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Quiz on Biochemistry MCQs- MAY 11, created by MatthewEllis96 on 02/02/2015.

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Biochemistry MCQs- MAY 11

Biochemistry MCQs- MAY 11

Question 1 of 40

1

SUCROSE IS SYNTHESISED BY WHICH OF THESE GROUPS OF ORGANISMS?

Select one of the following:

  • Mammals

  • Birds

  • Bees

  • Trees

Explanation

Question 2 of 40

1

WHICH OF THE FOLLOWING LISTS CONTAINS ONLY ALDOSE, HEXOSE MONOSACCHARIDES?

Select one of the following:

  • Glucose, Fructose, Mannose

  • Sucrose, Fructose, Ribose

  • Mannose, Galactose, Glucose

  • Sucrose, Mannose, Glucose

Explanation

Question 3 of 40

1

WHICH IF THESE MOLECULES OR IONS WILL PASS MOST EASILY THROUGH A PHOSPHOLIPID BILAYER?

Select one of the following:

  • A sodium ion

  • Urea

  • A chloride ion

  • ATP

Explanation

Question 4 of 40

1

WHICH OF THE FOLLOWING CARBOHYDRATES IS COMMONLY USED AS THE ACTIVE INGREDIENT IN “FAKE TAN”?

Select one of the following:

  • Glyceraldehyde

  • Galactose

  • Ribose

  • Dihydroxyacetone

Explanation

Question 5 of 40

1

GLYCOGEN IS SYNTHESISED FROM WHICH PRECURSOR?

Select one of the following:

  • Glucose

  • UDP-glucose

  • Sucrose

  • Glucose 6-phosphate

Explanation

Question 6 of 40

1

IN THE FIRST REACTION OF THE LELOIR PATHWAY, GALACTOSE REACTS WITH ATP TO MAKE:

Select one of the following:

  • Galactose 1-phosphate

  • Galactose 2-phosphate

  • Galactose 4-phosphate

  • Galactose 6-phosphate

Explanation

Question 7 of 40

1

CONSIDER GLYCOLYSIS STARTING FROM GLUCOSE AND ENDING WITH PYRUVATE. WHAT IS THE NET GAIN OF ATP PER MOLECULE OF GLUCOSE?

Select one of the following:

  • No molecules

  • Two molecules

  • Four molecules

  • Six molecules

Explanation

Question 8 of 40

1

IN HUMANS, UNDER ANAEROBIC CONDITIONS, NADH PRODUCED IN GLYCOLYSIS IS REGENERATED BY THE REDUCTION OF WHICH COMPOUND TO LACTATE?

Select one of the following:

  • Acetyl Coenzyme A (AcCoA)

  • Pyruvate

  • Phosphoenolpyruvate

  • Ethanol

Explanation

Question 9 of 40

1

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?

Select one of the following:

  • ATP

  • Acetyl CoA

  • Pyruvate

  • Carbon dioxide (CO2)

Explanation

Question 10 of 40

1

AMYLOPECTIN, A COMPONENT OF STARCH CONTAINS GLUCOSE UNITS BONDED TOGETHER BY(1→4) GLYCOSIDIC LINKS AND WHAT OTHER LINKAGE?

Select one of the following:

  • α(1→2) glycosidic links

  • α(1→6) glycosidic links

  • β(1→2) glycosidic links

  • β(1→6) glycosidic links

Explanation

Question 11 of 40

1

MALONATE IS TOXIC BECAUSE:

Select one of the following:

  • 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

Explanation

Question 12 of 40

1

IN CALVIN‟S “LOLLIPOP” EXPERIMENT TO INVESTIGATE THE INTERMEDIATES IN THE CALVIN CYCLE, THE FUNCTION OF THE BOILING ETHANOL WAS:

Select one of the following:

  • 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

Explanation

Question 13 of 40

1

THE CALVIN CYCLE USES WHICH REDOX COFACTOR?

Select one of the following:

  • NADP+

  • NADPH

  • NAD+

  • NADH

Explanation

Question 14 of 40

1

FATTY ACIDS ARE CARRIED IN THE BLOOD LARGELY:

Select one of the following:

  • In aqueous solution, not in complex with any other molecules

  • In complex with carbohydrates

  • In complex with cholesterol

  • In complex with proteins

Explanation

Question 15 of 40

1

CHOLESTEROL:

Select one of the following:

  • 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

Explanation

Question 16 of 40

1

ENZYMES:

Select one of the following:

  • 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

Explanation

Question 17 of 40

1

KOSHLAND‟S INDUCED FIT MODEL FOR ENZYME-SUBSTRATE COMPLEX FORMATION:

Select one of the following:

  • 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

Explanation

Question 18 of 40

1

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:

Select one of the following:

  • Half of Vmax

  • Two thirds of Vmax

  • Double Vmax

  • Three times Vmax

Explanation

Question 19 of 40

1

THE ENZYME-SUBSTRATE COMPLEX:

Select one of the following:

  • 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

Explanation

Question 20 of 40

1

IN ACID-BASE CATALYSIS:

Select one of the following:

  • 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.

Explanation

Question 21 of 40

1

THE CATALYTIC EFFICIENCY OF AN ENZYME CATALYSED REACTION:

Select one of the following:

  • 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

Explanation

Question 22 of 40

1

THE TERM „APPROXIMATION‟ HAS A SPECIFIC MEANING IN ENZYME CATALYSIS. THIS IS BEST DESCRIBED AS:

Select one of the following:

  • 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.

Explanation

Question 23 of 40

1

PROTEOSOME-MEDIATED PROTEOLYSIS:

Select one of the following:

  • 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.

Explanation

Question 24 of 40

1

THE UREA CYCLE:

Select one of the following:

  • 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.

Explanation

Question 25 of 40

1

THE PROTEIN UBIQUITIN:

Select one of the following:

  • 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.

Explanation

Question 26 of 40

1

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?

Select one of the following:

  • 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.

Explanation

Question 27 of 40

1

WHICH OF THE FOLLOWING IS AN EXERGONIC PROCESS?

Select one of the following:

  • Biosynthesis of NADPH

  • Transport of protons by respiratory chain

  • Oxygen reduction by cytochromec oxidase

  • Brain activity due to the thinking about this question

Explanation

Question 28 of 40

1

WHICH OF THE FOLLOWING STATEMENTS ABOUT MIDPOINT REDOX POTENTIALS IS INCORRECT?

Select one of the following:

  • 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.

Explanation

Question 29 of 40

1

WHICH OF THE FOLLOWING REDOX COUPLE HAVE THE HIGHEST MIDPOINT REDOX POTENTIAL?

Select one of the following:

  • ubiquinol/ubiquinone

  • NADPH/NADP+

  • ferrocytochrome c/ferricytochrome c

  • H2O/½O2

Explanation

Question 30 of 40

1

WHICH OF THE FOLLOWING STATEMENTS ABOUT MITOCHONDRIAL ELECTRON TRANSPORT IS INCORRECT?

Select one of the following:

  • 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.

Explanation

Question 31 of 40

1

WITH RESPECT TO BIOCHEMICAL PATHWAYS „BRANCHING POINTS‟ ARE:

Select one of the following:

  • 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

Explanation

Question 32 of 40

1

WHICH ONE OF THE FOLLOWING IS METABOLISM NOT REQUIRED FOR:

Select one of the following:

  • acquisition and utilisation of energy

  • synthesis of molecules needed for cell structure and function

  • growth and development

  • binding of a hormone to a receptor

Explanation

Question 33 of 40

1

WHICH ONE OF THE FOLLOWING STATEMENTS IS TRUE FOR THE SYMPATHETIC NERVOUS SYSTEM?

Select one of the following:

  • 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

Explanation

Question 34 of 40

1

CALCITONIN IS A HORMONE WHICH IS RELEASED FROM THE:

Select one of the following:

  • Thyroid gland

  • Parathyroid gland

  • Pituitary gland

  • Pancreas

Explanation

Question 35 of 40

1

DIABETES INSIPIDUS IS CAUSED BY:

Select one of the following:

  • A lack of insulin

  • A lack of ADH

  • A lack of oxytocin

  • An excess of insulin

Explanation

Question 36 of 40

1

PHOSPHOFRUCTOKINASE-1 ACTIVITY IS:

Select one of the following:

  • stimulated by citrate

  • inhibited by AMP

  • inhibited by citrate

  • inhibited by fructose 2,6-bisphosphate

Explanation

Question 37 of 40

1

GLYCOGEN SYNTHASE ACTIVITY IS:

Select one of the following:

  • inhibited by ATP

  • stimulated by fructose 2,6-bisphosphate inhibited by AMP

  • stimulated by fructose 1,6-bisphosphate

  • inhibited by AMP

Explanation

Question 38 of 40

1

THE RAISED LEVELS OF LACTIC ACID IN MUSCLES AFTER ANAEROBIC EXERCISE IS:

Select one of the following:

  • 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+

Explanation

Question 39 of 40

1

PROTEIN KINASE A:

Select one of the following:

  • is activated by 5'AMP

  • phosphorylates glycogen phosphorylase

  • is activated by cyclic AMP

  • phosphorylates fructose bisphosphatase-1

Explanation

Question 40 of 40

1

THE GLYCEROL PHOSPHATE SHUTTLE:

Select one of the following:

  • 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

Explanation

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