Exam 3 Study Questions
Which is an example of chemical to mechanical energy conversion that occurs in living organisms? a) ATP-driven muscle contraction b) ATP-dependent photon emission in fireflies c) light-induced electron flow in chloroplasts d) ATP-driven active transport across a membrane
a) ATP-driven muscle contraction (Explanation: ATP-dependent photon emission in fireflies is an example for chemical to electromagnetic energy conversion. Light-induced electron flow in chloroplasts is an example for electromagnetic to electrical energy conversion. ATP-driven active transport across a membrane is an example for chemical to osmotic energy conversion.)
Which of the following type of metabolites is used for generating glucose under severe starvation conditions? a) Amino acids b) Fats c) Glycogen d) Starch
a) Amino acids (Explanation: Fats cannot be converted to glucose; there is no store of carbohydrate. Only amino acids can be used for generating glucose under severe starvation conditions.)
Hydrolysis of lactose yields ___________ a) D-galactose and D-glucose b) D-glucose and D-glucose c) D-galactose and D-fructose d) D-fructose and D-glucose
a) D-galactose and D-glucose (Explanation: Hydrolysis of lactose yields D-galactose and D-glucose.)
What are the end products in ethanol fermentation? a) Ethanol and CO2 b) Ethanol and O2 c) Ethanol, H2 and CO2 d) Ethanol, O2 and CO2
a) Ethanol and CO2
Which of the following is a potent regulator of glycolysis and gluconeogenesis? a) Fructose 2, 6-bisphosphate b) Fructose 1, 6-bisphosphate c) Fructose 6-phosphate d) Glucose 1, 6-bisphosphate
a) Fructose 2, 6-bisphosphate (Explanation: The hormonal regulation of glycolysis and gluconeogenesis is mediated by fructose 2, 6-bisphosphate.)
Which product is formed in the isomerization of mannose 6-phosphate? a) Fructose 6-phosphate b) Glucose 6-phosphate c) 2-phosphoglycerate d) 3-phosphoglycerate
a) Fructose 6-phosphate (Explanation: Mannose 6-phosphate is isomerized by phosphomannose isomerase to yield fructose 6-phosphate.)
The deficiency of which of the following enzyme leads to galactosemia? a) Galactokinase b) Pyruvate kinase c) PFK-1 d) PFK-2
a) Galactokinase (Explanation: In galactokinase deficiency galactosemia, high galactose concentrations are found in blood and urine.)
The conversion of which of the following involves two nucleotide derivatives? a) Galactose 1-phosphate to glucose 1-phosphate b) Galactose 1-phosphate to fructose 1-phosphate c) Fructose 1-phosphate to glucose 1-phosphate d) Lactose 1-phosphate to glucose 1-phosphate
a) Galactose 1-phosphate to glucose 1-phosphate (Explanation: The conversion of galactose 1-phosphate to glucose 1-phosphate involves two nucleotide derivatives: UDP-galactose and UDP-glucose.)
Which of the following is involved in pentose phosphate pathway? a) Glucose 6-phosphate dehydrogenase b) Acyl co-A glycerol transferases c) PFK-2/FBPase-2 d) Pyruvate dehydrogenase
a) Glucose 6-phosphate dehydrogenase (Explanation: Acyl co-A glycerol transferases involved in triacylglycerol synthesis, pyruvate dehydrogenase involved in fatty acid synthesis.)
NADP-linked dehydrogenase catalyzes _________ a) Glucose 6-phosphate+NADP+ ↔ 6-phosphogluconate + NADPH + H+ b) Lactate + NAD+ ↔ pyruvate + NADH + H+ c) Pyruvate + CoA + NAD+ ↔ acetyl-CoA + CO2 + NADH + H+ d) L-Malate + NAD+ ↔ oxaloacetate + NADH + H+
a) Glucose 6-phosphate+NADP+ ↔ 6-phosphogluconate + NADPH + H+
Glycolysis converts ___________ a) Glucose into pyruvate b) Glucose into phosphoenolpyruvate c) Fructose into pyruvate d) Fructose into phosphoenolpyruvate
a) Glucose into pyruvate (Explanation: Glycolysis is a metabolic pathway that converts glucose into pyruvate.)
When one molecule of glucose is oxidized to two molecules of lactate during anaerobic glycolysis, which of the following statements is false? a) Glyceraldehyde 3-P dehydrogenase reaction produces 2 ATP molecules b) Lactate dehydrogenase reaction produces no ATP c) Pyruvate kinase reaction produces 2 ATP molecules d) Phosphofructokinase-1 reaction uses 1 ATP molecule
a) Glyceraldehyde 3-P dehydrogenase reaction produces 2 ATP molecules
Dihydroxyacetone phosphate is rapidly and reversibly converted to ___________ a) Glyceraldehyde 3-phosphate b) 1, 3-bis-phosphoglycerate c) Fructose 1, 6-bisphosphate d) Fructose 6-phosphate
a) Glyceraldehyde 3-phosphate (Dihydroxyacetone phosphate is rapidly and reversibly converted to glyceraldehyde 3-phosphate by triose phosphate isomerase.)
High concentration of glucose 6-phosphate is inhibitory to ___________ a) Hexokinase b) Pyruvate kinase c) Glucokinase d) Phosphofructokinase-1
a) Hexokinase (Explanation: Hexokinase catalyzes the reaction involving conversion of glucose to glucose 6-phosphate.)
Which of the following enzyme catalyzes the first step of glycolysis? a) Hexokinase b) Pyruvate kinase c) Glucokinase d) Phosphofructokinase-1
a) Hexokinase (Explanation: The first of glycolysis is irreversible under intracellular conditions and is catalyzed by hexokinase.)
Gluconeogenesis responds to which of the following? a) Hormonal control b) pH control c) Temperature control d) Blood control
a) Hormonal control (Explanation: When the blood glucose level decreases, the hormone glucagon signals the liver to produce and release more glucose and to stop consuming it for its own needs. One source of glucose is gluconeogenesis.)
Diminished delivery of oxygen to tissues is termed as ___________ a) Hypoxia b) Ischemia c) Homeostasis d) Metabolism
a) Hypoxia (Explanation: Diminished delivery of oxygen to tissues is termed as hypoxia.)
What are the effects of increased concentration of citrate? a) Increases the inhibitory effect of ATP b) Decreases the inhibitory effect of ATP c) Increases the activity of ATP d) Increases the activity of AMP
a) Increases the inhibitory effect of ATP (Explanation: Citrate is a key intermediate in the aerobic oxidation of pyruvate, fatty acids and amino acids. It serves as an allosteric regulator of PFK-1; its high concentration increases the inhibitory effect of ATP, further reducing the flow of glucose through glycolysis.)
Which of the following statements is true about the control of muscle glycogen phosphorylase? a) It is activated by phosphorylation by an active phosphorylase kinase b) It is allosterically activated by ATP c) It is allosterically activated by cAMP d) Normally it exists in active form
a) It is activated by phosphorylation by an active phosphorylase kinase (Explanation: It is allosterically inhibited by ATP. It is partially activated allosterically by AMP. Normally it exists in inactive form.)
Which of the following statements is true about PFK-1? a) It is stimulated by AMP and ADP b) It is stimulated by citrate and ATP c) It is inhibited by AMP and ADP d) It is stimulated by citrate and ADP
a) It is stimulated by AMP and ADP (Explanation: AMP promotes glycogen degradation and glycolysis by activating glycogen phosphorylase and stimulating the activity of phosphofructokinase-1. ATP and citrate are allosteric inhibitors.)
Which of the following is true about the enzyme producing NADH from a triose phosphate in the glycolytic pathway? a) It produces 1, 3-biphosphoglycerate and NADH b) It catalyzes irreversible reaction c) It uses NAD+ and dihydroxyacetone phosphate as substrates d) It uses FADH2 and glyceraldehyde 3-phosphate as substrates
a) It produces 1, 3-biphosphoglycerate and NADH (Explanation: Triose phosphate, glyceraldehyde 3-phosphate is oxidized to 1, 3-biphosphoglycerate in the presence of dehydrogenase enzyme.)
Glucose 6-phosphatase is present only in ___________ a) Liver b) Muscle c) Epithelial tissues d) Kidneys
a) Liver (Explanation: Glucose 6-phosphatase which hydrolyzes glucose 6-phosphate is present only in liver. Other tissues lack glucose 6-phosphatase.)
For its activity, pyruvate decarboxylase requires ______________ a) Mg+2 b) Ca+2 c) Na+ d) H+
a) Mg+2 (Explanation: Pyruvate decarboxylase requires Mg+2 in the conversion of pyruvate to acetaldehyde.)
Which out of the following statements is true about the regulation of metabolic pathway? a) Most of the metabolic pathways are regulated b) Most of the metabolic pathways are not regulated c) Regulation of metabolic pathways always involves changing the amount of enzymes d) Metabolic regulation always depends on control by hormones
a) Most of the metabolic pathways are regulated (Explanation: According to the physiological needs, rate of metabolism needs to be changed.)
In mitochondria, hydride ions are removed from substrates by _________ a) NAD-linked dehydrogenases b) NADP-linked dehydrogenases c) ATP synthase d) Succinate dehydrogenases
a) NAD-linked dehydrogenases
Complex 1 is also called _________ a) NADH dehydrogenase b) Succinate dehydrogenase c) Cytochrome bc1 complex d) Cytochrome oxidase
a) NADH dehydrogenase
Glycogen synthase a is activated by ___________ a) Phosphorylation catalyzed by GSK3 b) Dephosphorylation catalyzed by GSK3 c) Phosphorylation catalyzed by pyruvate kinase d) Phosphorylation catalyzed by pyruvate carboxylase
a) Phosphorylation catalyzed by GSK3 (Explanation: A protein kinase (PDK-1) that is activated when bound to PIP3 activates a second protein kinase (PKB) which phosphorylates glycogen synthase kinase 3 (GSK-3). The inactivation of GSK3 allows PP1 to dephosphorylate glycogen synthase converting it to its active form.
Which one of the following statements about the control of enzyme activity by phosphorylation is correct? a) Phosphorylation of an enzyme results in a conformational change b) Phosphorylation of an enzyme occurs only at specific tyrosine residues c) Phosphorylation of an enzyme is carried out by phosphoprotein phosphatases d) Enzyme control by phosphorylation is irreversible
a) Phosphorylation of an enzyme results in a conformational change (Explanation: Phosphorylation of enzyme is reversible; phosphorylation is not carried out by phosphoprotein phosphatases.)
The only membrane bound enzyme in the citric acid cycle is _________ a) Succinate dehydrogenase b) NADH dehydrogenase c) ATP synthase d) Acyl co-A dehydrogenase
a) Succinate dehydrogenase (Explanation: The only membrane bound enzyme in the citric acid cycle is succinate dehydrogenase.)
Which of the following statements is true about brain metabolism in starvation? a) The brain can use glucogenic amino acids for energy b) The brain can only use glucose as fuel c) Up to a quarter of energy requirement of the brain can come from fatty acids d) Up to a half of energy requirement of the brain can come from ketone bodies
a) The brain can use glucogenic amino acids for energy (Explanation: Brain does not use amino acids directly but glucose derived from glucogenic amino acids in the liver.)
A lipid-soluble benzoquinone with a long isoprenoid side chain is? a) Ubiquinone b) Cytochrome b c) Cytochrome c d) Cytochrome a
a) Ubiquinone (Explanation: Ubiquinone also known as coenzyme Q is a lipid-soluble benzoquinone with a long isoprenoid side chain.)
When glucose is converted to lactate by anaerobic glycolysis, equivalent number of ATPs derived is? a) 1 b) 2 c) 3 d) 4
b) 2
Maltose hydrolysis yields ___________ a) D-galactose and D-glucose b) 2-D-glucose c) n-D-glucose d) 2-D-fructose
b) 2-D-glucose (Explanation: Maltose hydrolysis yields 2-D-glucose.)
How many steps are catalyzed by different enzymes in glycolysis and gluconeogenesis? a) 2 b) 3 c) 4 d) 5
b) 3 (Explanation: Hexokinase, phosphofructokinase-1 and pyruvate kinase in glycolysis, Glucose 6-phosphatase, fructose 1, 6-bisphosphatase, PEP carboxykinase and pyruvate carboxylase in gluconeogenesis.)
The product formed in the first substrate level phosphorylation in glycolysis is ___________ a) Pyruvate b) 3-phosphoglycerate c) 1, 3-bisphosphoglycerate d) 2-phosphoglycerate
b) 3-phosphoglycerate (Explanation: Phosphoglycerate kinase transfers phosphoryl group from 1, 3-bisphosphoglycerate to ADP forming ATP and 3-phosphoglycerate.)
How many steps are catalyzed by the same enzymes in both glycolysis and gluconeogenesis? a) 6 b) 7 c) 8 d) 9
b) 7 (Explanation: Phosphohexose isomerase, aldolase, triose phosphate isomerase, glyceraldehyde phosphate dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase and enolase are the enzymes which catalyze the reactions in both glycolysis and gluconeogenesis.)
Anabolism and catabolism are chemically linked in the form of __________ a) ADP b) ATP c) Phosphodiester linkage d) ASP
b) ATP (Explanation: Anabolism is an energy intake process where small molecules build up to large molecules whereas catabolism involves the release of energy where large molecules tear down to smaller molecules.)
Which is an example of chemical to electromagnetic energy conversion that occurs in living organisms? a) ATP-driven muscle contraction b) ATP-dependent photon emission in fireflies c) light-induced electron flow in chloroplasts d) ATP-driven active transport across a membrane
b) ATP-dependent photon emission in fireflies (Explanation: ATP-driven muscle contraction is an example for chemical to mechanical energy conversion. Light-induced electron flow in chloroplasts is an example for electromagnetic to electrical energy conversion. ATP-driven active transport across a membrane is an example for chemical to osmotic energy conversion.)
Which of the following is involved in triacylglycerol synthesis? a) Hexokinase II b) Acyl co-A glycerol transferases c) PFK-2/FBPase-2 d) Pyruvate dehydrogenase
b) Acyl co-A glycerol transferases (Explanation: Hexokinase II involved in glycolysis, pyruvate dehydrogenase involved in fatty acid synthesis.)
Which of the following enzyme is present in saliva? a) Hexokinase b) Alpha amylase c) Fructokinase d) Triose kinase
b) Alpha amylase (Explanation: Digestion begins in the mouth, where salivary alpha amylase hydrolyses starch to sucrose.)
Glucagon and epinephrine stimulate glycogen breakdown to glucose 6-phosphate ________ a) Directly by binding to glycogen phosphorylase b) Indirectly by first stimulating adenylate cyclase to make cAMP c) Only in the liver d) Only in muscle cells
b) Indirectly by first stimulating adenylate cyclase to make cAMP (Explanation: The second messenger cAMP increases in concentration in response to stimulation by epinephrine in muscle or glucagon in liver.)
The phosphate groups used during glycolysis are ____________ a) Organic b) Inorganic c) Neutral d) None
b) Inorganic
Diminished flow of blood to tissues is termed as ___________ a) Hypoxia b) Ischemia c) Homeostasis d) Metabolism
b) Ischemia (Explanation: Diminished flow of blood to tissues is termed as ischemia.)
Which of the following statements is true regarding acetyl co-A? a) It stimulates pyruvate dehydrogenase b) It stimulates pyruvate carboxylase c) It inhibits pyruvate carboxylase d) It stimulates hexokinase
b) It stimulates pyruvate carboxylase (Explanation: Gluconeogenesis is regulated at the level of pyruvate carboxylase which is activated by acetyl co-A.)
What is the first step in the payoff phase of glycolysis? a) Reduction of 1, 3-bisphosphoglycerate to glyceraldehyde 3-phosphate b) Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate c) Reversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate d) Irreversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
b) Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate (Explanation: Glyceraldehyde 3-phosphate dehydrogenase catalyzes the first step in the payoff phase, oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate.)
Glucagon is released from ___________ a) Muscle b) Pancreas c) Kidneys d) Epithelial tissues
b) Pancreas (Explanation: Glucagon is released from pancreas and causes the liver to convert glycogen to glucose.)
Phosphoryl groups are derivatives of ____________ a) Phosphorous acid b) Phosphoric acid c) Acetic acid d) Citric acid
b) Phosphoric acid
Which enzyme is involved in the pathway of ethanol fermentation? a) Hexokinase b) Pyruvate decarboxylase c) Pyruvate dehydrogenase d) Pyruvate kinase
b) Pyruvate decarboxylase
Complex 2 is also called _________ a) NADH dehydrogenase b) Succinate dehydrogenase c) Cytochrome bc1 complex d) Cytochrome oxidase
b) Succinate dehydrogenase
TPP (thiamine pyrophosphate) is derived from ____________ a) Vitamin A b) Vitamin B1 c) Vitamin C d) Vitamin B2
b) Vitamin B1
Cleavage of Fructose 1, 6-biophosphate yields ___________ a) Two aldoses b) Two ketoses c) An aldose and a ketose d) Only a ketose
c) An aldose and a ketose (Explanation: Fructose 1, 6-biophosphate is cleaved to yield glyceraldehyde 3-phosphate, an aldehyde and dihydroxyacetone phosphate, a ketose.)
Complex 3 is also called _________ a) NADH dehydrogenase b) Succinate dehydrogenase c) Cytochrome bc1 complex d) Cytochrome oxidase
c) Cytochrome bc1 complex
The second control point in gluconeogenesis is the reaction catalyzed by ___________ a) Pyruvate kinase b) Pyruvate dehydrogenase c) FBPase-1 d) PFK-1
c) FBPase-1 (Explanation: The second control point in gluconeogenesis is the reaction catalyzed by fructose 1, 6-bisphosphatase-1.)
What is the general term used for the anaerobic degradation of glucose to obtain energy? a) Anabolism b) Oxidation c) Fermentation d) Metabolism
c) Fermentation (Explanation: Fermentation is the general term used for the degradation of glucose to obtain energy in the form of ATP.)
Protein that contains a nucleic acid derivative of riboflavin is called _________ a) Nucleic acid b) Amino acid c) Flavoprotein d) None
c) Flavoprotein (Explanation: Flavoproteins contain a very tightly, sometimes covalently, bound flavin nucleotide, either FMN or FAD.)
Water does a nucleophilic attack on phosphate monoester by producing ____________ a) Phosphorous chloride b) Phosphorous sulfide c) Inorganic phosphate d) Organic phosphate
c) Inorganic phosphate (Explanation: Inorganic phosphate is produced when a nucleophilic attack is done by water on phosphate monoester.)
Which of the following is false about acetyl-coA? a) It is a thioester b) It has a large, negative standard free energy of hydrolysis c) It contains phosphorous atom in the position occupied by an oxygen atom in oxygen esters d) It contains a sulfur atom in the position occupied by an oxygen tom in oxygen esters
c) It contains phosphorous atom in the position occupied by an oxygen atom in oxygen esters (Explanation: Acetyl-coA is a thioester containing phosphorous atom in the position occupied by an oxygen atom in oxygen esters.)
In the reduction of pyruvate to lactate, which of the following is regenerated? a) H+ b) NADH c) NAD+ d) Na+
c) NAD+ (Explanation: NAD+ is regenerated from NADH by the reduction of pyruvate to lactate.)
Which is the major factor(s) determining whether glucose is oxidized by aerobic or anaerobic glycolysis? a) Ca+2 b) FADH2 c) NADH and the ATP/ADP ratio d) Presence of high AMP
c) NADH and the ATP/ADP ratio (Explanation: NADH and the ATP/ADP ratio are the major factors determining whether glucose is oxidized by aerobic or by anaerobic glycolysis.)
Which of the following enzyme's gene expression is slowed by insulin? a) Hexokinase II b) Hexokinase IV c) PEP carboxykinase d) Pyruvate kinase
c) PEP carboxykinase (Explanation: Insulin stimulates the transcription of the genes that encode hexokinase II, hexokinase IV and pyruvate kinase.)
Which of the following enzymes is involved in the positive regulation of glycolysis/gluconeogenesis? a) Hexokinase II b) Hexokinase IV c) PFK-2/FBPase-2 d) Pyruvate kinase
c) PFK-2/FBPase-2 (Explanation: Increased expression of PFK-2/FBPase-2 regulates glycolysis/gluconeogenesis.)
Which substrate is used in the last step of glycolysis? a) Glyceraldehyde 3-phosphate b) Pyruvate c) Phosphoenolpyruvate d) 1, 3-bisphosphoglycerate
c) Phosphoenolpyruvate (Explanation: The last step in glycolysis is the transfer of phosphoryl group from phosphoenolpyruvate to ADP catalyzed by pyruvate kinase.)
Which of the following enzyme is responsible for the conversion of glucose 1-phosphate to glucose 6-phosphate? a) Glycogen phosphorylase b) Isomerase c) Phosphoglucomutase d) Epimerase
c) Phosphoglucomutase (Explanation: Phosphoglucomutase converts the glucose 1-phosphate to glucose 6-phosphate, which can enter glycolysis.)
Which enzyme is involved in the pathway of synthesis of acetyl-coA? a) Hexokinase b) Pyruvate decarboxylase c) Pyruvate dehydrogenase d) Pyruvate kinase
c) Pyruvate dehydrogenase
An exergonic reaction ____________ a) Proceeds spontaneously b) Does not require activation energy c) Releases energy d) Requires energy
c) Releases energy
The rate of breakdown of metabolites is termed as ___________ a) Metabolic state b) Metabolism c) Steady state d) Homeostasis
c) Steady state (Explanation: The rate of breakdown of metabolites is termed as a steady state.)
Which is an example of electromagnetic to electrical energy conversion that occurs in living organisms? a) ATP-driven muscle contraction b) ATP-dependent photon emission in fireflies c) light-induced electron flow in chloroplasts d) ATP-driven active transport across a membrane
c) light-induced electron flow in chloroplasts (Explanation: ATP-driven muscle contraction is an example for chemical to mechanical energy conversion. ATP-dependent photon emission in fireflies is an example for chemical to electromagnetic energy conversion. ATP-driven active transport across a membrane is an example for chemical to osmotic energy conversion.)
Dextrin hydrolysis yields ___________ a) D-galactose and D-glucose b) 2-D-glucose c) n-D-glucose d) 2-D-fructose
c) n-D-glucose (Explanation: Dextrin hydrolysis yields n-D-glucose.)
Which is an example of chemical to osmotic energy conversion that occurs in living organisms? a) ATP-driven muscle contraction b) ATP-dependent photon emission in fireflies c) light-induced electron flow in chloroplasts d) ATP-driven active transport across a membrane
d) ATP-driven active transport across a membrane (Explanation: ATP-driven muscle contraction is an example for chemical to mechanical energy conversion. ATP-dependent photon emission in fireflies is an example for chemical to electromagnetic energy conversion. Light-induced electron flow in chloroplasts is an example for electromagnetic to electrical energy conversion.)
The first step in the β oxidation of fatty acyl co-A is catalyzed by _________ a) Succinate dehydrogenase b) NADH dehydrogenase c) ATP synthase d) Acyl co-A dehydrogenase
d) Acyl co-A dehydrogenase (Explanation: It involves the transfer of electrons from the substrate to the FAD of the dehydrogenase, then to ETF.)
Complex 4 is also called _________ a) NADH dehydrogenase b) Succinate dehydrogenase c) Cytochrome bc1 complex d) Cytochrome oxidase
d) Cytochrome oxidase
Which of the following conversions is not catalyzed by hexokinase? a) D-Glucose to glucose 6-phosphate b) D-Fructose to fructose 6-phosphate c) D-Mannose to mannose 6-phosphate d) D-Fructose to fructose 1-phosphate
d) D-Fructose to fructose 1-phosphate (Explanation: Conversion of D-Fructose to fructose 1-phosphate is catalyzed by fructokinase.)
8. Hydrolysis of sucrose yields ___________ a) D-galactose and D-glucose b) D-glucose and D-glucose c) D-galactose and D-fructose d) D-fructose and D-glucose
d) D-fructose and D-glucose (Explanation: Hydrolysis of sucrose yields D-fructose and D-glucose.)
Which compounds are responsible for the coordinated regulation of glucose and glycogen metabolism? a) NADH b) NAD+ c) Acetyl co-A d) Fructose 2, 6-bisphosphate
d) Fructose 2, 6-bisphosphate (Explanation: The hormonal regulation of glycolysis and gluconeogenesis is mediated by fructose 2, 6-bisphosphate.)
When blood sugar levels fall, glycolysis is halted in liver to allow ___________ a) Homeostasis b) Anaerobic respiration c) Aerobic respiration d) Gluconeogenesis
d) Gluconeogenesis (Explanation: Gluconeogenesis produces glucose in order to compensate the fall.)
Which of the following statements is true? a) High insulin/glucagon ratio activates lipolysis in muscle b) High insulin/glucagon ratio inhibits lipolysis in liver c) High insulin/glucagon ratio activates lipolysis in adipocytes d) Low insulin/glucagon ratio activates lipolysis in adipocytes
d) Low insulin/glucagon ratio activates lipolysis in adipocytes (Explanation: A high insulin/glucagon inactivates lipolysis.)
Which of the following is not a factor determining the activity of an enzyme? a) Association with regulatory protein b) Sequestration c) Allosteric regulation d) Nucleotides
d) Nucleotides (Explanation: Association with regulatory protein, sequestration, allosteric regulation and covalent modification are the factors determining the activity of an enzyme.)
Whenever the cell's ATP supply is depleted, which of the following enzyme's activity is increased? a) Hexokinase b) Pyruvate kinase c) Glucokinase d) Phosphofructokinase-1
d) Phosphofructokinase-1 (Explanation: Phosphofructokinase-1 is a regulatory enzyme; it is the major point of regulation in glycolysis. Its activity is increased whenever the cell's ATP supply is depleted.)
Which of the following enzymes is involved in fatty acid synthesis? a) Hexokinase II b) Hexokinase IV c) PFK-2/FBPase-2 d) Pyruvate dehydrogenase
d) Pyruvate dehydrogenase (Explanation: Hexokinase II and hexokinase IV involved in glycolysis.)
Three reactions of glycolysis are so exergonic, which are not catalyzed by? a) Hexokinase b) PFK-1 c) Pyruvate kinase d) Pyruvate dehydrogenase
d) Pyruvate dehydrogenase (Explanation: Three glycolytic enzymes are subjected to allosteric regulation: hexokinase IV, PFK-1 and pyruvate kinase.)
An endergonic reaction ____________ a) Proceeds spontaneously b) Does not require activation energy c) Releases energy d) Requires energy
d) Requires energy
Which of the following statements is false about ATP hydrolysis? a) It is highly exergonic b) Activation energy is relatively high c) ∆G'°=-30.5kJ/mol d) ∆G'°=30.5kJ/mol
d) ∆G'°=30.5kJ/mol (Explanation: ∆G'° should be negative for an exergonic process.)
