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

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Biochemistry MCQs- August 11

Question 1 of 40

1

IF WE WERE ABLE TO DETERMINE THE REACTIONS OF THE KREBS’ (TRICARBOXYLIC ACID) CYCLE FROM A WOOLLY MAMMOTH, WOULD YOU EXPECT THEM TO BE:

Select one of the following:

  • 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

Explanation

Question 2 of 40

1

AN END-PRODUCT CAN ACT TO INHIBIT AN ENZYME BY BINDING AT THE:

Select one of the following:

  • Transitional site

  • Active site

  • Activation site

  • Allosteric site

Explanation

Question 3 of 40

1

THE SINGLE BIGGEST SIDE-EFFECT OF INSULIN THERAPY IS:

Select one of the following:

  • A fear of needles

  • Hyperactivity

  • Hypoglycaemia

  • Hyperglycaemia

Explanation

Question 4 of 40

1

WHICH OF THE FOLLOWING IS A COMMON PHYSIOLOGICAL METHOD OF LOWERING BODY TEMPERATURE?

Select one of the following:

  • Stimulation of the mitochondria in brown fat cells

  • Rhythmic Stimulation of skeletal muscle

  • Increased thyroid gland activity

  • Accelerated respiration

Explanation

Question 5 of 40

1

WHICH OF THE FOLLOWING STATEMENTS CONCERNING ENZYME CASCADES IS FALSE?

Select one of the following:

  • 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

Explanation

Question 6 of 40

1

WHICH OF THE FOLLOWING STATEMENTS CONCERNING STEROID HORMONES IS TRUE?

Select one of the following:

  • 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

Explanation

Question 7 of 40

1

THE ENZYME-SUBSTRATE COMPLEX:

Select one of the following:

  • 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.

Explanation

Question 8 of 40

1

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:

Select one of the following:

  • One third of Vmax

  • Three times Vmax

  • Three quarters of Vmax

  • Six times Vmax

Explanation

Question 9 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 10 of 40

1

THE ENTHALPY CHANGE ASSOCIATED WITH A BIOCHEMICAL REACTION:

Select one of the following:

  • 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)

Explanation

Question 11 of 40

1

ENZYMES USUALLY UTILISE ONE OR MORE TRANSITION METAL ATOMS AT THE ACTIVE SITE TO:

Select one of the following:

  • Facilitate substrate binding

  • Facilitate transition state formation

  • Facilitate stabilisation of the tertiary structure

  • Facilitate conformational changes in the protein during the catalytic cycle

Explanation

Question 12 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 13 of 40

1

THE TRANSITION STATE IN AN ENZYME-CATALYSED REACTION:

Select one of the following:

  • 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.

Explanation

Question 14 of 40

1

SERINE PROTEASES:

Select one of the following:

  • 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

Explanation

Question 15 of 40

1

THE UBIQUITIN PROTEIN:

Select one of the following:

  • 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

Explanation

Question 16 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 17 of 40

1

THE MOST COMMON FORM OF FRUCTOSE IN SOLUTION IS:

Select one of the following:

  • A pyranose (six-membered) ring form

  • A furanose (five-membered) ring form

  • A straight chain, ketone form

  • A straight chain, aldehyde form

Explanation

Question 18 of 40

1

FATTY ACIDS:

Select one of the following:

  • 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

Explanation

Question 19 of 40

1

TESTOSTERONE IS:

Select one of the following:

  • A sterol

  • A ketose monosaccharide

  • A fatty acid

  • A cofactor

Explanation

Question 20 of 40

1

WHICH IF THESE MOLECULES IS COMMONLY INVOLVED IN CELL SIGNALLING AND RIBOSOMAL TRANSLOCATION?

Select one of the following:

  • TTP

  • CTP

  • UTP

  • GTP

Explanation

Question 21 of 40

1

THE PRECURSORS FOR THE BIOSYNTHESIS OF SUCROSE ARE:

Select one of the following:

  • UDP-glucose and fructose 6-phosphate

  • UDP-fructose and glucose 6-phosphate

  • UDP-glucose and fructose

  • UDP-fructose and glucose

Explanation

Question 22 of 40

1

TO DETERMINE THE IDENTITIES OF THE COMPOUNDS IN THE CALVIN CYCLE, MELVIN CALVIN USED:

Select one of the following:

  • Nuclear magnetic resonance spectroscopy and chemical analysis

  • Paper chromatography and mass spectrometry

  • Paper chromatography and chemical analysis

  • Chemical analysis and mass spectrometry

Explanation

Question 23 of 40

1

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?

Select one of the following:

  • It is not possible to know this from the information provided

  • Dihydroxyacetone phosphate

  • The equilibrium is approximately equally balanced

  • Glyceraldehyde 3-phosphate

Explanation

Question 24 of 40

1

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?

Select one of the following:

  • Reaction 1

  • Reaction 2

  • They both occur at much the same rate

  • It is not possible to know this from the data provided

Explanation

Question 25 of 40

1

IN GLYCOLYSIS, THE CONVERSION OF PHOSPHOENOLPYRUVATE TO PYRUVATE IS COUPLED TO:

Select one of the following:

  • 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+

Explanation

Question 26 of 40

1

IN YEAST UNDER ANAEROBIC CONDITIONS, ETHANOL IS PRODUCED AT THE END OF THE GLYCOLYTIC PATHWAY. WHY IS THIS ADVANTAGEOUS TO THE YEAST?

Select one of the following:

  • 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

Explanation

Question 27 of 40

1

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?

Select one of the following:

  • 6

  • 4

  • 2

  • 0

Explanation

Question 28 of 40

1

LACTOSE IS A DISACCHARIDE OF:

Select one of the following:

  • Glucose and mannose

  • Mannose and fructose

  • Galactose and fructose

  • Glucose and galactose

Explanation

Question 29 of 40

1

THE COFACTOR FAD (FLAVIN ADENINE DINUCLEOTIDE) IS COMPOSED OF WHICH SUBUNITS?

Select one of the following:

  • 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

Explanation

Question 30 of 40

1

NADPH IS USED IN THE CALVIN CYCLE TO:

Select one of the following:

  • Oxidise 1,3-bisphosphoglycerate

  • Reduce 1,3-bisphosphoglycerate

  • Oxidise ribulose 1,5-bisphosphate

  • Reduce ribulose 1,5-bisphosphate

Explanation

Question 31 of 40

1

IN GLUCONEOGENESIS, THE CORRECT SEQUENCE OF COMPOUNDS IN THE CONVERSION OF PYRUVATE TO PHOSPHOENOLPYRUVATE IS:

Select one of the following:

  • Pyruvate → Oxaloacetate → Phosphoenolpyruvate

  • Pyruvate → Lactate → Phosphoenolpyruvate

  • Pyruvate → Succinate → Phosphoenolpyruvate

  • Pyruvate → 1,3-bisphosphoglycerate → Phosphoenolpyruvate

Explanation

Question 32 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 33 of 40

1

GLYCOGEN PHOSPHORYLASE IS:

Select one of the following:

  • inhibited by phosphorylation

  • activated by phosphorylation

  • activated by glucose

  • inhibited by AMP

Explanation

Question 34 of 40

1

PROTEIN KINASE A:

Select one of the following:

  • is an allosteric enzyme

  • phosphorylates phosphorylase kinase

  • phosphorylates glycogen phosphorylase

  • is activated by ADP

Explanation

Question 35 of 40

1

ADRENALINE:

Select one of the following:

  • induces glycogen synthesis in the liver

  • induces gluconeogenesis in the liver

  • accelerates glyconeogenesis in the heart

  • inhibits glycolysis in the heart

Explanation

Question 36 of 40

1

GLYCOGEN PHOSPHORYLASE KINASE

Select one of the following:

  • is activated by cAMP

  • is activated by dephosphorylation

  • is activated by autophosphorylation

  • is activated by protein kinase A

Explanation

Question 37 of 40

1

WHAT IS THE SOURCE OF ENERGY FOR ATP SYNTHESIS IN MITOCHONDRIA?

Select one of the following:

  • ADP and inorganic phosphate

  • Gradient of NADH across the inner mitochondrial membrane

  • Matrix aconitase

  • None of the above

Explanation

Question 38 of 40

1

WHAT IS THE OVERALL EQUATION FOR PHOTOSYNTHESIS?

Select one of the following:

  • 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

Explanation

Question 39 of 40

1

WHICH OF THE FOLLOWING IS NOT A REDOX CENTRE FOR RESPIRATORY CHAIN?

Select one of the following:

  • NADH

  • Cytochrome c

  • Oxygen

  • FADH2

Explanation

Question 40 of 40

1

THE OXYGEN MOLECULES RELEASED INTO THE AIR AS A PRODUCT OF PHOTOSYNTHESIS COMES FROM:

Select one of the following:

  • Light quanta

  • Cytochome c oxidase

  • Water

  • Carbon dioxide

Explanation

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