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Quiz on Biochemistry MCQs- JUNE 09, created by MatthewEllis96 on 03/02/2015.

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Biochemistry MCQs- JUNE 09

Question 1 of 40

1

THE CARBOHYDRATE RIBOSE CONTAINS HOW MANY CARBON ATOMS?

Select one of the following:

  • 3

  • 4

  • 5

  • 6

Explanation

Question 2 of 40

1

SUCROSE IS A DISACCHARIDE OF:

Select one of the following:

  • Glucose and fructose

  • Maltose and glucose

  • Glucose and galactose

  • Fructose and galactose

Explanation

Question 3 of 40

1

THE BEST DESCRIPTION FOR FATTY ACIDS IS:

Select one of the following:

  • Hydrophobic

  • Hydrophilic

  • Amphipathic

  • Anglophobic

Explanation

Question 4 of 40

1

GLYCOGEN CONTAINS WHICH TYPES OF GLYCOSIDIC BONDS BETWEEN GLUCOSE RESIDUES?

Select one of the following:

  • α(1→4) and α(1→6)

  • β(1→4) and α(1→6)

  • α(1→4) and β(1→6)

  • β(1→4) and β(1→6)

Explanation

Question 5 of 40

1

THE CONFORMATION OF THE POLYSACCHARIDE CHAINS IN CELLULOSE IS NORMALLY:

Select one of the following:

  • Helical

  • Random coil

  • Zig-zag

  • Linear

Explanation

Question 6 of 40

1

THE REDOX CENTRE IN NAD+ IS:

Select one of the following:

  • Nicotine

  • Nicotinamide

  • Flavin mononucleotide

  • Flavinoid

Explanation

Question 7 of 40

1

WHICH NUCLEOTIDE TRIPHOSPHATE IS COMMONLY INVOLVED IN RIBOSOMAL TRANSLOCATION AND SIGNAL TRANSDUCTION?

Select one of the following:

  • CTP

  • TTP

  • UTP

  • GTP

Explanation

Question 8 of 40

1

IN LIVING CELLS, ATP IS USUALLY FOUND IN COMPLEX WITH WHICH ION?

Select one of the following:

  • Na+

  • Ca2+

  • Hg2+

  • Mg2+

Explanation

Question 9 of 40

1

IN THE LELOIR PATHWAY OF GALACTOSE METABOLISM, GALACTOSE IS PHOSPHORYLATED TO GIVE:

Select one of the following:

  • Galactose 1-phosphate

  • Galactose 6-phosphate

  • Glucose 1-phosphate

  • Glucose 6-phosphate

Explanation

Question 10 of 40

1

THE MAIN CARBOHYDRATE “FUEL” OF SPERM CELLS IS:

Select one of the following:

  • Glucose

  • Galactose

  • Fructose

  • Maltose

Explanation

Question 11 of 40

1

WHICH PATHWAY RESULTS IN THE GREATEST OVERALL DIRECT GENERATION OF ATP UNDER AEROBIC CONDITIONS?

Select one of the following:

  • Glycolysis

  • The tricarboxylic acid (Krebs) cycle

  • Oxidative phosphorylation

  • Gluconeogenesis

Explanation

Question 12 of 40

1

FOR THE COMPLETE OXIDATIVE METABOLISM OF ONE MOLECULE OF GLUCOSE UNDER AEROBIC CONDITIONS, HOW MANY TIMES DOES THE TRICARBOXYLIC ACID CYCLE “TURN”?

Select one of the following:

  • 0

  • 1

  • 2

  • 4

Explanation

Question 13 of 40

1

FOR EACH MOLECULE OF ACETYL COENZYME A (AcCoA) WHICH ENTERS THE TRICARBOXYLIC ACID CYCLE, HOW MANY MOLECULES OF CARBON DIOXIDE ARE RELEASED?

Select one of the following:

  • 0

  • 1

  • 2

  • 4

Explanation

Question 14 of 40

1

UNDER ANAEROBIC CONDITIONS, YEAST METABOLISE GLUCOSE TO:

Select one of the following:

  • Ethanol via acetic acid

  • Acetic acid via ethanol

  • Acetaldehyde (ethanal) via ethanol

  • Ethanol via acetaldehyde (ethanal)

Explanation

Question 15 of 40

1

THE PRODUCTS OF THE LIGHT REACTIONS OF PHOTOSYNTHESIS IN GREEN PLANTS INCLUDE:

Select one of the following:

  • NADH, oxygen and a proton motive force

  • NADPH, water and an electromotive force

  • NADPH, oxygen and a proton motive force

  • NADH, oxygen and an electromotive force

Explanation

Question 16 of 40

1

THE “DARK” REACTIONS OF PHOTOSYNTHESIS IN GREEN PLANTS REQUIRE:

Select one of the following:

  • NADPH, ATP and carbon dioxide

  • NAD+, ATP and carbon dioxide

  • NADPH, ADP and oxygen

  • NADPH, ATP and oxygen

Explanation

Question 17 of 40

1

TWO METHODOLOGIES USED BY MELVIN CALVIN TO ELUCIDATE THE “DARK” REACTIONS OF PHOTOSYNTHESIS WERE:

Select one of the following:

  • Paper chromatography and synthetic organic chemistry

  • X-ray crystallography and titrations

  • Gene sequencing and fluorescence resonance energy transfer

  • Tissue culture and NMR spectroscopy

Explanation

Question 18 of 40

1

WHICH OF THESE COFACTORS IS NEEDED FOR THE SYNTHESIS OF MALONYL COENZYME A FROM ACETYL COENZYME A AND CARBON DIOXIDE?

Select one of the following:

  • Niacin

  • NAD+

  • Thiamine

  • Biotin

Explanation

Question 19 of 40

1

IN WATER, FATTY ACIDS CAN SPONTANEOUSLY ASSEMBLE INTO WHAT STRUCTURES?v

Select one of the following:

  • Micelles

  • Mitochondria

  • Mitotic spindles

  • Myosin

Explanation

Question 20 of 40

1

MALONATE INHIBITS AN ENZYME IN WHICH METABOLIC PATHWAY?

Select one of the following:

  • Glycolysis

  • Tricarboxylic acid cycle

  • Leloir pathway

  • Glycogen biosynthesis

Explanation

Question 21 of 40

1

THE MICHAELIS CONSTANT, Km:

Select one of the following:

  • Has units of concentration

  • For a given enzyme is independent of the substrate used

  • Is a measure of the rate of acceleration carried out by the enzyme

  • Gives an idea of the enzyme’s catalytic efficiency

Explanation

Question 22 of 40

1

WHEN CONSIDERING ENZYME CATALYTIC MECHANISMS, ACID-BASE CATALYSIS:

Select one of the following:

  • Is usually dependant upon hydrogen bonding with at least one amino acid side chain at the active site to facilitate formation of the transition state

  • Is usually dependant upon hydrogen bonding between the carbonyl and amide groups of peptide bonds to facilitate formation of the transition state

  • Is usually dependant upon hydrogen bonding between a water molecule and the substrate to facilitate formation of the transition state

  • Is usually dependant upon hydrogen bonding with an oxidised metal ion prosthetic group in the active site to facilitate formation of the transition state

Explanation

Question 23 of 40

1

IN ENZYME CATALYSIS THE TERM “APPROXIMATION” REFERS TO:

Select one of the following:

  • 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

Explanation

Question 24 of 40

1

AN OXYANION HOLE IS:

Select one of the following:

  • 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

Explanation

Question 25 of 40

1

THE PROTEIN UBIQUITIN:

Select one of the following:

  • Can be covalently linked to proteins via the N-terminal 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

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 27 of 40

1

IN MICHAELIS-MENTON KINETICS, FORMATION OF THE ENZYME-SUBSTRATE COMPLEX:

Select one of the following:

  • Is always the rate limiting step in an enzyme catalysed reaction

  • Is never the rate limiting step in an enzyme catalysed reaction

  • Is always a necessary pre-requisite to formation of the transition state and therefore product turnover

  • Is never a necessary pre-requisite to formation of the transition state and therefore product turnover

Explanation

Question 28 of 40

1

THE TRANSITION STATE MODEL FOR ENZYME CATALYSIS:

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 29 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 30 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 31 of 40

1

FRUCTOSE 2,6-BISPHOSPHATE IS:

Select one of the following:

  • A glycolytic intermediate

  • The precursor of glyceraldehyde 3-phosphate and dihydroxyacetone phosphate

  • Produced from fructose 2-phosphate

  • A second messenger

Explanation

Question 32 of 40

1

THE BUILD UP OF LACTIC ACID IN MUSCLES AFTER ANAEROBIC EXERCISE IS:

Select one of the following:

  • Caused by an excess of ATP in the cytoplasm

  • Due to its synthesis being coupled to ATP hydrolysis

  • Due to pyruvate being reduced by lactate dehydrogenase to allow recycling of NADH to NAD+

  • Due to pyruvate being oxidised by lactate dehydrogenase to allow recycling of NAD+ to NADH

Explanation

Question 33 of 40

1

THE INCREASE IN ATP LEVELS THAT ACCOMPANIES THE "PASTEUR EFFECT" CAUSES:

Select one of the following:

  • 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

Explanation

Question 34 of 40

1

PROTEIN KINASE A IS ACTIVATED BY:

Select one of the following:

  • 5'-AMP

  • cAMP

  • ADP

  • NADH

Explanation

Question 35 of 40

1

THE WARBURG EFFECT IS:

Select one of the following:

  • The term used to describe the inhibition of glycolysis in anaerobic cells that occurs when oxygen is supplied

  • Caused (in some cancers) by a defect in the glycerol phosphate shuttle

  • Caused by an over-active glycerol phosphate shuttle in cancer

  • Due to the inhibition of phosphofructokinase-1 by NADH

Explanation

Question 36 of 40

1

THE RENIN-ANGIOTENSIN SYSTEM HELPS REGULATE:

Select one of the following:

  • Body fluids

  • Blood pressure

  • Body temperature

  • Breathing

Explanation

Question 37 of 40

1

WHICH OF THE FOLLOWING IS TRUE OF ECTOTHERMS?

Select one of the following:

  • They generate most of their heat through internal processes

  • They get most of their heat from the environment

  • They generate most of their heat from external processes

  • They cannot regulate their body temperature

Explanation

Question 38 of 40

1

IN BIOCHEMICAL PATHWAYS THE COMMON INTERMEDIATES ARE:

Select one of the following:

  • Initial substrates which feed into metabolic pathways

  • Compounds which catalyse the individual steps in a metabolic pathway

  • Compounds which occur at cross-over or branching points in metabolic pathways

  • Metabolic hubs which allow the use and re-use of relatively small numbers of molecules

Explanation

Question 39 of 40

1

THE KREBS (OR TCA) CYCLE IS AN EXAMPLE OF WHICH TYPE OF PATHWAY?

Select one of the following:

  • Anabolic

  • Catabolic

  • Amphibolic

  • Hyperbolic

Explanation

Question 40 of 40

1

WHICH OF THESE SYSTEMS IS MOST COMMON IN BIOLOGICAL SYSTEMS?

Select one of the following:

  • Positive feedback

  • Formative feedback

  • Negative feedback

  • Neutral feedback

Explanation

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