Formative A 2017 Flashcards
1
Q
- The organic component of bone matrix is
produced by which one of the following cell types? - Chondroblasts
- Chondrocytes
- Osteoblasts
- Osteoclasts
- Osteocytes
A
- Osteoblasts
2
Q
- At which one the following locations does growth
occur in the length of the long bone? - Diaphysial plate
- Epiphysial plate
- Metaphysis
- Periosteum
- Primary ossification centre
A
- Epiphysial plate
3
Q
- In a relaxed skeletal muscle, the cross-bridges are
best described by which one of the following? - A complex of myosin, troponin, ATP, and Pi
- A high-energy complex of myosin, ADP, and Pi
- A myosin ATP complex
- Dissociated from the thick filaments
- Inhibited by tropomyosin
A
- Inhibited by tropomyosin
4
Q
- In pharmacology ED50 is defined by which one of
the following?
A. Comparison of the amount of a therapeutic agent that causes
the therapeutic effect to the amount that causes toxic effects
B. The amount of drug that produces a therapeutic response in half of the test group
C. The dose that kills half of the test group
D. The equilibrium dissociation constant, where the concentration
of free drug is at half-maximal binding
E. The maximum dose where toxicity is not observed
A
B. The amount of drug that produces a therapeutic response in half of the test group
5
Q
- Which one of the following best describes
properties of parasympathetic nerves? - Cause sweat secretion in the skin when body temperature rises
- Cause vasodilation in skeletal muscle during prolonged exercise
- Have longer postganglionic fibres than preganglionic fibres
- Have opposite effects to sympathetic nerves on intestinal smooth muscle
- Have opposite effects to sympathetic nerves on iris smooth
muscle
A
- Have opposite effects to sympathetic nerves on intestinal smooth muscle
6
Q
- Cholera toxin disrupts GPCR (G Protein Coupled Receptor) signalling by inhibiting the GTPase activity of a Gs protein alpha subunit in intestinal epithelial cells. Which one of the following is the most likely cellular response to this?
- Increased activity of adenyl cyclase
- Increased activity of phosphodiesterase
- Increased entry of steroid hormone receptors into the nucleus
- Increased formation of inactive G protein trimers
- Increased phosphorylation of the GPCR
A
- Increased activity of adenyl cyclase
7
Q
- Cilia are more likely to be found in which one of
the following types of epithelium? - Pseudo-stratified columnar
- Simple cuboidal
- Stratified columnar
- Stratified cuboidal
- Transitional
A
- Pseudo-stratified columnar
8
Q
- The thoracic wall is innervated by which one of
the following? - Dorsal primary rami
- Intercostal nerves
- Lateral pectoral nerves
- Medial pectoral nerves
- Thoracodorsal nerves
A
- Intercostal nerves
9
Q
- What happens to excess neurotransmitter
produced by a presynaptic neuron? - It is eliminated by enzymes secreted by the cell body
- It is reabsorbed up by the presynaptic neuron
- It is taken up by neighbouring capillaries
- It is taken up by the postsynaptic neuron
- It is taken up by both the presynaptic and postsynaptic neurons
A
- It is reabsorbed up by the presynaptic neuron
10
Q
- In which type of joint does a slightly flexible interosseous ligament bind the bones?
- Gomphosis
- Suture
- Symphesis
- Synchondrosis
- Syndesmosis
A
- Syndesmosis
11
Q
- In an anaerobic system that is metabolising
glucose, which one of the following compounds will
increase in concentration following the addition of
fluoride which inhibits enolase? - 2-phosphoglycerate
- Acetyl-CoA
- Glucose
- Phosphoenolpyruvate
- Pyruvate
A
- 2-phosphoglycerate
12
Q
- Muscarinic receptor agonists may induce
vasodilation largely by causing the release of which
one of the following by endothelial cells? - Acetylcholine
- Epinephrine
- Histamine
- Nitric oxide
- Norepinephrine
A
- Nitric oxide
13
Q
- A blistering disease resulting from a genetic
defect in a component of desmosomes will have
which one of the following effects on the skin? - A decrease in the elasticity of the skin
- A decrease in the water permeability of the skin
- Separation of the epidermis from the dermis
- Separation between the layers of keratinocytes in the stratum spinosum
- Separation of the stratum corneum from the underlying layers of
the epidermis
A
- Separation between the layers of keratinocytes in the stratum spinosum
14
Q
- Which one of the following is mostly found inside
the epiphyses of each long bone? - Cartilage
- Compact bone
- Endosteum
- Spongy bone
- Yellow marrow
A
- Spongy bone
15
Q
- Which one of the following best describes the
crowns of the incisors when viewed from the
incisal? - Are wider mesiodistally than buccolingually in both arches
- Are wider buccolingually than mesiodistally in both arches
- Are wider mesiodistally in the maxilla, and wider buccolingually
in the mandible - Are wider buccolingually than mesiodistally in the maxilla
- Are wider mesiodistally in the mandible and wider mesiodistally
in the maxilla
A
- Are wider mesiodistally in the maxilla, and wider buccolingually
in the mandible
16
Q
- Which second messenger signals the release of
Ca2+ from endoplasmic reticulum? - 1,2 diacyl glycerol (DAG)
- cAMP
- cGMP
- Inositol triphosphate (IP3)
- Nitric oxide (NO)
A
- Inositol triphosphate (IP3)
17
Q
- Which one of the following is a class of receptors that
activate signalling pathways usually by forming molecular
dimers that result in protein phosphorylation reactions upon
binding of their specific ligand? - G protein-coupled receptors
- Ligand-gated ion channels
- Na+/Glucose symports
- Receptor tyrosine kinases
- Steroid hormone receptors
A
- Receptor tyrosine kinases
18
Q
- Which one of the following properties is shared
by all three of skeletal muscle cells, cardiac
autorhythmic cells, and cardiac contractile cells? - Ca2+ is involved in cell potentials
- Depolarization to threshold is caused primarily by K+ outflow
- Depolarization between threshold and peak membrane potential
is caused entirely by Na+ inflow - Repolarization is caused by K+ outflow
- The depolarization phase is longer than the repolarization phase
A
- Repolarization is caused by K+ outflow
19
Q
- Which one of the following correctly states a
difference between skeletal and smooth muscle
contraction? - Skeletal-muscle contraction requires the influx of extracellular
Ca2+, whereas smooth muscle contraction does not. - Skeletal-muscle contraction involves interactions between thick
and thin filaments, whereas smooth muscle contraction does
not. - Skeletal-muscle contraction results from cross-bridge cycling,
whereas smooth muscle contraction does not. - Skeletal muscle contraction requires release of Ca2+ from
sarcoplasmic reticulum, whereas smooth muscle contraction
does not. - Skeletal muscle contraction is regulated by calcium acting on the
thin filament, whereas in smooth muscle contraction it is on the
thick filament
A
- Skeletal muscle contraction is regulated by calcium acting on the
thin filament, whereas in smooth muscle contraction it is on the
thick filament
20
Q
- An noncompetitive inhibitor of an enzyme
catalysed reaction is best explained by which one of
the following? - Binds the the Michaelis complex (ES)
- Can normally be reversed by increasing substrate concentration
- Decreases Vmax
- Demonstrates sigmoid kinetic properties
- Increases Km
A
- Decreases Vmax
21
Q
- All of the following drugs produce either direct
or indirect parasympathomimetic effects, EXCEPT? - A beta-adrenoreceptor agonist (eg isoproterenol)
- A direct muscarinic agonist (eg bethanechol)
- A direct nicotinic agonist (eg nicotine)
- A muscarinic receptor antagonist (eg atropine)
- A reversible cholinesterase inhibitor (eg neostigmine)
A
- A beta-adrenoreceptor agonist (eg isoproterenol)
22
Q
- Which one of the following is PRESENT in bone
but LACKING in cartilage? - Abundant extracellular matrix
- Capillaries
- Collagen
- Lacunae
- Significant amounts of water surrounding cells
A
- Capillaries
23
Q
- Binding of acetylcholine to the nicotinic acetylcholine
receptor induces a conformational change which results in
which one of the following responses? - Activates a G protein.
- Activates autophosphorylation of the receptor
- Opens a transmembrane pore allowing Na+ and Ca2+ to flow
out of the cell. - Opens a transmembrane pore allowing Na+ and K+ to flow into the cell.
- Repolarisation of the plasma membrane of neurons due to
movement of cations
A
- Opens a transmembrane pore allowing Na+ and K+ to flow into the cell.
24
Q
- Depolymerization of microtubules is enhanced by
which one of the following? - Hydrolysis of ATP
- Hydrolysis of GTP
- Phosphorylation of alpha-tubulin subunits
- Phosphorylation of GDP
- Replacement of alpha-tubulin by beta-tubulin subunits
A
- Hydrolysis of GTP
25
Q
- What is the major driving force determining the
tertiary structure of a protein? - Covalent disulphide bridges
- Hydrogen bonding
- Hydrophobic forces
- Ionic interactions
- Van Der Waals forces
A
- Hydrophobic forces
26
Q
- Which nerve is endangered during surgical
removal of an impacted third mandibular molar
tooth? - Hypoglossal
- Glossopharyngeal
- Inferior alveolar
- Lingual
- Pterygopalatine ganglion
A
- Inferior alveolar
27
Q
- Which one of the following enzymes produces
free glucose molecules during the breakdown of
glycogen in the liver? - Debranching enzyme
- Glucokinase
- Glucose-6-phosphatase
- Glycogen phosphorylase
- Phosphorylase kinase
A
- Glucose-6-phosphatase
28
Q
- Nerve fibres of the sympathetic division of the
autonomic nervous system originate in which of the
following regions of the spinal cord? - Brainstem and sacral
- Cervical and thoracic
- Cervical, thoracic and lumbar
- Lumbar and sacral
- Thoracic and lumbar
A
- Thoracic and lumbar