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Quiz on Biochemistry MCQs- MAY 10, created by MatthewEllis96 on 03/02/2015.

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Biochemistry MCQs- MAY 10

Biochemistry MCQs- MAY 10

Question 1 of 40

1

WHICH OF THESE LISTS CONTAINS ONLY MONOSACCHARIDES?

Select one of the following:

  • Glucose, galactose, fructose

  • Sucrose, lactose, mannose

  • Glucose, galactose, lactose

  • Glucose, galactose, sucrose

Explanation

Question 2 of 40

1

STARCH IS SYNTHESISED BY:

Select one of the following:

  • Plants

  • Insects

  • Cancer cells

  • All of the above

Explanation

Question 3 of 40

1

WHICH FUNCTIONAL GROUPS ARE PRESENT IN THE STRAIGHT CHAIN FORM OF FRUCTOSE?

Select one of the following:

  • Aldehyde and amine

  • Amine and ketone

  • Ketone and alcohol

  • Amine and alcohol

Explanation

Question 4 of 40

1

FOR EACH MOLECULE OF GLUCOSE, WHAT IS THE NET GAIN OF ATP IN GLYCOLYSIS?

Select one of the following:

  • No molecules

  • 2 molecules

  • 4 molecules

  • 8 molecules

Explanation

Question 5 of 40

1

A DISEASE IS CAUSED BY MUTATIONS IN THE GENES ENCODING ENZYMES IN THE LELOIR PATHWAY. WHICH SUGAR WILL PATIENTS BE UNABLE TO METABOLISE?

Select one of the following:

  • Glucose

  • Galactose

  • Fructose

  • Mannose

Explanation

Question 6 of 40

1

PERIPHERAL MEMBRANE PROTEINS ARE:

Select one of the following:

  • Associated with integral membrane proteins

  • Covalently linked to lipid molecules

  • Always glycosylated

  • Inserted into the membrane such that they have residues exposed on both sides

Explanation

Question 7 of 40

1

THE STRUCTURE AND FUNCTION OF A METABOLIC ENZYME IS LIKELY TO BE:

Select one of the following:

  • Very different, even in closely related organisms

  • Similar in different mammals, but different between mammals and the bacteria living in their guts

  • Similar in all animals, but different in plants

  • Highly conserved through evolution by natural selection

Explanation

Question 8 of 40

1

THE CALVIN CYCLE (“DARK” REACTIONS OF PHOTOSYNTHESIS):

Select one of the following:

  • Uses sucrose and NADPH

  • Generates sucrose and NADPH

  • Uses sucrose and generates NADPH

  • Generates sucrose and uses NADPH

Explanation

Question 9 of 40

1

A SATURATED FATTY ACID WITH 18 CARBONS WILL BE OXIDISED BY β-OXIDATION TO GIVE:

Select one of the following:

  • 18 molecules of CoA

  • 18 molecules of acetyl-CoA

  • 9 molecules of CoA

  • 9 molecules of acetyl-CoA

Explanation

Question 10 of 40

1

WHICH OF THESE FATTY ACIDS IS LIKELY TO HAVE THE LOWEST MELTING TEMPERATURE?

Select one of the following:

  • An 18 carbon saturated fatty acid

  • An 18 carbon fatty acid with one double bond

  • A 16 carbon saturated fatty acid

  • A 16 carbon fatty acid with two double bonds

Explanation

Question 11 of 40

1

THE SUGAR RESIDUE IN ATP IS:

Select one of the following:

  • Ribose

  • Deoxyribose

  • Ribulose

  • Raffinose

Explanation

Question 12 of 40

1

THE CONVERSION OF GLYCERALDEHYDE 3-PHOSPHATE TO 1,3-BISPHOSPHOGLYCERATE IN GLYCOLYSIS REQUIRES:

Select one of the following:

  • ATP and NAD+

  • Inorganic phosphate ions (Pi) and NADH

  • Inorganic phosphate ions (Pi) and NAD+

  • ATP and NADH

Explanation

Question 13 of 40

1

IN MAMMALIAN CELLS UNDER ANAEROBIC CONDITIONS, THE CONVERSION OF PYRUVATE TO LACTATE REGENERATES WHICH MOLECULE?

Select one of the following:

  • NADH

  • NAD+

  • FAD

  • ATP

Explanation

Question 14 of 40

1

CONSIDER GLYCOLYSIS AND THE KREBS’ TRICARBOXYLIC ACID CYCLE TOGETHER. WHICH IS THE FIRST STEP WHICH RELEASES CARBON DIOXIDE?

Select one of the following:

  • Fructose 1,6-bisphosphate → Glyceraldehyde 3-phosphate + dihydroxyacetone phosphate

  • Pyruvate → Acetyl Coenzyme A

  • Citrate → Isocitrate

  • Isocitrate → α-ketoglutarate

Explanation

Question 15 of 40

1

THE DECARBOXYLATION OF ISOCITRATE TO PRODUCE α-KETOGLUTARATE IN THE KREBS’ TRICARBOXYLIC ACID CYCLE REQUIRES:

Select one of the following:

  • NADP+

  • NAD+

  • NADPH

  • NADH

Explanation

Question 16 of 40

1

THE SEQUENCE OF REACTIONS OXIDATION-HYDRATION-OXIDATION OCCURS IN WHICH TWO METABOLIC PATHWAYS?

Select one of the following:

  • Glycolysis and the Krebs’ tricarboxylic acid cycle

  • Fatty acid oxidation and glycolysis

  • Fatty acid oxidation and the Krebs’ tricarboxylic acid cycle

  • Fatty acid oxidation and the Leloir pathway

Explanation

Question 17 of 40

1

THE REACTION: PYRUVATE + CARBON DIOXIDE + ATP → OXALOACETATE + ADP + PI, WHICH IS CATALYSED BY THE ENZYME PYRUVATE CARBOXYLASE IS IMPORTANT IN WHICH TWO PROCESSES?

Select one of the following:

  • Replenishing the Krebs tricarboxylic acid cycle intermediates and gluconeogenesis

  • Glycolysis and gluconeogenesis

  • Gluconeogenesis and glycogen synthesis

  • Replenishing the Krebs tricarboxylic acid cycle intermediates and glycolysis

Explanation

Question 18 of 40

1

IN BIOCHEMICAL PATHWAYS THE PRECURSORS ARE:

Select one of the following:

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

  • Initial substrates which feed into metabolic pathways

  • Compounds which catalyse the individual steps in a metabolic pathway

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

Explanation

Question 19 of 40

1

PROTEIN BIOSYNTHESIS CYCLE IS AN EXAMPLE OF WHICH TYPE OF BIOCHEMICAL PATHWAY?

Select one of the following:

  • Anabolic

  • Catabolic

  • Amphibolic

  • Hyperbolic

Explanation

Question 20 of 40

1

WHICH OF THE FOLLOWING IS TRUE OF ENDOTHERMS?

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 21 of 40

1

PARATHYROID HORMONE HELPS REGULATE:

Select one of the following:

  • Body fluids

  • Blood calcium

  • Body temperature

  • Breathing

Explanation

Question 22 of 40

1

A COMMON MECHANISM FOR INHIBITING METABOLIC PATHWAYS IS:

Select one of the following:

  • A build up of substrates

  • A build up of end-products

  • Over-activation of enzymes

  • Synthesis of new enzymes

Explanation

Question 23 of 40

1

FRUCTOSE 2,6-BISPHOSPHATE:

Select one of the following:

  • Activates fructose bisphosphatase-1

  • Activates phosphofructokinase-1

  • Inhibits phosphofructokinase-2

  • Activates phosphofructokinase-2

Explanation

Question 24 of 40

1

ANAEROBIC MUSCLE CELLS PRODUCE LACTIC ACID TO RECYCLE:

Select one of the following:

  • NADH to NAD+ via the action of lactate dehydrogenase

  • NADH to NAD+ via the action of alcohol dehydrogenase

  • NAD+ to NADH via the action of lactate dehydrogenase

  • NAD+ to NADH via the action of alcohol dehydrogenase

Explanation

Question 25 of 40

1

OXYGENATION OF ANAEROBIC YEAST CULTURE INDUCES THE "PASTEUR EFFECT", WHICH IS CAUSED BY:

Select one of the following:

  • Allosteric inhibition of phosphofructokinase-1 by increased AMP levels

  • Allosteric inhibition of fructose 1,6-bisphosphatase by increased ATP levels

  • Allosteric inhibition of phosphofructokinase-1 by increased ATP levels

  • Allosteric stimulation of phosphofructokinase-1 by increased AMP levels

Explanation

Question 26 of 40

1

CYCLIC AMP IS:

Select one of the following:

  • An activator of pyruvate kinase

  • An activator of protein kinase A

  • The product of adenylate kinase

  • An activator of phosphofructokinase-1

Explanation

Question 27 of 40

1

CANCER CELLS PRODUCE LARGE AMOUNTS OF LACTATE EVEN IN THE PRESENCE OF OXYGEN BECAUSE THEY:

Select one of the following:

  • Lack mitochondria

  • Lack the gene for citrate synthase

  • Possess an over-active glycerol phosphate shuttle

  • Have a defective glycerol phosphate shuttle

Explanation

Question 28 of 40

1

WHEN CONSIDERING ENZYME CATALYTIC MECHANISMS, ACID-BASE CATALYSIS IS USUALLY DEPENDANT UPON:

Select one of the following:

  • Hydrogen bonding with at least one amino acid side chain at the active site to facilitate formation of the transition state.

  • Hydrogen bonding between the carbonyl and amide groups of peptide bonds to facilitate formation of the transition state.

  • Hydrogen bonding between a water molecule and the substrate to facilitate formation of the transition state.

  • Hydrogen bonding with an oxidised metal ion prosthetic group in the active site to facilitate formation of the transition state.

Explanation

Question 29 of 40

1

MULTIPLICATION OF UBIQUITIN TAGGING:

Select one of the following:

  • Inhibits proteosome-mediated protein degradation

  • Is essential for proteosome-mediated protein degradation

  • Enhances proteosome-mediated protein degradation

  • Has nothing to do with proteosome-mediated protein degradation

Explanation

Question 30 of 40

1

ENZYMES REDUCE THE:

Select one of the following:

  • Entropy associated with chemical reactions

  • Enthalpy associated with chemical reactions

  • Gibb’s free energy associated with chemical reactions

  • Activation energy associated with chemical reactions

Explanation

Question 31 of 40

1

THE TRANSITION STATE IN AN ENZYME-CATALYSED REACTION:

Select one of the following:

  • Is always covalently associated with the enzyme.

  • Is never covalently associated with the enzyme.

  • Can never be observed experimentally.

  • Can often be similar in structure to potent enzyme inhibitors.

Explanation

Question 32 of 40

1

THE ALANINE CYCLE:

Select one of the following:

  • 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.

Explanation

Question 33 of 40

1

KOSHLAND’S INDUCED FIT MODEL FOR ENZYME-SUBSTRATE COMPLEX FORMATION MAY EXPLAIN WHY:

Select one of the following:

  • Enzymes have particular substrate specificity.

  • Enzymes are able to catalyse chemical reactions that cannot be facilitated in any other way

  • Enzymes increase the rate of a reaction by reduction of the activation energy change for the reaction

  • Enzymes can effectively reduce the loss of energy from a chemical reaction as heat

Explanation

Question 34 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 35 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 36 of 40

1

IF THE ΔG°' OF THE REACTION A → B is –20 kJ/mol, WHAT WILL HAPPEN IN THE PRESENCE OF A SPECIFIC ENZYME UNDER STANDARD CONDITIONS?

Select one of the following:

  • The reaction will stop

  • The reaction will proceed spontaneously from B to A

  • The reaction will proceed spontaneously from A to B

  • The reaction will not occur spontaneously

Explanation

Question 37 of 40

1

WHICH OF THE FOLLOWING IS AN EXERGONIC PROCESS?

Select one of the following:

  • Biosynthesis of DNA

  • Glycolysis

  • Transport of protons by respiratory chain

  • Brain activity due to the thinking about this question

Explanation

Question 38 of 40

1

FOR THE FOLLOWING REACTION:
L-Malate + NAD+ → Oxaloacetate + NADH + H+ ΔG°' = +29.7 kJ/mol.
WHICH OF THE FOLLOWING STATEMENTS IS CORRECT?

Select one of the following:

  • This reaction can only occur in a cell in which NADH is converted to NAD+ by the respiratory chain

  • This reaction can only occur in a cell if it is coupled to another reaction for which ΔG°' is large and negative

  • This reaction may occur in cells at some concentrations of substrate and product

  • This reaction is energy-releasing

Explanation

Question 39 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

  • Redox potential is measured in volts

  • Oxygen reduction has the highest potential

  • The strongest oxidants have the most negative potential

Explanation

Question 40 of 40

1

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

Select one of the following:

  • Plastoquinol/plastoquinone

  • NADH/NAD+

  • H2O/½O2

  • Ferrocytochrome c/ferricytochrome c

Explanation

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