Glycolysis is an anaerobic process used to catabolize glucose. What does it mean for this process to be anaerobic?
(a) no oxygen is required
(b) no oxidation occurs
(c) it takes place in the lysosome
(d) glucose is broken down by the addition of electrons
a) no oxygen is required
Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP?
(a) the digestion of starch to glucose
(b) glycolysis
(c) the citric acid cycle
(d) oxidative phosphorylation
d. oxidative phosphorylation
The advantage to the cell of the gradual oxidation of glucose during cellular respiration compared with its combustion to CO2 and H2O in a single step is that ________________.
(a) more free energy is released for a given amount of glucose oxidized.
(b) n
c) energy can be extracted in usable amounts
Foods are broken down into simple molecular subunits for distribution and use throughout the body. Which type of simple subunits, listed below, is used preferentially as an energy source?
(a) simple sugars
(b) proteins
(c) free fatty acids
(d) glycerol
a) simple sugars
The final metabolite produced by glycolysis is ___________.
(a) acetyl CoA.
(b) pyruvate.
(c) 3-phosphoglycerate.
(d) glyceraldehyde 3-phosphate.
b) pyruvate
Glycolysis generates more stored energy than it expends. What is the net number of activated carrier molecules produced in this process (number and type of molecules produced minus the number of those molecules used as input)?
(a) 6 ATP, 2 NADH
(b) 4 ATP,
c) 2 ATP, 2 NADH
Which of the following steps or processes in aerobic respiration include the production of carbon dioxide?
(a) breakdown of glycogen
(b) glycolysis
(c) conversion of pyruvate to acetyl CoA
(d) oxidative phosphorylation
c) conversion of pyruvate to acetyl CoA
In step 4 of glycolysis, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to produce two three-carbon molecules (dihydroxyacetone phosphate and glyceraldehyde 3-phosphate). Which enzyme catalyzes this reaction?
(a) aldolase
(b) phosphoglucose iso
a) aldolase
The conversion of glyceraldehyde 3-phosphate to 1,3 bisphosphoglycerate in step 6 of glycolysis generates a "high energy" phosphoanhydride bond. Which of the following best describes what happens to that bond in step 7?
(a) It is hydrolyzed to drive the f
a) it is hydrolysis to drive the formation of ATP
Steps 7 and 10 of glycolysis result in substrate-level phosphorylation. Which of the following best describes this process?
(a) ATP is being hydrolyzed to phosphorylate the substrate.
(b) The energy derived from substrate oxidation is coupled to the conve
b) The energy is derived from substrate oxidation is coupled to the conversion of ADP to ATP
Several different classes of enzymes are needed for the catabolism of carbohydrates. Which of the following descriptions best matches the function of a kinase?
(a) An enzyme that catalyzes the rearrangement of bonds within a single molecule.
(b) An enzyme
d) An enzyme that catalyze the addition of phosphate groups to other molecules
Several different classes of enzymes are needed for the catabolism of carbohydrates. Which of the following descriptions best matches the function of an isomerase?
(a) An enzyme that catalyzes the rearrangement of bonds within a single molecule.
(b) An en
a) An enzyme that catalyze the rearrangement of bonds within a single molecule
Several different classes of enzymes are needed for the catabolism of carbohydrates. Which of the following descriptions best matches the function of a mutase?
(a) An enzyme that catalyzes the rearrangement of bonds within a single molecule.
(b) An enzyme
b) An enzyme that catalyze a change in the position of a specific chemical group within a single molecule
Several different classes of enzymes are needed for the catabolism of carbohydrates. Which of the following descriptions best matches the function of a dehydrogenase?
(a) An enzyme that catalyzes the rearrangement of bonds within a single molecule.
(b) An
c) An enzyme that catalyze the oxidation of a molecule by removing a hydride ion
On a diet consisting of nothing but protein, which of the following is the most likely outcome?
(a) loss of weight because amino acids cannot be used for the synthesis of fat
(b) muscle gain because the amino acids will go directly into building muscle
(c
d) excretion of more nitrogenous (ammonia-derived) wastes than with a more balance diet
Which of the following processes do not take place in the mitochondria?
(a) citric acid cycle
(b) conversion of pyruvate to activated acetyl groups
(c) oxidation of fatty acids to acetyl CoA
(d) glycogen breakdown
d) glycogen breakdown
Which reaction does the enzyme phosphoglucose isomerase catalyze?
(a) glucose glucose 6-phosphate
(b) fructose 6-phosphate fructose 1,6-bisphosphate
(c) glucose 6-phosphate fructose 6-phosphate
(d) glucose glucose 1-phosphate
c) glucose 6-phosphate fructose 6-phosphate
What purpose does the phosphorylation of glucose to glucose 6-phosphate by the enzyme hexokinase serve as the first step in glycolysis?
(a) It helps drive the uptake of glucose from outside the cell.
(b) It generates a high-energy phosphate bond.
(c) It c
a) It helps drive the uptake of glucose from outside the cell
Which of the following cells rely exclusively on glycolysis to supply them with ATP?
(a) anaerobically growing yeast
(b) aerobic bacteria
(c) skeletal muscle cells
(d) plant cells
a) anaerobically growing yeast
In anaerobic conditions, skeletal muscle produces _____________.
(a) lactate and CO2.
(b) ethanol and CO2.
(c) lactate only.
(d) ethanol only.
c) lactate only
Select the best option to fill in the blanks of the following statement: Fermentation is a/an _____________________ process that converts _____________ into carbon dioxide and _____________________.
(a) anaerobic, pyruvate, ethanol
(b) anaerobic, lactate,
a) anaerobic, pyruvate, ethanol
Glyceraldehyde 3-phosphate dehydrogenase operates by stripping a hydride ion from its substrate. Which molecule is the recipient of the proton and two electrons during this transfer?
(a) oxygen
(b) acetyl CoA
(c) NAD+
(d) FADH
c) NAD+
The first energy-generating steps in glycolysis begin when glyceraldehyde 3-phosphate undergoes an energetically favorable reaction in which it is simultaneously oxidized and phosphorylated by the enzyme glyceraldehyde 3-phosphate dehydrogenase to form 1,
b) The ?G� for the oxidation of the aldehyde group on glyceraldehyde 3-phosphate to form a carboxylic acid is more negative than the ?G� for ATP hydrolysis.
Pyruvate must move from the cytosol into the mitochondria, where it is oxidized to form CO2 and acetyl CoA by the pyruvate dehydrogenase complex. How many different enzymes and what total number of polypeptides, respectively, are required to perform this
d ) 3;60
The citric acid cycle is a critical sequence of reactions for energy production, which take place in the matrix of the mitochondria. The reaction cycle requires materials from the cytosol to be converted into acetyl CoA, which represents the starting poin
a) Amino acids can be converted to acetyl CoA
The reaction cycle that uses acetyl CoA to generate electron carrier molecules needed in the electron-transport chain is important for powering the cell. Which of the names below is not one of those commonly used to describe this reaction cycle?
(a) trica
c) oxaloacetic acid cycle
The citric acid cycle is a series of oxidation reactions that removes carbon atoms from substrates in the form of CO2. Where do the oxygen atoms in the carbon dioxide molecules come from?
(a) water
(b) phosphates
(c) molecular oxygen
(d) acetyl CoA
a) water
Fatty acids can easily be used to generate energy for the cell. Which of the following fatty acids will yield more energy? Explain your answer.
(a) CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH=CH-COOH
(b) CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH
(c) CH3-CH=CH-CH2-CH2-C
b) CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH
The citric acid cycle is a series of oxidation reactions that removes carbon atoms from substrates in the form of CO2. Once a molecule of acetyl CoA enters the citric acid cycle, how many complete cycles are required for both of the carbon atoms in its ac
d) 4
In step 1 of the citric acid cycle, citrate is generated by the enzyme citrate synthase. The enzyme combines the two-carbon acetyl group from acetyl CoA and the four-carbon oxaloacetate. What is the source of energy that drives this reaction forward?
(a)
c) a high-energy thioester bond
In step 2 of the citric acid cycle, the enzyme aconitase generates isocitrate from citrate. Which of the following statements about this reaction is true?
(a) There is a substantial free-energy difference between the reactants and products of this reactio
d) The reaction sequence first generates one molecule of water and then consumes one molecule of water.
In step 3 of the citric acid cycle, the oxidation of isocitrate and the production of CO2 are coupled to the reduction of NAD+, generating NADH and an ?-ketoglutarate molecule. In the isocitrate molecule shown in Figure Q13-47, which carbon is lost as CO2
d) 6 and 4
In step 4 of the citric acid cycle, the reduction of NAD+ to NADH is coupled to the generation of CO2 and the formation of a high-energy thioester bond. Which molecule provides the sulfhydryl group necessary to form the thioester bond?
(a) pyruvate
(b) ac
c) CoA
In step 4 of the citric acid cycle, the reduction of NAD+ to NADH is coupled to the generation of CO2 and the formation of a high-energy thioester bond. The energy of the thioester bond is harnessed in step 5. What is the energy used for?
(a) to generate
a) to generate a molecule of GTP
Step 6 of the citric acid cycle is catalyzed by succinate dehydrogenase. Keeping in mind that dehydrogenases catalyze redox reactions, which are the products of the reaction in which succinate is oxidized?
(a) fumarate, NADH
(b) fumarate, FADH2
(c) fumara
b) fumarate, FADH2
In the final step of the citric acid cycle, oxaloacetate is regenerated through the oxidation of malate and this is coupled with the production of which other molecule?
(a) FADH
(b) NADH
(c) GTP
(d) CO2
b) NADH
The oxygen-dependent reactions required for cellular respiration were originally thought to occur in a linear pathway. By using a competitive inhibitor for one enzyme in the pathway, investigators discovered that these reactions occur in a cycle. What com
a) Malonate
The oxygen-dependent reactions required for cellular respiration were originally thought to occur in a linear pathway. By using a competitive inhibitor for one enzyme in the pathway, investigators discovered that these reactions occur in a cycle. Which en
d) succinct dyhydrogenase
The oxygen-dependent reactions required for cellular respiration were originally thought to occur in a linear pathway. By using a competitive inhibitor for one enzyme in the pathway, investigators discovered that these reactions occur in a cycle. Which pr
b) malate
In the final stage of the oxidation of food molecules, a gradient of protons is formed across the inner mitochondrial membrane, which is normally impermeable to protons. If cells were exposed to an agent that causes the membrane to become freely permeable
a) The ratio of ATP to ADP in the cytoplasm would fall
Pyruvate is an important metabolic intermediate that can be converted into several other compounds, depending on which enzyme is catalyzing the reaction. Which of the following cannot be produced from pyruvate in a single enzyme-catalyzed reaction?
(a) la
c) citrate
When glucose is being used up and not replaced from food intake, the blood sugar level can be maintained by synthesizing glucose from smaller molecules such as pyruvate or lactate. This process is called gluconeogenesis. Which organ is principally respons
a) liver
Step 3 in glycolysis requires the activity of phosphofructokinase to convert fructose 6-phosphate into fructose 1,6-bisphosphate. Which of the following molecules is an allosteric inhibitor of this enzyme?
(a) Pi
(b) AMP
(c) ADP
(d) ATP
d) ATP
The conversion of fructose 1,6-bisphosphate to fructose 6-phosphate is catalyzed by a fructose 1,6-bisphosphatase and is one of the final steps in gluconeogenesis. Which of the following molecules is an allosteric activator of this enzyme?
(a) Pi
(b) AMP
d) ATP
Which of the following polymers of glucose is used as a vehicle to store energy reserves in animal cells?
(a) glucagon
(b) glycogen
(c) starch
(d) glycerol
b) glycogen
The intermediates of the citric acid cycle are constantly being depleted because they are used to produce many of the amino acids needed to make proteins. The enzyme pyruvate carboxylase converts pyruvate to oxaloacetate to replenish these intermediates.
c) fatty acids
Pyruvate can be converted into many other molecules by various biosynthetic and metabolic pathways, which makes it a central hub in the regulation of cellular metabolism. Which of the following molecules is not made from pyruvate?
(a) oxaloacetate
(b) eth
d) NADH
In humans, glycogen is a more useful food-storage molecule than fat because _____________________.
(a) a gram of glycogen produces more energy than a gram of fat.
(b) it can be utilized to produce ATP under anaerobic conditions, whereas fat cannot.
(c) it
b) it can be utilized to produce ATP under anaerobic conditions, whereas fat cannot
The concentration of H+ ions inside the mitochondrial matrix is lower than it is in the cytosol or the mitochondrial intermembrane space. What would be the immediate effect of a membrane-permeable compound that carries and releases protons into the mitoch
b) Inhibition of ATP synthesis