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Biochemistry MCQs- August 11

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Quiz on Biochemistry MCQs- August 11, created by MatthewEllis96 on 02/02/2015.
MatthewEllis96
Quiz by MatthewEllis96, updated more than 1 year ago
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Created by MatthewEllis96 over 9 years ago
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Question 1

Question
IF WE WERE ABLE TO DETERMINE THE REACTIONS OF THE KREBS’ (TRICARBOXYLIC ACID) CYCLE FROM A WOOLLY MAMMOTH, WOULD YOU EXPECT THEM TO BE:
Answer
  • Totally different from the ones found in humans, but similar to those in elephants
  • Essentially the same as the ones found in both humans and elephants
  • Totally different to the ones found in humans and elephants
  • Similar to those in other extinct mammals, but very different from anything alive today

Question 2

Question
AN END-PRODUCT CAN ACT TO INHIBIT AN ENZYME BY BINDING AT THE:
Answer
  • Transitional site
  • Active site
  • Activation site
  • Allosteric site

Question 3

Question
THE SINGLE BIGGEST SIDE-EFFECT OF INSULIN THERAPY IS:
Answer
  • A fear of needles
  • Hyperactivity
  • Hypoglycaemia
  • Hyperglycaemia

Question 4

Question
WHICH OF THE FOLLOWING IS A COMMON PHYSIOLOGICAL METHOD OF LOWERING BODY TEMPERATURE?
Answer
  • Stimulation of the mitochondria in brown fat cells
  • Rhythmic Stimulation of skeletal muscle
  • Increased thyroid gland activity
  • Accelerated respiration

Question 5

Question
WHICH OF THE FOLLOWING STATEMENTS CONCERNING ENZYME CASCADES IS FALSE?
Answer
  • They amplify and diversify signals of hormones such as cyclic AMP
  • They are usually found in the extracellular space
  • They often involve second messengers
  • Multiple enzymes undergo conformational change and become activated

Question 6

Question
WHICH OF THE FOLLOWING STATEMENTS CONCERNING STEROID HORMONES IS TRUE?
Answer
  • They bind to cytoplasmic and/or nuclear proteins to form a hormone receptor complex
  • They are transcription factors
  • They bind and activate membrane-bound receptors
  • They are hydrophilic compounds

Question 7

Question
THE ENZYME-SUBSTRATE COMPLEX:
Answer
  • Is a key concept that helps to explain how enzymes reduce activation energy for chemical reactions.
  • Is a key concept that helps to explain how enzymes can reduce the Gibb’s free energy for a chemical reaction.
  • Is a key concept that helps to explain how enzymes can exhibit diverse substrate specificity.
  • Is a key concept that helps to explain how enzymes may exhibit Michaelis-Menton kinetics.

Question 8

Question
CONSIDER AN ENZYME THAT SHOWS MICHAELIS-MENTON ENZYME KINETICS, WHERE: Vo = Vmax . [S] / Km + [S] If a substrate, S, is present at a concentration of 6 mM, and Km is 2 mM, the rate of reaction (Vo) measured will be:
Answer
  • One third of Vmax
  • Three times Vmax
  • Three quarters of Vmax
  • Six times Vmax

Question 9

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 10

Question
THE ENTHALPY CHANGE ASSOCIATED WITH A BIOCHEMICAL REACTION:
Answer
  • Is a term used to describe the amount of randomness or disorder that results as the reaction proceeds
  • Is a term used to describe the amount of ‘free energy’ change that results as the reaction proceeds
  • Is a term used to describe the amount of heat that is produced or consumed as the reaction proceeds
  • Is always determined at room temperature (25oC)

Question 11

Question
ENZYMES USUALLY UTILISE ONE OR MORE TRANSITION METAL ATOMS AT THE ACTIVE SITE TO:
Answer
  • Facilitate substrate binding
  • Facilitate transition state formation
  • Facilitate stabilisation of the tertiary structure
  • Facilitate conformational changes in the protein during the catalytic cycle

Question 12

Question
ENZYMES:
Answer
  • Reduce the entropy associated with chemical reactions
  • Reduce the enthalpy associated with chemical reactions
  • Reduce the Gibb’s free energy associated with chemical reactions
  • Reduce the activation energy associated with chemical reactions

Question 13

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 14

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 15

Question
THE UBIQUITIN PROTEIN:
Answer
  • Is only found in eukaryotic cells
  • Is only found in bacterial cells
  • Is a key component of the Urea cycle
  • Is a key component of the Ubiquitin cycle

Question 16

Question
THE ALANINE CYCLE:
Answer
  • Is completely located in the mitochondrial matrix.
  • Facilitates transport of ammonia produced in the liver to the muscles where it can be used in anabolic processes - preventing the exposure of free ammonium to other components of eukaryote tissues.
  • Facilitates transport of ammonia produced in the muscles to the liver where it can be effectively removed from the body - preventing the exposure of free ammonium to other components of eukaryote tissues.
  • Is completely located in the cytoplasm of the cell – preventing the exposure of free ammonium to other components of eukaryote tissues.

Question 17

Question
THE MOST COMMON FORM OF FRUCTOSE IN SOLUTION IS:
Answer
  • A pyranose (six-membered) ring form
  • A furanose (five-membered) ring form
  • A straight chain, ketone form
  • A straight chain, aldehyde form

Question 18

Question
FATTY ACIDS:
Answer
  • Have a hydrophobic aliphatic carbon chain and a hydrophilic carboxylic acid group
  • Have a hydrophilic aliphatic carbon chain and a hydrophobic carboxylic acid group
  • Have a hydrophobic aliphatic carbon chain and a hydrophobic carboxylic acid group
  • Have a hydrophilic aliphatic carbon chain and a hydrophilic carboxylic acid group

Question 19

Question
TESTOSTERONE IS:
Answer
  • A sterol
  • A ketose monosaccharide
  • A fatty acid
  • A cofactor

Question 20

Question
WHICH IF THESE MOLECULES IS COMMONLY INVOLVED IN CELL SIGNALLING AND RIBOSOMAL TRANSLOCATION?
Answer
  • TTP
  • CTP
  • UTP
  • GTP

Question 21

Question
THE PRECURSORS FOR THE BIOSYNTHESIS OF SUCROSE ARE:
Answer
  • UDP-glucose and fructose 6-phosphate
  • UDP-fructose and glucose 6-phosphate
  • UDP-glucose and fructose
  • UDP-fructose and glucose

Question 22

Question
TO DETERMINE THE IDENTITIES OF THE COMPOUNDS IN THE CALVIN CYCLE, MELVIN CALVIN USED:
Answer
  • Nuclear magnetic resonance spectroscopy and chemical analysis
  • Paper chromatography and mass spectrometry
  • Paper chromatography and chemical analysis
  • Chemical analysis and mass spectrometry

Question 23

Question
TRIOSE PHOSPHATE ISOMERASE CATALYSES THE ATTAINMENT OF EQUILIBRIUM BETWEEN THE GLYCOLYTIC INTERMEDIATES GLYCERALDEHYDE 3-PHOSPHATE AND DIHYDROXYACETONE PHOSPHATE. UNDER THE CONDITIONS PREVAILING IN A HUMAN CELL, ON WHICH SIDE DOES THE EQUILIBRIUM LIE?
Answer
  • It is not possible to know this from the information provided
  • Dihydroxyacetone phosphate
  • The equilibrium is approximately equally balanced
  • Glyceraldehyde 3-phosphate

Question 24

Question
CONSIDER TWO REACTIONS. REACTION 1 HAS A ΔG°′ VALUE OF -20 kJ.mol-1 AND REACTION 2 HAS A ΔG°′ VALUE OF -50 kJ.mol-1. WHICH REACTION PROCEEDS AT THE FASTEST RATE AT ROOM TEMPERATURE AND PRESSURE AND pH 7?
Answer
  • Reaction 1
  • Reaction 2
  • They both occur at much the same rate
  • It is not possible to know this from the data provided

Question 25

Question
IN GLYCOLYSIS, THE CONVERSION OF PHOSPHOENOLPYRUVATE TO PYRUVATE IS COUPLED TO:
Answer
  • The phosphorylation of ADP to make ATP
  • The phosphorylation of GDP to make GTP
  • The reduction of NAD+ to make NADH
  • The oxidation of NADPH to make NADP+

Question 26

Question
IN YEAST UNDER ANAEROBIC CONDITIONS, ETHANOL IS PRODUCED AT THE END OF THE GLYCOLYTIC PATHWAY. WHY IS THIS ADVANTAGEOUS TO THE YEAST?
Answer
  • It enables the regeneration of NAD+
  • It enables it to produce more NADH
  • A molecule of ATP can be produced from the reaction
  • It helps the brewing industry

Question 27

Question
UNDER ANAEROBIC CONDITIONS IN HUMANS, HOW MANY MOLECULES OF CARBON DIOXIDE (CO2) ARE PRODUCED BY THE METABOLISM OF ONE MOLECULE OF GLUCOSE BY GLYCOLYSIS AND SUBSEQUENT PATHWAYS?
Answer
  • 6
  • 4
  • 2
  • 0

Question 28

Question
LACTOSE IS A DISACCHARIDE OF:
Answer
  • Glucose and mannose
  • Mannose and fructose
  • Galactose and fructose
  • Glucose and galactose

Question 29

Question
THE COFACTOR FAD (FLAVIN ADENINE DINUCLEOTIDE) IS COMPOSED OF WHICH SUBUNITS?
Answer
  • Flavin, ribose, adenine and three phosphates
  • Flavin, two riboses, two adenines and a phosphate
  • Flavin, two riboses, two adenines and two phosphates
  • Flavin, ribose, adenine and two phosphates

Question 30

Question
NADPH IS USED IN THE CALVIN CYCLE TO:
Answer
  • Oxidise 1,3-bisphosphoglycerate
  • Reduce 1,3-bisphosphoglycerate
  • Oxidise ribulose 1,5-bisphosphate
  • Reduce ribulose 1,5-bisphosphate

Question 31

Question
IN GLUCONEOGENESIS, THE CORRECT SEQUENCE OF COMPOUNDS IN THE CONVERSION OF PYRUVATE TO PHOSPHOENOLPYRUVATE IS:
Answer
  • Pyruvate → Oxaloacetate → Phosphoenolpyruvate
  • Pyruvate → Lactate → Phosphoenolpyruvate
  • Pyruvate → Succinate → Phosphoenolpyruvate
  • Pyruvate → 1,3-bisphosphoglycerate → Phosphoenolpyruvate

Question 32

Question
THE INCREASE IN ATP LEVELS THAT ACCOMPANIES THE "PASTEUR EFFECT" CAUSES:
Answer
  • decreased glycolytic flux by allosteric stimulation of lactate dehydrogenase
  • allosteric inhibition of fructose 1,6-bisphosphatase
  • allosteric inhibition of phosphofructokinase-1
  • increased glycolytic flux by allosteric activation of phosphofructokinase-2

Question 33

Question
GLYCOGEN PHOSPHORYLASE IS:
Answer
  • inhibited by phosphorylation
  • activated by phosphorylation
  • activated by glucose
  • inhibited by AMP

Question 34

Question
PROTEIN KINASE A:
Answer
  • is an allosteric enzyme
  • phosphorylates phosphorylase kinase
  • phosphorylates glycogen phosphorylase
  • is activated by ADP

Question 35

Question
ADRENALINE:
Answer
  • induces glycogen synthesis in the liver
  • induces gluconeogenesis in the liver
  • accelerates glyconeogenesis in the heart
  • inhibits glycolysis in the heart

Question 36

Question
GLYCOGEN PHOSPHORYLASE KINASE
Answer
  • is activated by cAMP
  • is activated by dephosphorylation
  • is activated by autophosphorylation
  • is activated by protein kinase A

Question 37

Question
WHAT IS THE SOURCE OF ENERGY FOR ATP SYNTHESIS IN MITOCHONDRIA?
Answer
  • ADP and inorganic phosphate
  • Gradient of NADH across the inner mitochondrial membrane
  • Matrix aconitase
  • None of the above

Question 38

Question
WHAT IS THE OVERALL EQUATION FOR PHOTOSYNTHESIS?
Answer
  • 18 CO2+ 2 NADPH + 3 ATP + light → 2 NADPH + 3 Glucose-1-phosphate + 3 ADP + 18 O2
  • 2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light → 2 NADPH + 2 H+ + 3 ATP + O2
  • 2 H2O + 2 NAD+ 2 Pi → 2 NADPH + 2 H+ + O2 + light
  • CO2 + light + H2O → Glucose + O2

Question 39

Question
WHICH OF THE FOLLOWING IS NOT A REDOX CENTRE FOR RESPIRATORY CHAIN?
Answer
  • NADH
  • Cytochrome c
  • Oxygen
  • FADH2

Question 40

Question
THE OXYGEN MOLECULES RELEASED INTO THE AIR AS A PRODUCT OF PHOTOSYNTHESIS COMES FROM:
Answer
  • Light quanta
  • Cytochome c oxidase
  • Water
  • Carbon dioxide
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