The redox centre of FAD is
Flavin mononucleotide (FMN)
Nicotinamide
Adenosine
Phosphate
Which of the following nucleotide triphosphates is often involved in signal transduction and also provides the energy for ribosomal translocation?
CTP
TTP
UTP
GTP
Which monosaccharide provides the main source of energy for sperm cells?
Glucose
Fructose
Galactose
Mannose
Which pathway(s) include phosphorylated seven carbon monosaccharides?
Calvin cycle
Leloir pathway
Glycogen synthesis
All of the above
The isomerisation of glucose 1-phosphate to glucose 6-phosphate occurs in which two pathways?
Calvin cycle and glycogen synthesis
Leloir pathway and Calvin cycle
Leloir pathway and glycolysis
Leloir pathway and glycogen synthesis
Steroids
Are entirely hydrophobic molecules
Often act as hormones
Cannot pass through cell membranes
Are mainly hydrophilic molecules
The sequence of reactions: oxidation-hydration-oxidation occurs in which two pathways?
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
The mobility of membrane phospholipids can be demonstrated by
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
Cholesterol is an example of what class of molecule?
Sterol
Fatty acid
Ketose monosaccharide
Aldose monosaccharide
In the Calvin cycle, how many molecules of carbon dioxide are required for the synthesis of one molecule of fructose 6-phosphate?
3
4
6
12
In cellulose, the glucose residues are bonded together by:
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
Which of the following is not a reducing sugar?
Sucrose
Maltose
Lactose
The carnitine cycle
“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
Glycerol can be used as a source of energy by conversion to the glycolytic intermediate dihydroxyacetone phosphate. Per molecule of glycerol, this process:
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
Fatty acid synthesis:
Requires NADH
Requires water as a reactant
Adds carbon atoms two at a time
In enzyme kinetics, the ratio of constants kcat/Km:
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.
In enzyme catalysis, the term ‘approximation’ refers to:
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.
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:
Half of Vmax
Two thirds of Vmax
Double Vmax
Three times Vmax
Koshland’s induced fit model for enzyme-substrate complex formation:
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
Enzymes:
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
The Michaelis constant, Km:
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
The Vmax of an enzyme catalysed reaction:
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
Proteosome-mediated proteolysis:
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.
The Alanine Cycle:
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.
Which of the following is a Redox Centre of Mitochondrial Respiratory Chain Enzymes?
NADPH
Succinate
Oxygen
FMN, flavin
In Photosynthesis energy of light Quanta is captured by a molecule of:
Plastoquinone
Chlorophyll
Cytochrome c
What is the overall equation for a light phase of Photosynthesis?
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
Uncouplers inhibit Mitochondrial Oxidative Phosphorylation due to:
Inhibition of respiratory chain
Their ability to translocate protons and dissipate the membrane potential
Inhibition of ATP-hydrolysis
Inhibition of glycolysis
Which of the following statements about light phase of Photosynthesis is incorrect?
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
In biochemical pathways the metabolic cycles are:
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
Protein degradation is an example of which type of biochemical pathway?
Anabolic
Catabolic
Amphibolic
Hyperbolic
Which of the following is true of endotherms?
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
Which ONE of the following statements are true for the sympathetic nervous system?
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
Diabetes insipidus is a disease caused by:
A lack of insulin
A lack of ADH
A lack of oxytocin
An excess of insulin
Cyclic AMP is:
An activator of pyruvate kinase C
An activator of protein kinase A
The product of adenylate kinase
An activator of phosphofructokinase-1
Phosphofructokinase-1 Activity is:
stimulated by citrate
inhibited by citrate
inhibited by AMP
inhibited by fructose 2,6-bisphosphate
Glycogen Phosphorylase is:
activated by phosphorylation
activated by glucose
inhibited by phosphorylation
Protein Kinase A:
is an allosteric enzyme
is activated by ADP
phosphorylates glycogen phosphorylase
phosphorylates phosphorylase kinase
Cancer cells produce large amounts of Lactate even in the presence of Oxygen because they:
Lack mitochondria
Lack the gene for citrate synthase
Possess an over-active glycerol phosphate shuttle
Have a defective glycerol phosphate shuttle
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?
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
