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Biochemistry MCQs- MAY 11

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

Question 1

Question
SUCROSE IS SYNTHESISED BY WHICH OF THESE GROUPS OF ORGANISMS?
Answer
  • Mammals
  • Birds
  • Bees
  • Trees

Question 2

Question
WHICH OF THE FOLLOWING LISTS CONTAINS ONLY ALDOSE, HEXOSE MONOSACCHARIDES?
Answer
  • Glucose, Fructose, Mannose
  • Sucrose, Fructose, Ribose
  • Mannose, Galactose, Glucose
  • Sucrose, Mannose, Glucose

Question 3

Question
WHICH IF THESE MOLECULES OR IONS WILL PASS MOST EASILY THROUGH A PHOSPHOLIPID BILAYER?
Answer
  • A sodium ion
  • Urea
  • A chloride ion
  • ATP

Question 4

Question
WHICH OF THE FOLLOWING CARBOHYDRATES IS COMMONLY USED AS THE ACTIVE INGREDIENT IN “FAKE TAN”?
Answer
  • Glyceraldehyde
  • Galactose
  • Ribose
  • Dihydroxyacetone

Question 5

Question
GLYCOGEN IS SYNTHESISED FROM WHICH PRECURSOR?
Answer
  • Glucose
  • UDP-glucose
  • Sucrose
  • Glucose 6-phosphate

Question 6

Question
IN THE FIRST REACTION OF THE LELOIR PATHWAY, GALACTOSE REACTS WITH ATP TO MAKE:
Answer
  • Galactose 1-phosphate
  • Galactose 2-phosphate
  • Galactose 4-phosphate
  • Galactose 6-phosphate

Question 7

Question
CONSIDER GLYCOLYSIS STARTING FROM GLUCOSE AND ENDING WITH PYRUVATE. WHAT IS THE NET GAIN OF ATP PER MOLECULE OF GLUCOSE?
Answer
  • No molecules
  • Two molecules
  • Four molecules
  • Six molecules

Question 8

Question
IN HUMANS, UNDER ANAEROBIC CONDITIONS, NADH PRODUCED IN GLYCOLYSIS IS REGENERATED BY THE REDUCTION OF WHICH COMPOUND TO LACTATE?
Answer
  • Acetyl Coenzyme A (AcCoA)
  • Pyruvate
  • Phosphoenolpyruvate
  • Ethanol

Question 9

Question
TO REPLENISH THE KREBS‟ (TRICARBOXYLIC ACID) CYCLE INTERMEDIATES, PHOSPHOENOLPYRUVATE (A THREE CARBON COMPOUND) IS CONVERTED TO OXALOACETATE (A FOUR CARBON MOLECULE). WHAT IS THE SOURCE OF THE ADDITIONAL CARBON ATOM?
Answer
  • ATP
  • Acetyl CoA
  • Pyruvate
  • Carbon dioxide (CO2)

Question 10

Question
AMYLOPECTIN, A COMPONENT OF STARCH CONTAINS GLUCOSE UNITS BONDED TOGETHER BY(1→4) GLYCOSIDIC LINKS AND WHAT OTHER LINKAGE?
Answer
  • α(1→2) glycosidic links
  • α(1→6) glycosidic links
  • β(1→2) glycosidic links
  • β(1→6) glycosidic links

Question 11

Question
MALONATE IS TOXIC BECAUSE:
Answer
  • It competitively inhibits succinate dehydrogenase
  • It blocks the oxygen binding site in cytochrome c oxidase
  • It reacts with ATP
  • It prevents cell membranes from forming

Question 12

Question
IN CALVIN‟S “LOLLIPOP” EXPERIMENT TO INVESTIGATE THE INTERMEDIATES IN THE CALVIN CYCLE, THE FUNCTION OF THE BOILING ETHANOL WAS:
Answer
  • To provide a source of energy for the cells
  • To shield the cells from heat from the lights
  • To kill the cells so that the reaction was stopped
  • To separate the products on paper chromatography

Question 13

Question
THE CALVIN CYCLE USES WHICH REDOX COFACTOR?
Answer
  • NADP+
  • NADPH
  • NAD+
  • NADH

Question 14

Question
FATTY ACIDS ARE CARRIED IN THE BLOOD LARGELY:
Answer
  • In aqueous solution, not in complex with any other molecules
  • In complex with carbohydrates
  • In complex with cholesterol
  • In complex with proteins

Question 15

Question
CHOLESTEROL:
Answer
  • Has no effect on the fluidity of cell membranes
  • Can only increase the fluidity of cell membranes
  • Can only decrease the fluidity of cell membranes
  • Can increase or decrease the fluidity of cell membranes

Question 16

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 17

Question
KOSHLAND‟S INDUCED FIT MODEL FOR ENZYME-SUBSTRATE COMPLEX FORMATION:
Answer
  • May explain why enzymes have particular substrate specificity.
  • May explain why enzymes are able to catalyse chemical reactions that cannot be facilitated in any other way
  • May explain why enzymes increase the rate of a reaction by reduction of the activation energy change for the reaction
  • May explain why enzymes can effectively reduce the loss of energy from a chemical reaction as heat

Question 18

Question
CONSIDER AN ENZYME THAT SHOWS MICHAELIS-MENTEN ENZYME KINETICS, WHERE: Vo = Vmax . [S] / Km + [S] If a substrate, S, is present at a concentration of 2 mM, and Km is 1 mM, the rate of reaction (Vo) measured will be:
Answer
  • Half of Vmax
  • Two thirds of Vmax
  • Double Vmax
  • Three times Vmax

Question 19

Question
THE ENZYME-SUBSTRATE COMPLEX:
Answer
  • Is easily observed through Michaelis-Menten kinetic experiments
  • Is sometimes present in Michaelis-Menten kinetic experiments
  • Is a concept used to explain the results of Michaelis-Menten kinetic experiments
  • Is completely irrelevant to Michaelis-Menten kinetic experiments

Question 20

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 sit 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 21

Question
THE CATALYTIC EFFICIENCY OF AN ENZYME CATALYSED REACTION:
Answer
  • Can be described by the ratio: kCAT/KM
  • Can be described by the ratio: KM/kCAT
  • Can be described by the ratio: Vmax/kCAT
  • Can be described by the ratio: kCAT/Vmax

Question 22

Question
THE TERM „APPROXIMATION‟ HAS A SPECIFIC MEANING IN ENZYME CATALYSIS. THIS IS BEST DESCRIBED AS:
Answer
  • A catalytic mechanism that facilitates transition state formation by covalent interactions.
  • A catalytic mechanism that facilitates substrate-enzyme complex formation by covalent interactions.
  • A catalytic mechanism that facilitates transition state formation by non-covalent interactions.
  • A catalytic mechanism that facilitates substrate-enzyme complex formation by non-covalent interactions.

Question 23

Question
PROTEOSOME-MEDIATED PROTEOLYSIS:
Answer
  • Is controlled by serine protease enzymes.
  • Is a key part of the control mechanism in the eukarote cell cycle
  • Is a key part of the control mechanism in the prokarote cell cycle
  • Is controlled by ubiquinone activating enzymes.

Question 24

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 deamination 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 deamination 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 25

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 26

Question
IF THE /_\G'° OF THE REACTION C D IS –20 kJ/mol, WHAT WILL HAPPEN IN THE PRESENCE OF A SPECIFIC ENZYME C-CONVERTASE UNDER STANDARD CONDITIONS?
Answer
  • The reaction will stop
  • The reaction will proceed spontaneously from left to right.
  • The reaction will never reach equilibrium.
  • The reaction will not occur spontaneously.

Question 27

Question
WHICH OF THE FOLLOWING IS AN EXERGONIC PROCESS?
Answer
  • Biosynthesis of NADPH
  • Transport of protons by respiratory chain
  • Oxygen reduction by cytochromec oxidase
  • Brain activity due to the thinking about this question

Question 28

Question
WHICH OF THE FOLLOWING STATEMENTS ABOUT MIDPOINT REDOX POTENTIALS IS INCORRECT?
Answer
  • Redox potentials can be used to calculate free energy changes
  • The strongest oxidants have the most negative potential.
  • Redox potential is measured in millivolts.
  • Oxygen reduction has a very high potential.

Question 29

Question
WHICH OF THE FOLLOWING REDOX COUPLE HAVE THE HIGHEST MIDPOINT REDOX POTENTIAL?
Answer
  • ubiquinol/ubiquinone
  • NADPH/NADP+
  • ferrocytochrome c/ferricytochrome c
  • H2O/½O2

Question 30

Question
WHICH OF THE FOLLOWING STATEMENTS ABOUT MITOCHONDRIAL ELECTRON TRANSPORT IS INCORRECT?
Answer
  • The inner mitochondrial membrane is positively charged on the inside.
  • The enzyme ATP-synthase can synthesise ATP.
  • Electron transfer to O2 is highly exergonic.
  • The proton motive force can be used for active transport.

Question 31

Question
WITH RESPECT TO BIOCHEMICAL PATHWAYS „BRANCHING POINTS‟ ARE:
Answer
  • Catalysts of the individual steps in a metabolic pathway.
  • Compounds which are intermediates between reactants and end products
  • Point at which an intermediate may proceed down one of several alternative pathways
  • Substrates involved in the metabolic pathway

Question 32

Question
WHICH ONE OF THE FOLLOWING IS METABOLISM NOT REQUIRED FOR:
Answer
  • acquisition and utilisation of energy
  • synthesis of molecules needed for cell structure and function
  • growth and development
  • binding of a hormone to a receptor

Question 33

Question
WHICH ONE OF THE FOLLOWING STATEMENTS IS TRUE FOR THE SYMPATHETIC NERVOUS SYSTEM?
Answer
  • It prepares us for strenuous muscular activity
  • It prepares us for relaxing (non-strenuous) activity
  • It is one of 3 autonomic nervous systems
  • It is a part of the endocrine system

Question 34

Question
CALCITONIN IS A HORMONE WHICH IS RELEASED FROM THE:
Answer
  • Thyroid gland
  • Parathyroid gland
  • Pituitary gland
  • Pancreas

Question 35

Question
DIABETES INSIPIDUS IS CAUSED BY:
Answer
  • A lack of insulin
  • A lack of ADH
  • A lack of oxytocin
  • An excess of insulin

Question 36

Question
PHOSPHOFRUCTOKINASE-1 ACTIVITY IS:
Answer
  • stimulated by citrate
  • inhibited by AMP
  • inhibited by citrate
  • inhibited by fructose 2,6-bisphosphate

Question 37

Question
GLYCOGEN SYNTHASE ACTIVITY IS:
Answer
  • inhibited by ATP
  • stimulated by fructose 2,6-bisphosphate inhibited by AMP
  • stimulated by fructose 1,6-bisphosphate
  • inhibited by AMP

Question 38

Question
THE RAISED LEVELS OF LACTIC ACID IN MUSCLES AFTER ANAEROBIC EXERCISE IS:
Answer
  • caused by an increase in ATP levels in the muscle cell
  • caused by an increase in AMP levels in the muscle cell
  • due to pyruvate being oxidised by lactate dehydrogenase to allow recycling of NAD+ to NADH
  • due to pyruvate being reduced by lactate dehydrogenase to allow recycling of NADH to NAD+

Question 39

Question
PROTEIN KINASE A:
Answer
  • is activated by 5'AMP
  • phosphorylates glycogen phosphorylase
  • is activated by cyclic AMP
  • phosphorylates fructose bisphosphatase-1

Question 40

Question
THE GLYCEROL PHOSPHATE SHUTTLE:
Answer
  • is responsible for transferring NADH from the cytosol to the mitochondrion matrix
  • is responsible for transferring ATP from the cytosol to the mitochondrion matrix
  • transfers reducing potential from cytosolic NADH to the mitochondrion
  • transfers reducing potential from cytosolic ATP to the mitochondrion
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