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Biochemistry MCQs- MAY 12

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Quiz on Biochemistry MCQs- MAY 12, created by MatthewEllis96 on 02/02/2015.
MatthewEllis96
Quiz by MatthewEllis96, updated more than 1 year ago
MatthewEllis96
Created by MatthewEllis96 almost 10 years ago
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Question 1

Question
The glycolytic pathway in dinosaurs
Answer
  • Was likely to be completely different to modern day animals, because every organism has different metabolic pathways
  • Was likely to be completely different to modern day organisms because they eat different types of food
  • Was likely to be similar or identical to modern day organisms, because metabolic pathways have been highly conserved through evolution
  • Is something we cannot make meaningful predictions about because we have no knowledge of how metabolism has evolved

Question 2

Question
In thin layer chromatography, ninhydrin can be used to stain which compounds?
Answer
  • Monosaccharides
  • Amino acids
  • Keto acids
  • All of the above

Question 3

Question
Which of the following lists contains the components of a phospholipid?
Answer
  • Choline, phosphate group, glycerol, fatty acids
  • Choline, phosphate group, glyceraldehyde, fatty acids
  • Carnitine, phosphate group, glycerol, amino acids
  • Carnitine, phosphate group, glyceraldehyde, amino acids

Question 4

Question
Testosterone belongs to which class of compounds?
Answer
  • Fats
  • Oils
  • Ketose monosaccharides
  • Sterols

Question 5

Question
Which of the following passes easily through phospholipid bilayers?
Answer
  • Chloride ions
  • ATP
  • Glucose 6-phosphate
  • Water

Question 6

Question
Peripheral membrane proteins
Answer
  • Pass through the cell membrane
  • Are non-covalently associated with integral membrane proteins
  • Are covalently linked to membrane lipids
  • Are always linked to sugars

Question 7

Question
Which of the following fatty acids is likely to have the highest melting temperature?
Answer
  • One with 14 carbon atoms and no double bonds
  • One with 14 carbon atoms and one double bond
  • One with 16 carbon atoms and no double bonds
  • One with 16 carbon atoms and one double bond

Question 8

Question
In the furanose ring form of β-D-fructose, how many of the carbon atoms are chiral?
Answer
  • 0
  • 2
  • 4
  • 6

Question 9

Question
Cellulose is a polymer of
Answer
  • α-D-glucose units only
  • β-D-glucose units only
  • α-D-glucose and β-D-fructose units
  • β-D-glucose and α-D-fructose units

Question 10

Question
In catabolic (degradative) reactions in humans, the most commonly used oxidising cofactors are
Answer
  • NAD+ and FAD
  • NADP+ and FAD
  • NADH and FADH2
  • NADPH and FADH2

Question 11

Question
Considering only the glycolytic pathway, what is the net gain in ATP molecules, per molecule of glucose processed?
Answer
  • 0
  • 1
  • 2
  • 4

Question 12

Question
Under anaerobic conditions, glycolysis in mammals can result in the compound lactose. Why?
Answer
  • To make ATP by substrate level phosphorylation
  • To regenerate NAD+
  • To make NADH for oxidative phosphorylation
  • To replenish Krebs’ (tricarboxylic acid) cycle intermediates

Question 13

Question
Which of the following statements about gluconeogenesis is TRUE?
Answer
  • Glucose is generated from the hydrolysis of phosphate from glucose 6-phosphate. No ATP is produced in this reaction.
  • Glucose is generated from the hydrolysis of phosphate from glucose 6-phosphate. One molecule of ATP is produced in this reaction.
  • In mammals, acetyl coenzyme A (AcCoA) can be a starting point.
  • The reactions are exactly the same as glycolysis, except in reverse.

Question 14

Question
Isomerisation of glucose 1-phosphate to glucose 6-phosphate occurs in
Answer
  • Glycolysis and gluconeogenesis
  • Glycogen synthesis and degradation
  • Glycolysis and the Leloir pathway
  • The Leloir pathway and glycogen degradation

Question 15

Question
In the Calvin cycle, carbon dioxide reacts with ribulose 1,5-bisphosphate. The first product(s) of this reaction is/are:
Answer
  • Two molecules of 3-phosphoglycerate
  • Two molecules of glyceraldehyde 3-phosphate
  • One molecule of glucose 6-phosphate
  • One molecule of fructose 6-phosphate

Question 16

Question
In Calvin’s experiments to identify the compounds in the Calvin cycle, the function of the hot ethanol was
Answer
  • To shield the algae from the heat of the lamps
  • To provide a source of carbon atoms for the algae
  • To kill the algae after a defined time point
  • To solublise the compounds in the algae

Question 17

Question
The main source of energy for sperm cells is
Answer
  • Glucose
  • Fatty acids
  • Glycerol
  • Fructose

Question 18

Question
The transition state in an enzyme-catalysed reaction:
Answer
  • Is always covalently associated to the enzyme.
  • Is never covalently associated to the enzyme.
  • Can never be observed experimentally.
  • Can often be similar in structure to potent enzyme inhibitors.

Question 19

Question
In enzyme catalysis, the term ‘approximation’ refers to:
Answer
  • A catalytic strategy that facilitates transition state stabilisation through formation of covalent bonds between a substrate and amino acid groups in the active site.
  • A catalytic strategy that facilitates transition state stabilisation through formation of hydrogen bonds and electrostatic interactions between a substrate and amino acid groups in the active site.
  • A catalytic strategy that facilitates transition state stabilisation through interaction with metal ions in the active site.
  • A catalytic strategy that facilitates transition state stabilisation through direct transfer of a proton to the substrate from an acidic amino acid group in the active site.

Question 20

Question
The Urea cycle:
Answer
  • Is completely located in the mitochondrial matrix – preventing the exposure of free ammonium to other components of the eukaryote cell.
  • Allows free ammonia obtained directly from de-amination of glutamate to be converted to urea – preventing the exposure of free ammonium to other components of the eukaryote cell.
  • Allows free ammonia obtained directly from de-amination of tryptophan to be converted to urea – preventing the exposure of free ammonium to other components of the eukaryote cell.
  • Is completely located in the cytoplasm of the cell – preventing the exposure of free ammonium to other components of the eukaryote cell.

Question 21

Question
Serine proteases:
Answer
  • Are proteases that hydrolyse polypeptides with serine in the F1 position
  • Are proteases that are found in the cytoplasm of all cells
  • Utilise a serine residue at the active site to facilitate substrate binding
  • Utilise a serine residue at the active site to facilitate cleavage of peptide bonds

Question 22

Question
Consider an enzyme that shows Michaelis-Menton kinetics where: vo = Vmax . [S] / (Km + [S]) If a substrate, S, is present at a concentration of 4 mM, and Km is 2 mM, the rate of reaction (vo) measured will be:
Answer
  • Half of Vmax
  • Two thirds of Vmax
  • Double Vmax
  • Three times Vmax

Question 23

Question
In acid-base catalysis:
Answer
  • An acidic- or basic- amino acid in the active site of an enzyme facilitates transition state formation by hydrogen abstraction from an appropriate substrate.
  • An acid- or basic- substrate in the active site of an enzyme facilitates transition state formation by hydrogen abstraction from a catalytic amino acid in the active site.
  • Both are correct.
  • Neither are correct.

Question 24

Question
The protein ubiquitin:
Answer
  • Can be covalently linked to proteins via the N-terminus glycine residue.
  • Is a polypeptide.
  • Is an essential component of eukaryote respiratory chains.
  • Can be covalently linked to proteins via isopeptide bond formation.

Question 25

Question
An oxyanion hole is:
Answer
  • A region of the enzyme active site that facilitates binding of positively charged substrates through their association with oxygen-containing amino-acid side chains in the enzyme.
  • A region of the enzyme active site that facilitates binding of negatively charged substrates through their association with oxygen-containing amino acid side chains in the enzyme.
  • A region of the active site that facilitates binding of positively charged oxygen containing groups present in a substrate.
  • A region of the active site that facilitates binding of negatively charged oxygen-containing groups present in a substrate.

Question 26

Question
If the ΔG°′ of the reaction Malate → Oxaloacetate is +30 kJ/mol, what will happen in the presence of malate dehydrogenase under standard conditions?
Answer
  • The reaction will proceed fast with the formation of the explosive products.
  • The reaction will not occur spontaneously.
  • The reaction will never reach equilibrium.
  • The reaction will proceed spontaneously from left to right.

Question 27

Question
Which of the following redox couple have the highest midpoint redox potential?
Answer
  • ubiquinol/ubiquinone
  • NADH/NAD+
  • H2O/½O2
  • ferrocytochrome c/ferricytochrome c

Question 28

Question
What is the source of energy for ATP synthesis in mitochondria?
Answer
  • AMP, ADP and inorganic phosphate
  • Gradient of Na+ across the inner mitochondrial membrane
  • Matrix fumarase and aconitase
  • None of the above

Question 29

Question
Which of the following cannot reduce mitochondrial respiratory chain in normal conditions?
Answer
  • NADH
  • Oxygen
  • FADH2
  • Ubiquinol

Question 30

Question
The oxygen molecules released into the air as a product of photosynthesis comes from:
Answer
  • Light quanta
  • Cytochome c oxidase
  • Carbon dioxide
  • Water

Question 31

Question
Production of lactic acid in anaerobic muscle cells is:
Answer
  • Caused by breakdown of glycogen
  • Caused by a buildup of AMP
  • Coupled to the recycling of NAD+ to NADH by lactate dehydrogenase when it oxidises pyruvate
  • Due to pyruvate being reduced by lactate dehydrogenase while it recycles NADH to NAD+

Question 32

Question
Phosphofructokinase-1 activity is:
Answer
  • Inhibited by fructose 2,6-bisphosphate
  • Inhibited by AMP
  • Inhibited by citrate
  • Stimulated by citrate

Question 33

Question
The Warburg effect:
Answer
  • Is the inhibition of glycolysis that occurs in anaerobic cells when exposed to oxygen
  • Is the continued use of anaerobic fermentation by cancer cells even in the presence of oxygen
  • Is caused by an over-active glycerol phosphate shuttle in cancer
  • Is due to the inhibition of phosphofructokinase-1 by AMP

Question 34

Question
Glycogen synthase activity is:
Answer
  • Inhibited by ATP
  • Stimulated by glucose 6-phosphate
  • Stimulated by fructose 1,6-bisphosphate
  • Inhibited by citrate

Question 35

Question
Phosphofructokinase-1 activity is:
Answer
  • Stimulated by citrate
  • Inhibited by AMP
  • Inhibited by citrate
  • Inhibited by fructose 2,6-bisphosphate

Question 36

Question
Which of the following is NOT true of Aldosterone?
Answer
  • It is a mineralocorticoid
  • It is a peptide hormone
  • It is a steroid hormone
  • It is released in response to angiotensin II

Question 37

Question
Calcitonin is a hormone that is released from:
Answer
  • The pituitary gland
  • The thyroid gland
  • The hypothalamus
  • The parathyroid gland

Question 38

Question
Which of the following is NOT a feature of metabolic pathways?
Answer
  • Sequential feedback inhibition
  • Common intermediate metabolites
  • The presence of aquaporins
  • End product inhibition

Question 39

Question
Which of the following is NOT true of the anabolic hormone insulin?
Answer
  • It increases glycogen synthesis
  • It increases fatty acid synthesis
  • It increases esterification of fatty acids
  • It increases protein breakdown (proteinolysis)

Question 40

Question
Which of the following has NOT been a commercial method for the synthesis of artificial human insulin?
Answer
  • Separate A- and B-chain synthesis in E. coli
  • Phage display in E. coli
  • Pro-insulin synthesis in E. coli
  • Biosynthesis in brewer’s yeast (Saccharomyces cerevisiae)
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