Formative A 2017

Question 1

1. The organic component of bone matrix is
   produced by which one of the following cell types?
2. Chondroblasts
3. Chondrocytes
4. Osteoblasts
5. Osteoclasts
6. Osteocytes

Answer 1

3. Osteoblasts

Question 2

6. At which one the following locations does growth
   occur in the length of the long bone?
7. Diaphysial plate
8. Epiphysial plate
9. Metaphysis
10. Periosteum
11. Primary ossification centre

Answer 2

2. Epiphysial plate

Question 3

8. In a relaxed skeletal muscle, the cross-bridges are
   best described by which one of the following?
9. A complex of myosin, troponin, ATP, and Pi
10. A high-energy complex of myosin, ADP, and Pi
11. A myosin ATP complex
12. Dissociated from the thick filaments
13. Inhibited by tropomyosin

Answer 3

5. Inhibited by tropomyosin

Question 4

9. 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

Answer 4

B. The amount of drug that produces a therapeutic response in half of the test group

Question 5

10. Which one of the following best describes
    properties of parasympathetic nerves?
11. Cause sweat secretion in the skin when body temperature rises
12. Cause vasodilation in skeletal muscle during prolonged exercise
13. Have longer postganglionic fibres than preganglionic fibres
14. Have opposite effects to sympathetic nerves on intestinal smooth muscle
15. Have opposite effects to sympathetic nerves on iris smooth
    muscle

Answer 5

4. Have opposite effects to sympathetic nerves on intestinal smooth muscle

Question 6

13. 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?
14. Increased activity of adenyl cyclase
15. Increased activity of phosphodiesterase
16. Increased entry of steroid hormone receptors into the nucleus
17. Increased formation of inactive G protein trimers
18. Increased phosphorylation of the GPCR

Answer 6

1. Increased activity of adenyl cyclase

Question 7

14. Cilia are more likely to be found in which one of
    the following types of epithelium?
15. Pseudo-stratified columnar
16. Simple cuboidal
17. Stratified columnar
18. Stratified cuboidal
19. Transitional

Answer 7

1. Pseudo-stratified columnar

Question 8

15. The thoracic wall is innervated by which one of
    the following?
16. Dorsal primary rami
17. Intercostal nerves
18. Lateral pectoral nerves
19. Medial pectoral nerves
20. Thoracodorsal nerves

Answer 8

2. Intercostal nerves

Question 9

16. What happens to excess neurotransmitter
    produced by a presynaptic neuron?
17. It is eliminated by enzymes secreted by the cell body
18. It is reabsorbed up by the presynaptic neuron
19. It is taken up by neighbouring capillaries
20. It is taken up by the postsynaptic neuron
21. It is taken up by both the presynaptic and postsynaptic neurons

Answer 9

2. It is reabsorbed up by the presynaptic neuron

Question 10

17. In which type of joint does a slightly flexible interosseous ligament bind the bones?
18. Gomphosis
19. Suture
20. Symphesis
21. Synchondrosis
22. Syndesmosis

Answer 10

5. Syndesmosis

Question 11

14. 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?
15. 2-phosphoglycerate
16. Acetyl-CoA
17. Glucose
18. Phosphoenolpyruvate
19. Pyruvate

Answer 11

1. 2-phosphoglycerate

Question 12

20. Muscarinic receptor agonists may induce
    vasodilation largely by causing the release of which
    one of the following by endothelial cells?
21. Acetylcholine
22. Epinephrine
23. Histamine
24. Nitric oxide
25. Norepinephrine

Answer 12

4. Nitric oxide

Question 13

21. A blistering disease resulting from a genetic
    defect in a component of desmosomes will have
    which one of the following effects on the skin?
22. A decrease in the elasticity of the skin
23. A decrease in the water permeability of the skin
24. Separation of the epidermis from the dermis
25. Separation between the layers of keratinocytes in the stratum spinosum
26. Separation of the stratum corneum from the underlying layers of
    the epidermis

Answer 13

4. Separation between the layers of keratinocytes in the stratum spinosum

Question 14

24. Which one of the following is mostly found inside
    the epiphyses of each long bone?
25. Cartilage
26. Compact bone
27. Endosteum
28. Spongy bone
29. Yellow marrow

Answer 14

4. Spongy bone

Question 15

25. Which one of the following best describes the
    crowns of the incisors when viewed from the
    incisal?
26. Are wider mesiodistally than buccolingually in both arches
27. Are wider buccolingually than mesiodistally in both arches
28. Are wider mesiodistally in the maxilla, and wider buccolingually
    in the mandible
29. Are wider buccolingually than mesiodistally in the maxilla
30. Are wider mesiodistally in the mandible and wider mesiodistally
    in the maxilla

Answer 15

3. Are wider mesiodistally in the maxilla, and wider buccolingually
   in the mandible

Question 16

26. Which second messenger signals the release of
    Ca2+ from endoplasmic reticulum?
27. 1,2 diacyl glycerol (DAG)
28. cAMP
29. cGMP
30. Inositol triphosphate (IP3)
31. Nitric oxide (NO)

Answer 16

4. Inositol triphosphate (IP3)

Question 17

27. 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?
28. G protein-coupled receptors
29. Ligand-gated ion channels
30. Na+/Glucose symports
31. Receptor tyrosine kinases
32. Steroid hormone receptors

Answer 17

4. Receptor tyrosine kinases

Question 18

28. Which one of the following properties is shared
    by all three of skeletal muscle cells, cardiac
    autorhythmic cells, and cardiac contractile cells?
29. Ca2+ is involved in cell potentials
30. Depolarization to threshold is caused primarily by K+ outflow
31. Depolarization between threshold and peak membrane potential
    is caused entirely by Na+ inflow
32. Repolarization is caused by K+ outflow
33. The depolarization phase is longer than the repolarization phase

Answer 18

4. Repolarization is caused by K+ outflow

Question 19

40. Which one of the following correctly states a
    difference between skeletal and smooth muscle
    contraction?
41. Skeletal-muscle contraction requires the influx of extracellular
    Ca2+, whereas smooth muscle contraction does not.
42. Skeletal-muscle contraction involves interactions between thick
    and thin filaments, whereas smooth muscle contraction does
    not.
43. Skeletal-muscle contraction results from cross-bridge cycling,
    whereas smooth muscle contraction does not.
44. Skeletal muscle contraction requires release of Ca2+ from
    sarcoplasmic reticulum, whereas smooth muscle contraction
    does not.
45. Skeletal muscle contraction is regulated by calcium acting on the
    thin filament, whereas in smooth muscle contraction it is on the
    thick filament

Answer 19

5. Skeletal muscle contraction is regulated by calcium acting on the
   thin filament, whereas in smooth muscle contraction it is on the
   thick filament

Question 20

35. An noncompetitive inhibitor of an enzyme
    catalysed reaction is best explained by which one of
    the following?
36. Binds the the Michaelis complex (ES)
37. Can normally be reversed by increasing substrate concentration
38. Decreases Vmax
39. Demonstrates sigmoid kinetic properties
40. Increases Km

Answer 20

3. Decreases Vmax

Question 21

37. All of the following drugs produce either direct
    or indirect parasympathomimetic effects, EXCEPT?
38. A beta-adrenoreceptor agonist (eg isoproterenol)
39. A direct muscarinic agonist (eg bethanechol)
40. A direct nicotinic agonist (eg nicotine)
41. A muscarinic receptor antagonist (eg atropine)
42. A reversible cholinesterase inhibitor (eg neostigmine)

Answer 21

1. A beta-adrenoreceptor agonist (eg isoproterenol)

Question 22

38. Which one of the following is PRESENT in bone
    but LACKING in cartilage?
39. Abundant extracellular matrix
40. Capillaries
41. Collagen
42. Lacunae
43. Significant amounts of water surrounding cells

Answer 22

2. Capillaries

Question 23

40. Binding of acetylcholine to the nicotinic acetylcholine
    receptor induces a conformational change which results in
    which one of the following responses?
41. Activates a G protein.
42. Activates autophosphorylation of the receptor
43. Opens a transmembrane pore allowing Na+ and Ca2+ to flow
    out of the cell.
44. Opens a transmembrane pore allowing Na+ and K+ to flow into the cell.
45. Repolarisation of the plasma membrane of neurons due to
    movement of cations

Answer 23

4. Opens a transmembrane pore allowing Na+ and K+ to flow into the cell.

Question 24

41. Depolymerization of microtubules is enhanced by
    which one of the following?
42. Hydrolysis of ATP
43. Hydrolysis of GTP
44. Phosphorylation of alpha-tubulin subunits
45. Phosphorylation of GDP
46. Replacement of alpha-tubulin by beta-tubulin subunits

Answer 24

2. Hydrolysis of GTP

Question 25

42. What is the major driving force determining the tertiary structure of a protein? 1. Covalent disulphide bridges 2. Hydrogen bonding 3. Hydrophobic forces 4. Ionic interactions 5. Van Der Waals forces

Answer 25

3. Hydrophobic forces

Question 26

44. Which nerve is endangered during surgical removal of an impacted third mandibular molar tooth? 1. Hypoglossal 2. Glossopharyngeal 3. Inferior alveolar 4. Lingual 5. Pterygopalatine ganglion

Answer 26

3. Inferior alveolar

Question 27

46. Which one of the following enzymes produces free glucose molecules during the breakdown of glycogen in the liver? 1. Debranching enzyme 2. Glucokinase 3. Glucose-6-phosphatase 4. Glycogen phosphorylase 5. Phosphorylase kinase

Answer 27

3. Glucose-6-phosphatase

Question 28

48. Nerve fibres of the sympathetic division of the autonomic nervous system originate in which of the following regions of the spinal cord? 1. Brainstem and sacral 2. Cervical and thoracic 3. Cervical, thoracic and lumbar 4. Lumbar and sacral 5. Thoracic and lumbar

Answer 28

5. Thoracic and lumbar