Biochemistry MCQs Flashcards
1
Q
- Adenosine diphosphate is formed by…
a. A reaction between a phosphorylated compound and adenosine diphosphate
b. In aerobic metabolism and not anaerobic metabolism
c. By adenosine and 2 phosphate molecules
d. A reaction between a phosphorylated compound and adenosine monophosphate
A
d
2
Q
- A peptidase is an example of what type of enzyme?
a. Lyase
b. Transferase
c. Oxidoreductase
d. Hydrolase
A
d
3
Q
- In the induced fit model of enzymatic activity….
a. The binding of the enzyme to the substrate does not affect the structure of the substrate
b. The conformation of the active site is rigid
c. Binding of the substrate to a flexible enzyme active site results in changes in the structure of the substrate
d. The complimentary shapes of the active site of the enzyme and the substrate are responsible for the catalytic activity of the enzyme
A
c
4
Q
- pH has a profound effect on the catalytic effect of enzymes because…
a. It causes competitive inhibitors to bind to the active site
b. It makes co-factors available to the enzyme thus converting it to its active form
c. pH causes the substrate to degrade
d. pH affects the conformation at the active site and thus the ability of the enzyme to bind the substrate
A
d
5
Q
- Which of the following statements about enzyme catalysed reactions is true?
a. Enzymes do not form complexes with their substrates
b. Enzymes alter the activation energy of a reaction
c. Enzyme catalysis is not influenced by pH
d. Enzymes are not involved in the digestion of food
A
b
6
Q
- In which section of the human digestive tract does the digestion of polypeptides take place?
a. Small intestine
b. Stomach
c. Mouth
d. Duodenum
A
d
7
Q
- The enzyme trypsin acts on which substrate and can be classified as what type of enzyme?
a. Proteins, hydrolase
b. Dextrans, reductase
c. Peptides, hydrolase
d. Amino acids, ligase
A
c
8
Q
- What have carbohydrates been catabolised into by the time they enter the small intestine?
a. Polysaccharides
b. Starches
c. Monosaccharides
d. Disaccharides
A
d
9
Q
- The loss and gain of electrons is what type of chemical reaction?
a. Reduction
b. Oxidation
c. Redox
d. Condensation
A
c
10
Q
- Which of the following reactions in glycolysis, does not yield ATP?
a. Glyceraldehyde-3-phosphate 1,3 biphosphoglycerate
b. Phosphoelnolpyruvate (PEP) pyruvate
c. 1,3 biphosphoglycerate 3-phosphoglycerate
d. B and C
A
a
11
Q
- Which reaction in the gluconeogenesis pathway occurs in the mitochondria and not in the cytosol?
a. Fructose-1,6-biphosphate fructose-6-phosphate
b. Pyruvate oxaloacetate
c. Glucose-6-phosphate glucose
d. Oxaloacetate PEP
A
b
12
Q
- Approximately how many proteins are required to facilitate the reaction below?
6CO2 + 12H2O + Light C6H12O6 + 6O2 + 6H2O
a. 1
b. 20
c. 30
d. 15
A
c
13
Q
- What process provides the electrons to replace those lost in Photosystem II in photosynthesis?
a. The electron transport chain
b. Cellular respiration
c. Proton flow
d. The splitting of water
A
d
14
Q
- What is the overall energy yield from the oxidation of 1 molecule of behenic acid (C22:0)?
a. 126
b. 136
c. 150
d. 164
A
c
15
Q
- In gluconeogenesis how many ATP molecules (or equivalents) are used in the conversion of pyruvate to glucose?
a. 4
b. 2
c. None
d. 6
A
b
16
Q
- Where in the cell does chemiosmosis take place?
a. The cytosol
b. The chloroplast and the mitochondria
c. The nucleus and the cytosol
d. The mitochondria only
A
b
17
Q
- Which enzymes breaks proteins into peptides?
a. Pepsin
b. Isomerases
c. Lyases
d. Maltase
A
a
18
Q
- Which part of the ruminant digestive system is very similar to the stomach of non-ruminants?
a. Abomasum
b. Omasum
c. Reticulum
d. Rumen
A
a
19
Q
- Which of the following is NOT a characteristic of allosterically regulated enzymes?
a. They bind to the active site of the enzyme
b. They are not influenced by the concentration of the enzyme
c. Allosteric regulation can involve either stimulation and inhibition of enzyme activity
d. Their effect is not reversed by adding substrate
A
a
20
Q
- What type of enzyme could be described as an enzyme which catalyses the conversion of a molecule into an isomer?
a. Isomerase
b. Hydrolase
c. Lyase
d. Oxidoreductase
A
a
21
Q
- In the lining of the stomach wall what type of cell is responsible for the production of hydrochloric acid?
a. Mucous cells
b. Gastric cells
c. Parietal cells
d. Chief cells
A
c
22
Q
- How many rounds of β-oxidation are necessary to completely oxidise lignoceric acid (C24:0) to acetyl CoA?
a. 12
b. 8
c. 11
d. 24
A
c
23
Q
- What metabolic process does the equation below summarise?
(Glucose)n + glucose + 2ATP + H2O (Glucose)n+1 + 2ADP + 2Pi + 2H+
a. Glycogenesis
b. Glycolysis
c. Gluconeogenesis
A
a
24
Q
- Which receptor is responsible for the uptake of chylomicron remnants by the liver?
a. apoCII
b. apoB-100
c. apoB-48
d. apo-E
A
d
25
Q
- The equation below can be used to represent which biosynthetic process?
2H2O + 8 photons + 2NADP + ~3ADP + ~3Pi O2 + ~3ATP + 2NADPH
a. Substrate level phosphorylation
b. Photophosphorylation
c. The Calvin Cycle
A
b
26
Q
- Per molecule of glucose how many ATP (or equivalents) are formed by substrate level phosphorylation in the pay-off phase of glycolysis?
a. None
b. 4
c. 6
d. 2
A
d
27
Q
- Which of the enzymes below has a role in glycolysis and gluconeogenesis?
a. Glucose-6-phosphatase
b. Phosphofructokinase
c. Fructose-1,6-phosphatase
d. Phosphoglycerate kinase
A
c
28
Q
- The conversion of glucose-6-phosphate to glucose-1-phosphate occurs in which metabolic process and is catalysed by which enzyme?
a. Glucose-6-Phosphatase, glycogenolysis
b. Phosphoglucomutase, glycogenolysis
c. Phosphoglucomutase, glycogenesis
d. Glycogen Phosphorylase, glycogenolysis
A
c
29
Q
- Which of the following is not one function of adenosine triphosphate in the cell?
a. As a storehouse for energy
b. Transport work
c. Mechanical work
A
a
30
Q
- A ketogenic amino acid is a molecule…
a. Whose carbon skeleton can be degraded to pyruvate
b. That can be degraded to glucose
c. That upon a series of catabolic reactions will yield acetyl-CoA
d. Cannot be used as a source of energy
A
c
31
Q
- If [NADH] mitochondria is lower than the [NADH] cytosol then electrons from glycolysis are passed to _______ shuttle resulting in the formation of _______ ATP?
a. Malate aspartate, 2.5 ATP
b. Glycerol phosphate, 1.5 ATP
c. Glycerol phosphate, 2.5 ATP
d. Malate aspartate, 1.5 ATP
A
a
32
Q
- What will the absence of Malonyl CoA in a hepatocyte have on the extent of ketogenesis?
a. Stimulates the activity of CPT I, dampens down the extent of ketogenesis
b. Inhibits the activity of CPT I, dampens down the extent of ketogenesis
c. Inhibits the activity of CPT I, increases the extent of ketogenesis
d. Stimulates the activity of CPT I, increases the extent of ketogenesis
A
d
33
Q
- Which of these equations can be used to represent the formation of palmitate?
a. 8Acetyl-CoA + 7ATP + 14NADPH + 14H+ palmitate + 8CoA + 7ADP + 7Pi + 14NADP+ + 6H2O
b. 7Acetyl-CoA + 7CO2 + 7ATP 7malonyl-CoA + 7ADP + 7Pi
c. Acetyl-CoA + 7ATP + 14NADPH + 14H+ palmitate + 8CoA + 7ADP + 7Pi + 14NADP+
A
a
34
Q
- Which lipoprotein transports dietary cholesterol and triglycerides to other parts of the body?
a. VLDL
b. HDL
c. IDL
A
a
35
Q
- What is the overall energy yield (in molecules of ATP) from the oxidation of 1 molecule of Cerotic acid (C26:0) to acetyl-CoA (including beta-oxidation derived reduced coenzymes)?
a. 450ATP
b. 150ATP
c. 178ATP
A
c
36
Q
- ATP at a high concentration acts as what type of inhibitor on phosphofructokinase?
a. Substrate level phosphorylation
b. Allosteric activator
c. None of the above
d. Allosteric inhibitor
A
c
37
Q
- What effect will insulin have on glycogen accumulation in the liver and muscles?
a. It converts glycogen synthase from an inactive to an active form
b. It promotes the activity of glycogen synthase
c. It will inhibit glycogen accumulation
d. It will promote glycogen accumulation
A
d
38
Q
- Which of the following statements about reaction rate is true?
a. Reaction rates are independent from thermodynamic conditions (temperature)
b. The presence of enzymes does not affect the rate of a reaction
c. None of the above
d. The reaction rate is the speed at which the reaction proceeds towards the state of equilibrium between substrate and product
A
d
39
Q
- Which of the following statements describes the action of an enzyme during enzymatic catalysis?
a. The presence of an enzyme (E) alters the equilibrium from the substrate (S) to the product (P)
b. The presence of an enzyme (E) decreases the transition state free energy in the reaction from substrate (S) to product (P)
c. The presence of an enzyme (E) increases the transition free state energy in the reaction from substrate (S) to product (P)
d. The presence of an enzyme (E) decreases the free energy difference between substrate (S) and product (P)
A
b
40
Q
- In what section of the human digestive tract does the main digestion of lipids take place?
a. Stomach via pepsin
b. Small intestine via pancreatic lipases
c. Large intestine via peptidases
d. Mouth via salivary amylase
A
b
41
Q
- During digestion, food passes through a number of organs that make up the digestive tract. What is the order in which food transits through the various organs?
a. Mouth, stomach, oesophagus, small intestine, large intestine and rectum
b. Mouth, oesophagus, stomach, large intestine, small intestine and rectum
c. Mouth, stomach, oesophagus, large intestine, small intestine and rectum
d. Mouth, oesophagus, stomach, small intestine, large intestine and rectum
A
d
42
Q
- What is the function of bile secreted by the pancreas with regard to the digestion of lipids?
a. It has no role in the digestion of lipids
b. It emulsifies fat droplets thus stopping them from aggregating
c. It neutralises acidic chyme entering the duodenum
d. It contains a number of carbohydrates
A
b
43
Q
- What have polysaccharides been catabolised into by the time they enter the small intestine?
a. Polysaccharides
b. Amino acids
c. Monosaccharides
d. Disaccharides
A
d
44
Q
- Which molecule reacts with oxaloacetate to form citrate and keep the TCA cycle moving?
a. Malate
b. Iso-citrate
c. Acetyl-Co-A
d. Pyruvate
A
c
45
Q
- The conversion of succinate to fumarate results in the reduction of what electron acceptor?
a. NAD+
b. NADH
c. FAD
d. FADH2
A
c
46
Q
- The enzyme acetaldehyde dehydrogenase is an example of?
a. A hydrolase
b. A transferase
c. A lyase
d. An oxidoreductase
A
d
47
Q
- The digestion of protein in the small intestine is catalysed predominantly by which enzyme?
a. Trypsin
b. Ptyalin
c. Pepsin
d. Pepsinogen
A
a
48
Q
- The conversion of one molecule of glucose to two molecules of pyruvate results in the net formation of?
a. 38 molecules of ATP
b. 2 molecules of ATP
c. 6 molecules of water
d. 3 molecules of ATP
A
d
49
Q
- The reduction of pyruvate to lactate
a. Reconverts NADH to NAD+
b. Provides more fuel to skeletal muscle than the conversion of glucose to pyruvate
c. Occurs under aerobic conditions
d. Produces 2 ATP
A
a
50
Q
- How many ATP molecules (or equivalents) does the conversion of pyruvate to form glucose consume?
a. 2
b. 4
c. 6
d. 8
A
c
51
Q
- In the mitochondrial matrix are
a. Glycogen molecules
b. All the components of the electron transport chain
c. The enzymes of the tricarboxylic acid cycle (Kreb’s cycle)
d. The enzymes of gluconeogenesis
A
c
52
Q
- To control the flux through a pathway, the most effective regulation points are
a. Reversible reactions
b. Irreversible reactions
c. Substrate-limited reactions
d. Fastest reactions
A
b
53
Q
- In the electron transport chain, which donor results in the generation of the most ATP?
a. FADH2
b. NADH
c. ATP
d. Carbon Dioxide
A
b
54
Q
- What cellular compartment becomes depleted of hydrogen ions during the mitochondrial electron transport?
a. Mitochondrial matrix
b. Ribosomes
c. Mitochondrial inter-membrane space
d. Cytosol
A
c
55
Q
- The passage of electrons from which enzyme complex in the electron transport chain is not accompanied by the pumping of protons into the intermembrane space?
a. NADH dehydrogenase
b. Succinate Co-Q reductase
c. Cytochrome C oxidase
d. Coenzyme Q-cytochrome C reductase
A
b
56
Q
- The formation of a molecule of ATP by ATP synthase from ADP and Pi by ATP synthase is an example of
a. Conversion of mechanical energy into chemical energy
b. Conversion of chemical energy into mechanical energy
c. Conversion of potential energy into chemical energy
d. None of the above
A
b
57
Q
- If the concentration of NADH is greater in the mitochondrial matrix than in the cytosol, how many ATP will arise from the oxidation of glyceraldehyde-3-phosphate in glycolysis per glucose molecule?
a. 5 ATP
b. 7 ATP
c. 3 ATP
d. 2 ATP
A
d
58
Q
- What two energy carrying molecules are produced by the light reactions of photosynthesis?
a. NADPH and ATP
b. NADPH and ADP
c. NADP+ and ATP
d. NADH and ATP
A
a
59
Q
- The light-independent reactions of photosynthesis take place in the
a. Chloroplasts
b. Thylakoid membranes
c. Grannum
d. Stroma
A
d
60
Q
- The Calvin cycle involves all of the following except
a. The fixing of carbon
b. Regeneration of NADP+
c. Reduction of Carbon
d. The production of carbon dioxide in the form of waste
A
d
61
Q
- A compound which exerts allosteric control over an enzyme
a. Is always the product of the reaction it affects
b. Binds to a site remote from the active site
c. Always inhibits the catalytic effect of the enzyme
d. Binds to the active site of the enzyme thus inhibiting binding of the substrate
A
b
62
Q
- In glycolysis high levels of glucose-6-phosphate in a cell will inhibit which enzyme?
a. Phosphofructokinase
b. Fructose 1,6-biphosphtase
c. Phosphorylase
d. Hexokinase
A
d
63
Q
- In glycolysis what effect would high levels of acetyl-coA have on the catalytic activity of pyruvate kinase?
a. No effect
b. It would inhibit the activity of the enzyme
c. It would promote the activity of the enzyme
d. Pyruvate kinase is not involved in glycolysis
A
b
64
Q
- How does glucagon and epinephrine increase the production of glucose via gluconeogenesis?
a. They have no effect on gluconeogenesis
b. They inhibit the activity of fructose 2,6-biphosphatase
c. They liberate glucose from glycogen stores
d. They inhibit the activity of phosphofructokinase-2
A
d
65
Q
- In a fight or flight situation what effect does epinephrine have on the catalytic activity of glycogen phosphorylase?
a. It is an allosteric promoter of the enzyme
b. It stimulates the conversion of the enzyme into its active form thus increasing the formation of glycogen
c. It inhibits the enzyme
d. It stimulates the conversion of the enzyme into its active form thus increasing release of glucose from glycogen
A
d
66
Q
- What is the overall energy yield of beta-oxidation of palmitate?
a. 108 ATP
b. 96 ATP
c. 80 ATP
d. 28 ATP
A
a
67
Q
- The equation below represents the overall energy balance for the metabolism of which fatty acid?
Palmitoyl-CoA + 7CoA + 7O2 + 28Pi + 28 ADP 8→Acetyl-CoA + 28 ATP + 7H2O
a. Linoleic acid (C18:2)
b. Palmitic acid (C16:0)
c. Arachadonic acid (C20:4)
d. Palmitoleic acid (C16:1)
A
b
68
Q
- What is the overall energy yield from the metabolism of stearic acid (C18:0)
a. 28 ATP
b. 42 ATP
c. 108 ATP
d. 122 ATP
A
d
69
Q
- Why are two additional enzymes required for the beta-oxidation of unsaturated fatty acids?
a. The presence and configuration of the double bonds mean the fatty acid is no longer a substrate for the enzymes required for oxidation of a saturated fatty acid
b. They contain trans double bonds
c. They contain double bonds between the alpha and beta carbons
d. No additional enzymes are require
A
a
70
Q
- What is the mechanism by which fatty acids enter mitochondrial matrix for beta-oxidation
a. Carnithine shuttle
b. Membrane diffusion
c. Electron transport chain
d. Transacyclase
A
a
71
Q
- When are ketone bodies formed in the liver?
a. When glucose levels are low
b. When there is excess of fatty acids in the blood
c. When liver glycogen reserves are full
d. When glucose is in plentiful supply
A
a
72
Q
- Brain cells can obtain energy from the oxidation of ketone bodies during starvation?
a. True
b. False
A
a
73
Q
- What effect will a high level of malonyl coA in the hepatocyte have on ketone body production?
a. It will dampen down ketone body production
b. It will increase ketone body production because there is more substrate available
c. It will inhibit the action of carnithine palmitoyl coA
d. No effect
A
a
74
Q
- Why would a low level of insulin production increase the production of ketone bodies
a. Changes the insulin/glucagon ratio
b. Insulin blocks lipolysis and therefore the substrate for ketone body production
c. Insulin increases the production of malonyl CoA which in turn inhibits CPT1 thus dampening down ketogenesis
d. Insulin blocks lipolysis and therefore the substrate for ketone body production
A
b
75
Q
- Where in the body are dietary fats emulsified into micelles?
a. Stomach
b. Duodenum
c. Ileum
d. Pancreas
A
b
76
Q
- Which lipoprotein has the function of removing cholesterol from plasma?
a. HDL
b. VLDL
c. LDL
d. Chylomicrons
A
a
77
Q
- Which of the following lipoproteins is the largest in size?
a. IDLs
b. Chylomicrons
c. VLDLs
d. LDLs
A
b
78
Q
- Which lipoprotein has the effect of transporting mainly endogenously produced triacylglycerols to the tissues from the liver?
a. IDLs
b. Chylomicrons
c. VLDLs
d. HDLs
A
c
79
Q
- Insulin has the effect of reducing plasma lipid concentration following a meal. Which of the following does it not do?
a. Stimulates the release of CCK
b. Stimulates lipoprotein lipase in adipose tissue
c. Suppresses release of VLDL from liver
d. Suppresses the intracellular lipolysis of stored TAG in adipose
A
a
80
Q
- How many common end products of AA catabolism can be identified?
a. 2
b. 4
c. 8
d. 6
A
d
81
Q
- What is the main pathway for pyruvate produced during amino acid catabolism
a. Glucogenesis
b. TCA cycle
c. Glycolysis
d. Oxidation of acetyl CoA
A
b
82
Q
- Why can’t ketogenic AA’s enter gluconeogenesis
a. They are converted to acetyl CoA during catabolism
b. There are no enzymes to do this
c. Their carbon skeletons are too long
d. They cannot be converted to acetyl CoA
A
a
83
Q
- Which two amino acids are purely ketogenic?
a. Phenylalanine and tyrosine
b. Leucine and lysine
c. Tryptophan and leucine
d. Isoleucine and methionine
A
b
84
Q
- How many amino acids are glucogenic and ketogenic?
a. 3
b. None
c. 5
d. 6
A
c