Biochemistry MCQ's

Question 1

Question

The redox centre of FAD is

Answer

Flavin mononucleotide (FMN)
Nicotinamide
Adenosine
Phosphate

Question 2

Question

Which of the following nucleotide triphosphates is often involved in signal transduction and also provides the energy for ribosomal translocation?

Answer

Question 3

Question

Which monosaccharide provides the main source of energy for sperm cells?

Answer

Glucose
Fructose
Galactose
Mannose

Question 4

Question

Which pathway(s) include phosphorylated seven carbon monosaccharides?

Answer

Calvin cycle
Leloir pathway
Glycogen synthesis
All of the above

Question 5

Question

The isomerisation of glucose 1-phosphate to glucose 6-phosphate occurs in which two pathways?

Answer

Calvin cycle and glycogen synthesis
Leloir pathway and Calvin cycle
Leloir pathway and glycolysis
Leloir pathway and glycogen synthesis

Question 6

Question

Steroids

Answer

Are entirely hydrophobic molecules
Often act as hormones
Cannot pass through cell membranes
Are mainly hydrophilic molecules

Question 7

Question

The sequence of reactions: oxidation-hydration-oxidation occurs in which two pathways?

Answer

β-oxidation of fatty acids and tricarboxylic acid (Krebs’) cycle
β-oxidation of fatty acids and glycolysis
Fatty acid synthesis and tricarboxylic acid (Krebs’) cycle
Fatty acid synthesis and glycolysis

Question 8

Question

The mobility of membrane phospholipids can be demonstrated by

Answer

Irradiating a leaf and watching the return of the green colour
Observing the molecules using an electron microscope
Paper chromatography of the lipids and staining
Bleaching of fluorescently labelled phospholipids and watching the return of the fluorescence

Question 9

Question

Cholesterol is an example of what class of molecule?

Answer

Sterol
Fatty acid
Ketose monosaccharide
Aldose monosaccharide

Question 10

Question

In the Calvin cycle, how many molecules of carbon dioxide are required for the synthesis of one molecule of fructose 6-phosphate?

Answer

Question 11

Question

In cellulose, the glucose residues are bonded together by:

Answer

α(1→4) glycosidic bonds
α(1→4) glycosidic bonds with α(1→6) glycosidic bonds approximately every tenth residue
β(1→4) glycosidic bonds
β(1→4) glycosidic bonds with β(1→6) glycosidic bonds approximately every tenth residue

Question 12

Question

Which of the following is not a reducing sugar?

Answer

Sucrose
Maltose
Lactose
Galactose

Question 13

Question

The carnitine cycle

Answer

“Fixes” atmospheric carbon dioxide into sugars
Transports fatty acids into the matrix of the mitochondria
Transports ATP out of the mitochondria
Produces NADH for use in oxidative phosphorylation

Question 14

Question

Glycerol can be used as a source of energy by conversion to the glycolytic intermediate dihydroxyacetone phosphate. Per molecule of glycerol, this process:

Answer

Produces one molecule of NADH and consumes one molecule of ATP
Produces one molecule of ATP and consumes one molecule of NADH
Produces one molecule of NADH and consumes no molecules of ATP
Produces no molecules of NADH and consumes one molecule of ATP

Question 15

Question

Fatty acid synthesis:

Answer

Requires NADH
Requires water as a reactant
Adds carbon atoms two at a time
All of the above

Question 16

Question

In enzyme kinetics, the ratio of constants kcat/Km:

Answer

Is a measure of the rate of acceleration carried out by the enzyme.
For a given enzyme is independent of the substrate used.
Has units of concentration.
Gives an idea of the enzymes catalytic efficiency.

Question 17

Question

In enzyme catalysis, the term ‘approximation’ refers to:

Answer

A catalytic strategy facilitating transition state formation through covalent bond formation between the substrate and enzyme active site.
A catalytic strategy facilitating transition state formation through hydrogen bond formation and electrostatic bond formation between the substrate and enzyme active site.
A catalytic strategy facilitating transition state formation through interaction involving metal ions and substrate in the enzyme active site.
A catalytic strategy facilitating transition state formation through direct transfer of a proton to or from the substrate in the enzyme active site.

Question 18

Question

Consider an enzyme that shows Michaelis-Menten kinetics where: v0 = Vmax . [S] / (Km + [S]) If a substrate, S, is present at a concentration of 8 mM, and Km is 4 mM, the rate of reaction (v0) measured will be:

Answer

Half of Vmax
Two thirds of Vmax
Double Vmax
Three times Vmax

Question 19

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 20

Question

Enzymes:

Answer

are chemically altered at the end of their reaction
are involved in changing the equilibrium constant of the reaction that they catalyse
bind their substrates at their active site(s)
increase the activation energy of the reaction they catalyse

Question 21

Question

The Michaelis constant, Km:

Answer

Is a measure of the rate acceleration caused by the enzyme
For a given enzyme is independent of the substrate used
Has units of concentration
Gives an idea of the enzyme’s catalytic efficiency

Question 22

Question

The Vmax of an enzyme catalysed reaction:

Answer

Is altered when a competitive inhibitor is present
Can be determined from the intercept on the x-axis of a Lineweaver-Burk plot
Is the maximum rate at which the enzyme can convert substrate into product
Has units of concentration

Question 23

Question

Proteosome-mediated proteolysis:

Answer

Is controlled by serine protease enzymes.
Is a key part of the control mechanism in the eukaryote cell cycle
Is a key part of the control mechanism in the prokaryote cell cycle
Is controlled by ubiquinone activating enzymes.

Question 24

Question

The Alanine Cycle:

Answer

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 located in the cell membrane of muscle cells.

Question 25

Question

Which of the following is a Redox Centre of Mitochondrial Respiratory Chain Enzymes?

Answer

NADPH
Succinate
Oxygen
FMN, flavin

Question 26

Question

In Photosynthesis energy of light Quanta is captured by a molecule of:

Answer

Plastoquinone
Oxygen
Chlorophyll
Cytochrome c

Question 27

Question

What is the overall equation for a light phase of Photosynthesis?

Answer

18CO2+ 2 NADPH + 3 ATP + light → 2 NADPH + 3 Glucose + 3 ADP + 18O2
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

Question 28

Question

Uncouplers inhibit Mitochondrial Oxidative Phosphorylation due to:

Answer

Inhibition of respiratory chain
Their ability to translocate protons and dissipate the membrane potential
Inhibition of ATP-hydrolysis
Inhibition of glycolysis

Question 29

Question

Which of the following statements about light phase of Photosynthesis is incorrect?

Answer

Proton-translocating ATP-synthase of thylakoid membrane can synthesise ATP
Photosystem I and II can capture light quanta
The thylakoid membrane is negatively charged on the lumen side
The proton motive force can be used for active transport

Question 30

Question

In biochemical pathways the metabolic cycles are:

Answer

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

Question 31

Question

Protein degradation is an example of which type of biochemical pathway?

Answer

Anabolic
Catabolic
Amphibolic
Hyperbolic

Question 32

Question

Which of the following is true of endotherms?

Answer

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

Question 33

Question

Which ONE of the following statements are 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

Diabetes insipidus is a disease caused by:

Answer

A lack of insulin
A lack of ADH
A lack of oxytocin
An excess of insulin

Question 35

Question

Cyclic AMP is:

Answer

An activator of pyruvate kinase C
An activator of protein kinase A
The product of adenylate kinase
An activator of phosphofructokinase-1

Question 36

Question

Phosphofructokinase-1 Activity is:

Answer

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

Question 37

Question

Glycogen Phosphorylase is:

Answer

inhibited by AMP
activated by phosphorylation
activated by glucose
inhibited by phosphorylation

Question 38

Question

Protein Kinase A:

Answer

is an allosteric enzyme
is activated by ADP
phosphorylates glycogen phosphorylase
phosphorylates phosphorylase kinase

Question 39

Question

Cancer cells produce large amounts of Lactate even in the presence of Oxygen because they:

Answer

Lack mitochondria
Lack the gene for citrate synthase
Possess an over-active glycerol phosphate shuttle
Have a defective glycerol phosphate shuttle

Question 40

Question

We know relatively little about the metabolism of the liver fluke. What is the most realistic prediction about galactose metabolism in this organism compared to the one we know about in humans?

Answer

It will follow the Leloir pathway like in humans
It will follow a different pathway because it is a parasite
It will follow a different pathway because it eats different food
We cannot make any realistic predictions

	Created by tj.sloan almost 6 years ago

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Biochemistry MCQ's

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Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21

Question 22

Question 23

Question 24

Question 25

Question 26

Question 27

Question 28

Question 29

Question 30

Question 31

Question 32

Question 33

Question 34

Question 35

Question 36

Question 37

Question 38

Question 39

Question 40

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