis? A. fructose B. G3P C. pyruvate
C. pyruvate
Which of these enters the citric acid cycle (also called the Krebs cycle)? - NADH + H+ - G3P - pyruvate - glucose - acetyl CoA
Acetyl CoA is a reactant in the citric acid cycle (also called the Krebs cycle).
Chemiosmosis in mitochondria directly results in the synthesis of: A. FADH2. B. ATP. C. H2O.
B. ATP.
Which of the following is a proper description of the path of hydrogen ions during the electron transport chain and chemiosmosis? A. Hydrogen ions from the matrix are pumped into the intermembrane space, then flow across the outer membrane through ATP synthase. B. Hydrogen ions from the matrix are pumped into the intermembrane space, then flow back into the matrix through ATP synthase.
B. Hydrogen ions from the matrix are pumped into the intermembrane space, then flow back into the matrix through ATP synthase.
The insecticide rotenone inhibits one of the steps of the electron transport system in mitochondria. What is a likely immediate result? A. The rate of the Krebs cycle reactions will increase. B. The rate of fermentation will increase. C. The transport of pyruvate into the mitochondria will increase.
B. The rate of fermentation will increase.
In fermentation _____ is reduced and _____ is oxidized. A. NADH ... lactate B. pyruvate ... NADH C. lactate ... NADH
B. pyruvate ... NADH
In the citric acid cycle, ATP molecules are produced by _____. A. photosynthesis B. substrate-level phosphorylation C. cellular respiration
B. substrate-level phosphorylation
All of the following are true statements about ATP EXCEPT that it is: A. the molecule that all living cells rely on to do work. B. synthesized only within mitochondria. C. the cell's principal compound for energy transfers.
B. synthesized only within mitochondria.
At the end of glycolysis, the original carbons of the glucose molecule form: A. two molecules of citric acid. B. two molecules of pyruvate. C. six molecules of carbon dioxide.
B. two molecules of pyruvate.
Why do cells convert the energy stored in the bonds of glucose into energy stored in the bonds of ATP? A. Cells can extract more energy from ATP than from glucose. B. Glycolysis and respiration convert sugar into ATP. C. Glucose is not a usable energy source for most enzymes.
C. Glucose is not a usable energy source for most enzymes.
Why is respiration a better method than fermentation for extracting energy from glucose? A. Fermentation produces no CO2 and H2O. B. Respiration uses up the NADH produced in glycolysis, producing more ATP. C. Respiration extracts energy from pyruvate that is wasted in fermentation.
C. Respiration extracts energy from pyruvate that is wasted in fermentation.
During which step of aerobic respiration is oxygen used? A. Krebs cycle B. fermentation C. electron transport system
C. electron transport system
Which of the following is common to both fermentation and cellular respiration? A. reduction of pyruvate to lactate B. Krebs cycle C. glycolysis
C. glycolysis
What reactants are necessary to create FADH2 during the Krebs cycle? - FAD, two electrons, and two H+ - FAD, four electrons, and two H+ - FAD2+, four electrons, and two H+ - FAD+, one electron, and H+ - FAD, two electrons, and H+ - FAD2+, two electrons, and two H+
FAD, two electrons, and two H+ Even though FAD makes two bonds, it still only uses two electrons. It donates two of its own to the bonds.
Why do cells convert the energy stored in the bonds of glucose into energy stored in the bonds of ATP? - Cells can extract more energy from ATP than from glucose. - Enzymes can burn ATP more efficiently than they can burn glucose. - Glucose is not a usable energy source for most enzymes. - Glycolysis and respiration convert sugar into ATP.
Glucose is not a usable energy source for most enzymes. The energy in the bonds of glucose can only be extracted by the enzymes of glycolysis and respiration. The rest of the cellular enzymes require energy in the form of an energy carrier, usually ATP.
What would happen if a cell converted all of its NAD+ into NADH? - Respiration would stop due to lack of electron carriers. - Energy is wasted by glycolysis as it can no longer store it in NADH. - Glycolysis would stop due to lack of a reactant. - Fermentation would replace glycolysis in generating ATP. - The cell would stop doing glycolysis because it has stored enough energy in NADH.
Glycolysis would stop due to lack of a reactant. Glycolysis requires NAD+. Storing electrons in the bonds of NADH is not an optional step
Which of the following is a proper description of the path of hydrogen ions during the electron transport chain and chemiosmosis? - Hydrogen ions from the matrix are pumped into the intermembrane space, then flow back into the matrix through ATP synthase. - Hydrogen ions from the intermembrane space are pumped into the matrix, then flow back into the intermembrane space through ATP synthase. - Hydrogen ions from the outer membrane are pumped into the intermembrane space, then flow into the matrix through ATP synthase. - Hydrogen ions from the matrix are pumped into the inner membrane, then flow into the intermembrane space through ATP synthase. - Hydrogen ions from the matrix are pumped into the intermembrane space, then flow across the outer membrane through ATP synthase. - Hydrogen ions from the intermembrane space are pumped into the inner membrane, then flow into the the matrix through ATP synthase.
Hydrogen ions from the matrix are pumped into the intermembrane space, then flow back into the matrix through ATP synthase. Hydrogen ions go back and forth between the matrix and the inner membrane space.
During electron transport, energy from _____ is used to pump hydrogen ions into the _____. - NADH and FADH2 ... mitochondrial matrix - NADH and FADH2 ... intermembrane space - NADH ... intermembrane space - acetyl CoA ... intermembrane space - NADH ... mitochondrial matrix
NADH and FADH2 ... intermembrane space The energy released as electrons, which have been donated by NADH and FADH2, is passed along the electron transport chain and used to pump hydrogen ions into the intermembrane space.
Why is respiration a better method than fermentation for extracting energy from glucose? - Respiration uses up the NADH produced in glycolysis, producing more ATP. - Fermentation produces no CO2 and H2O. - Fermentation uses up the NADH produced in glycolysis without producing any more ATP. - Fermentation produces a toxic by-product that must be broken down. - Respiration extracts energy from pyruvate that is wasted in fermentation.
Respiration extracts energy from pyruvate that is wasted in fermentation. Respiration results in 36 ATP per glucose molecule compared to the two ATP produced by glycolysis followed by fermentation.
Why is the Krebs cycle called a cycle? - The process begins in the cytoplasm, continues through the mitochondria, and returns to the cytoplasm. - The acetyl CoA used in the first step is immediately returned to the process of acetyl CoA formation. - The final product of the process serves as an initial reactant in the process. - The process consumes ATP and NADH, then produces both. - The process begins in the matrix of the mitochondria, continues through the intermembrane space, and returns to the matrix.
The final product of the process serves as an initial reactant in the process. Oxaloacetate is used as a reactant with acetyl CoA in the beginning and is regenerated at the end of the process.
Which statement describes the citric acid cycle? - This process joins 2 pyruvic acid molecules into a molecule of glucose. - 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 produces some ATP and carbon dioxide in the mitochondrion. - This process splits glucose in half and produces 2 ATPs for each glucose.
This process produces some ATP and carbon dioxide in the mitochondrion. The citric acid cycle breaks down carbon molecules, releasing carbon dioxide and forming some ATP.
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 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 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. In the electron transport chain, electrons move from one electron carrier to another, eventually reaching oxygen. The released energy is used to make ATPs.
What is the purpose of the electron transport chain? -to convert energy in electron carriers into ATP -to move high-energy electrons from electron carriers to H2O -To use energy from the passing of electrons in electron carriers into a high concentration of hydrogen ions -to move high-energy electrons from electron carriers to ATP
To use energy from the passing of electrons in electron carriers into a high concentration of hydrogen ions The gradient will later be used to generate ATP.
Where have the carbon atoms orignially present in glucose gone after the Krebs cycle has been completed? - One was lost in acetyl CoA formation and two were lost in the Krebs cycle. -Two were lost in acetyl CoA formation and four were lost in the Krebs cycle. -Three were lost during the Krebs cycle. -Six were lost during the Krebs cycle. -Two were lost in glycolysis, two were lost in acetyl CoA formation, and two were lost in the Krebs cycle. -One was lost in glycolysis, one was lost in acetyl CoA formation, and one was lost in the Krebs cycle.
Two were lost in acetyl CoA formation and four were lost in the Krebs cycle. The six carbon atoms of glucose are all CO2 by this point
What are the products of acetyl CoA formation from a molecule of pyruvate? - two acetyl CoA, two NADH, and two CO2 - NADH, CO2, and ATP - acetyl CoA and NADH - acetyl CoA, NADH, and CO2 - acetyl CoA, NAD+, and ATP
acetyl CoA, NADH, and CO2 These are the products of this reaction.
What is the net gain of energy carrier molecules from glycolysis, acetyl CoA formation, and the Krebs cycle? - four ATP, five NADH, and FADH2 - 34 ATP, 0 NADH, and 0 FADH2 - two ATP, 10 NADH, and FADH2 - four ATP, 10 NADH, and two FADH2 - six ATP, 10 NADH, and FADH2 - two ATP, five NADH, and FADH2
four ATP, 10 NADH, and two FADH2
Which of the following molecules is broken down in cellular respiration, providing fuel for the cell? - glucose - ATP - water - O2
glucose
Which of the following processes takes place in the cytosol of a eukaryotic cell? - ATP production by ATP synthase - acetyl CoA formation - citric acid cycle - glycolysis - electron transport chain
glycolysis Glycolysis, the breakdown of glucose into two molecules of pyruvic acid, takes place in the cytosol, outside the mitochondria.
ATP is produced with the help of the electron transport chain
how food molecules reach the body's cells and fuel cellular respiration. Step 4
In glycolysis, ATP molecules are produced by _____. - photophosphorylation - substrate-level phosphorylation - oxidative phosphorylation - photosynthesis - cellular respiration
substrate-level phosphorylation A phosphate group is transferred from glyceraldehyde phosphate to ADP.
In the citric acid cycle (also called the Krebs cycle), ATP molecules are produced by _____. - cellular respiration - substrate-level phosphorylation - oxidative phosphorylation - photophosphorylation - photosynthesis
substrate-level phosphorylation A phosphate group is transferred from GTP to ADP.
How many high-energy molecules are produced in one round of the Krebs cycle? - six NADH, two FADH2, and two ATP - three NADH, FADH2, and ATP - three NADH, FADH2, two ATP, and two CO2 - three NAD+, FAD, and ADP - three NADH, ATP, and two CO2
three NADH, FADH2, and ATP These molecules are produced from the consumption of one molecule of acetyl CoA
What is the purpose of fermentation? - to generate ATP without using-glycolysis - to generate ATP without using oxygen - to convert NADH back into NAD+ and FADH2 back into FAD - to extract energy from pyruvate - to convert NADH back into NAD+
to convert NADH back into NAD+ NAD+ is necessary to perform glycolysis.
How much usable energy is produced by lactic acid fermentation?
zero ATP and zero NADH Fermentation does not produce usable energy. It actually wastes the energy in NADH to return it to NAD+ for use by glycolysis.
In glycolysis, what starts the process of glucose breakdown? - ATP - Pyruvate - FADH2 - NADPH - ADP
ATP Some ATP energy is used to start the process of glucose oxidation.
For each glucose that enters glycolysis, _____ NADH enter the electron transport chain. - 2 - 6 - 10 - 0 - 4
10 For each glucose molecule that enters glycolosis, a total of 10 NADH are produced -- 2 are produced in glycolysis, 2 are produced in acetyl CoA production, and 6 are produced in the citric acid cycle.
In glycolysis there is a net gain of _____ ATP. - 1 - 3 - 2 - 4 - 5
2 It takes 2 ATP to produce 4 ATP.
How many NADH are produced by glycolysis? - 2 - 5 - 1 - 4 - 3
2 Two NADH molecules are produced by glycolysis.
The inner membrane of the mitochondria can be compared functionally to the thylakoid membranes of the chloroplast because both contain a system for: A. electron transport. B. pyruvate production. C. glucose synthesis.
A. electron transport.
If glucose is metabolized under completely anaerobic conditions, then pyruvate: A. is converted by fermentation to CO2 and ethanol or to lactate. B. is converted to NADH. C. immediately enters the Krebs cycle.
A. is converted by fermentation to CO2 and ethanol or to lactate.
As a bicyclist pedals up a hill to the finish line of a race and "feels the burn" in his leg muscles, those muscle cells are most likely utilizing: A. some lactate fermentation. B. only oxygen for maximum ATP production. C. only cellular respiration for maximum ATP production.
A. some lactate fermentation.
Which energy-rich molecule produced by cellular respiration directly powers cell work? - glucose - ATP - water - O2
ATP
The step in aerobic respiration that produces the most ATP per molecule of glucose is: A. glycolysis. B. chemiosmosis. C. the citric acid cycle.
B. chemiosmosis.
What is the correct general equation for cellular respiration? - C6H12O6 + 6 H2O → 6 CO2 + 6 O2 + ATP energy - 6 CO2 + 6 H2O + ATP energy → C6H12O6 + 6 O2 - 6 O2 + 6 H2O + ATP energy → C6H12O6 + 6 CO2 - C6H12O6 + 6 CO2 → 6 O2 + 6 H2O + ATP energy - C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy Cellular respiration extracts energy from glucose (C6H12O6) to produce smaller energy packets (ATP).
What reactants are always necessary to make NADH during the energy extraction reactions? A. NAD+, two electrons, and two H B. NAD+, one electron, and H+ C. NAD, two electrons, and H D. NAD+, two electrons, and H+
D. NAD+, two electrons, and H+
If photosynthesis and respiration are almost symmetrical processes, how is energy lost in the process of converting sugar back into ATP? - Energy is lost in water when O2 gets converted into H2O. - Energy is lost in the form of CO2. - Energy is lost as ATP during glycolysis. - Energy is lost as light during photosynthesis. - Energy is lost as heat during glycolysis and respiration.
Energy is lost as heat during glycolysis and respiration. Almost every chemical conversion you see in the processes of glycolysis and respiration has heat as a waste product.
Which of these is NOT a product of glycolysis? - water - FADH2 - pyruvate - ATP - NADH + H+
FADH2 FADH2 is a product of the citric acid cycle.
Imagine you could inject molecules into the leg muscles of a sprinter, right before a race. Which of the following would be most useful? - NAD+ - glycogen - glucose - NADH - FADH2 - FAD
NAD+ A large supply of NAD+ will allow the leg muscles to rapidly run glycolysis and avoid fermentation for a time.
What reactants are always necessary to make NADH during the energy extraction reactions? - NAD+, two electrons, and H+ - NADH, two electrons, and H+ - two NAD, two electrons, and two H - NAD, two electrons, and H - NAD+, two electrons, and two H - NAD+, one electron, and H+
NAD+, two electrons, and H+ These reactants are always used in the process of making NADH.
Where is the majority of the usable energy found at the completion of glycolysis, acetyl CoA formation, and the Krebs cycle? - NADH - CO2 - pyruvate - ATP - FADH2
NADH NADH is both a high-energy molecule and more numerous than any other product.
How many of the carbons originally present in acetyl CoA continue on to respiration after the Krebs cycle? - Three carbons are left as CO2. - Two carbons are left as NADH. - Two carbons are left as CO2. - No carbons are left, all are lost as CO2. - One carbon is left, two are lost as CO2.
No carbons are left, all are lost as CO2. The two carbons originally present in acetyl become two molecules of CO2.
What property of oxygen allows it to form bonds with the electrons found at the end of the electron transport chain? - Oxygen forms nonpolar, low-energy bonds. - Oxygen forms ionic, low-energy bonds. - Oxygen forms nonpolar, high-energy bonds. - Oxygen forms ionic, high-energy bonds. - Oxygen forms polar, low-energy bonds. - Oxygen forms polar, high-energy bonds.
Oxygen forms polar, low-energy bonds. Highly polar bonds can be formed from very low-energy electrons, like those found at the end of the electron transport chain.
Cyanide prevents oxygen from accepting electrons at the end of the electron transport chain. One of the first symptoms of cyanide poisoning is unconsciousness. Which of the following is a logical explanation for why the brain is affected by cyanide more than the rest of the body? - The brain runs out of oxygen before the rest of the body does. - Cyanide prevents oxygen from being used in the brain. - The brain runs out of glucose before the rest of the body does. - Cyanide prevents the brain from conducting respiration. - Cyanide prevents the brain from extracting energy from glucose. - The brain cannot use fermentation to continue glycolysis.
The brain cannot use fermentation to continue glycolysis. Because cyanide blocks the respiration pathway, cells must rely on glycolysis to generate ATP and fermentation to regenerate NAD+ for more glycolysis. The brain cannot use fermentation because the lactic acid produced would do too much damage.
Which of the following occurs immediately after a cell runs out of oxygen? - The fermentation reactions stop. - The fermentation reactions begin. - The Krebs cycle stops. - The electron transport chain stops. - The glycolysis reactions stop.
The electron transport chain stops. Oxygen is used at the end of the electron transport chain to remove used, low-energy electrons.
Where are the low-energy electrons located after the electron transport chain is completed? - They are recycled to earlier steps in the process. - They are added to H+ to form H. - They are located in the cytoplasm, where they contribute to the overall negative charge of the cell. - They are located in the bonds of H2O. - They are located in the bonds of ATP after chemiosmosis.
They are located in the bonds of H2O. Two electrons, two hydrogen ions, and an oxygen atom combine to form water.
Which statement describes glycolysis? - This process produces some ATP and carbon dioxide in the mitochondrion. - This process joins 2 pyruvic acid molecules into a molecule of glucose. - 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. - This process converts pyruvic acid to acetyl CoA.
This process splits glucose in half and produces 2 ATPs for each glucose. In glycolysis, glucose is split into two molecules of pyruvic acid. The released energy is stored in ATP and the electron carrier NADH.
What is the purpose of the electron transport chain? - to convert energy in electron carriers into ATP - to move high-energy electrons from electron carriers to H2O - to return NAD+ and FAD to the rest of the reactions of energy extraction - To use energy from the passing of electrons in electron carriers into a high concentration of hydrogen ions - to move high-energy electrons from electron carriers to ATP
To use energy from the passing of electrons in electron carriers into a high concentration of hydrogen ions
Which of these is NOT a product of the citric acid cycle (also called the Krebs cycle)? - CO2 - FADH2 - NADH + H+ - acetyl CoA - ATP
acetyl CoA Acetyl CoA enters the citric acid cycle.
Why don't we use bacteria that perform lactic acid fermentation to make bread? - because the bacteria would infect people who ate the bread - because lactic acid is a poison that must be broken down by the liver - because the bacteria would cause the dough to spoil - because yeast use alcohol fermentation - because lactic acid does not taste good - because lactic acid fermentation doesn't produce a gas
because lactic acid fermentation doesn't produce a gas Ethanol fermentation from yeast produces CO2 gas, which causes the bread to rise.
A line of mutated yeast cells, called Wee mutants, has no mitochondria. Their name comes from the fact that these cells are very small compared to other yeast cells. Which energy-harvesting processes can Wee mutants perform? - glycolysis, fermentation, and respiration - glycolysis and fermentation - cellular respiration - glycolysis - the aerobic processes
glycolysis and fermentation These processes occur in the cytoplasm.
Select the correct sequence of steps as energy is extracted from glucose during cellular respiration. - acetyl CoA → citric acid cycle → electron transport chain → glycolysis - glycolysis → citric acid cycle → acetyl CoA → electron transport chain - glycolysis → acetyl CoA → citric acid cycle → electron transport chain - citric acid cycle → electron transport chain → glycolysis → acetyl CoA - electron transport chain → citric acid cycle → glycolysis → acetyl CoA
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.
What does NADH contain that is useful to a cell? - high-energy electrons - oxygen ion - hydrogen ion - high-energy phosphate - nothing, NADH is a waste product
high-energy electrons The high-energy electrons in NADH can be used by the reactions of respiration.
Eating food provides fuel and building blocks for your body
how food molecules reach the body's cells and fuel cellular respiration. Step 1
After food is broken down in the digestive system, it transported to cells via the circulatory system
how food molecules reach the body's cells and fuel cellular respiration. Step 2
Fuel molecules are broken down further in glycolysis and the ctric acid cycle (Krebs cycle)
how food molecules reach the body's cells and fuel cellular respiration. Step 3
The proximate (immediate) source of energy for oxidative phosphorylation is _____. - ATP - ATP synthase - substrate-level phosphorylation - kinetic energy that is released as hydrogen ions diffuse down their concentration gradient - NADH and FADH2
kinetic energy that is released as hydrogen ions diffuse down their concentration gradient Concentration gradients are a form of potential energy.
In muscle cells, fermentation produces _____. - carbon dioxide, ethanol, NAD+, and ATP - lactate and NADH - pyruvate - lactate and NAD+ - carbon dioxide, ethanol, NADH, and ATP
lactate and NAD+ These are the products of fermentation as it occurs in muscle cells.
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain? - Golgi apparatus - mitochondrion - chloroplast - nucleus - lysosome
mitochondrion All of the steps of cellular respiration except glycolysis take place in the mitochondrion.
In cellular respiration, most ATP molecules are produced by _____. - substrate-level phosphorylation - cellular respiration - photosynthesis - photophosphorylation - oxidative phosphorylation
oxidative phosphorylation This process utilizes energy released by electron transport.
The final electron acceptor of cellular respiration is _____. - water - oxygen - FADH2 - CO2 - NADH
oxygen Oxygen is combined with electrons and hydrogen to form water.
What are the net products of glycolysis? - four ATP, NADH, two pyruvate, and six CO2 - two ATP, two NADH, and six CO2 - four ATP, two NADH, and two pyruvate - two ATP, two NADH, and two pyruvate - four ATP, NADH, two pyruvate, and two CO2
two ATP, two NADH, and two pyruvate The reaction produces four ATP, two NADH, and two pyruvate, but two ATP were used to provide activation energy
Which of the following uses alcohol fermentation in the absence of oxygen? - yeast - bacteria in yogurt - humans - dogs - bacteria in cheese
yeast Yeast are used to ferment many fruit and grain products into alcohol.
