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Dentistry Exam Questions > January Summative > Flashcards

January Summative Flashcards

1
Q

The organic component of bone matrix is produced by which of the following cell types?

1) Chondroblasts
2) Chondrocytes
3) Osteoblasts
4) Osteoclasts
5) Osteocytes

A

3

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2
Q

Glycoproteins and glycolipids, assembled in Golgi bodies are packaged for distribution in which of the following:

1) Cisternae
2) Glyoxysomes
3) Liposomes
4) Lysosomes
5) Peroxisomes

A

1

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3
Q

Which of the following is the correct isoelectric poit for the amino acid cysteine, assuming that the pKa values for this amin acid are, 1.7 for alpha carboxyl, 8.3 for side goup, 10.8 for alpha amino.

1) 1.72
2) 5.00
3) 6.25
4) 8.30
5) 9.55

A

2

Isoelectric point = no net charge (positive charge at amino and negative at carboxyl).
This is found at the midpoint between the first two pKa values.

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4
Q

At which one of the following does growth occur in the length of a long bone?

1) Diaphysial plate
2) Epiphyseal palte
3) Metaphysis
4) Periosteum
5) Primary Ossification Centre

A

2

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5
Q

In a relaxed skeletal muscle, the cross-bridges are best described by which of the following?

1) A complex of myosin, troponin, ATP and Pi
2) A high energy complex of myosin, ADP and Pi
3) A myosin ATP complex
4) Dissociated from the thick filaments
5) Inhibited by tropomyosin

A

5

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6
Q

Cilia are more likely to be found in which one of the following types of epithelium?

1) Pseudo-stratisfied columnar
2) Simple cuboidal
3) Stratified columnar
4) Stratified cuboidal
5) Transitional

A

1

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7
Q

In which type of joint does a slightly flexible interosseous ligament bind the bones?

1) Gomphosis
2) Suture
3) Symphesis
4) Synchondrosis
5) Syndesmosis

A

5

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8
Q

Which second messenger signals the release for Ca2+ from endoplasmic reticulum?

1) DAG
2) cAMP
3) cGMP
4) IP3
5) Nitric Oxide

A

4

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9
Q

Which one of the following correctly states a difference between skeletal muscle and smooth muscle contraction?

1) Skeletal - muscle contraction requires the influx of extracellular Ca2+ where as smooth muscle does not
2) Skeletal muscle contraction involves interactions between thick and thin filaments by smooth muscle does not
3) Skeletal muscle contraction results from cross-bridge cycling where as smooth muscle contraction does not
4) Skeletal muscle contraction requires release of Ca2+ from sarcoplasmic reticulum but smooth muscle doe snot
5) Skeletal muscle contraction is regulated by calcium acting on the thin filament but in smooth muscle it is the thick filament

A

5

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10
Q

All of the following drugs produce either direct or indirect parasympathomimetic effects except?

1) A beta-adrenoreceptor agonist
2) A direct muscarinic agonist
3) A direct nicotinic agonist
4) A muscarinic receptor agonist
5) A reversible cholinesterase inhibitor

A

A

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11
Q

Depolymerisation of microtubules is enhanced by which of the following?

1) Hydrolysis of ATP
2) Hydrolysis of GTP
3) Phosphorylation of alpha-tubulin subunits
4) Phosphorylation of GDP
5) Replacement of alpha-tubulin by beta-tubulin subunits

A

2

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12
Q

Which one of the following enzymes produced free glucose molecules during the breakdown of glycogen?

1) Debranching enxyme
2) Glucokinase
3) Glucose - 6 - phosphatase
4) Glycogen phosphorylase
5) Phosphorylase kinase

A

3

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13
Q

Nerve fibres of the sympathetic division of the autonomic nervous system originate in which of the following regions?

1) Brainstem and sacral
2) Cervical and thoracic
3) Cervical, thoracic and lumbar
4) Lumbar and sacral
5) Thoracic and lumbar

A

5

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14
Q

Which of the following passes through the diaphragm along with the oesophagus?

1) Azygos vein
2) Phrenic nerve
3) Right vagus
4) Sympathetic trunks
5) Thoracic ducts

A

3

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15
Q

The apex of the lungs is covered by which pleura?

1) Bronchopulmonary
2) Cervical
3) Costal
4) Diaphragmatic
5) Mediastinal

A

2

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16
Q

Which of the following refers to regions of the poorly perfused alveoli?

1) Alveolar dead space
2) Anatomical dead space
3) Bronchial dead space
4) Physiological dead space
5) Vascular dead space

A

1

Anatomical dead pace includes the nose and the pharynx

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17
Q

Which one of the following is the epithelium that lines the trachea?

1) Pseduostratified
2) Simple squamous
3) Stratified columnar
4) Stratified cuboidal
5) Transitional

A

1

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18
Q

Which one of the following is responsible for the greatest proportion of carbon dioxide carried in the blood?

1) Bicarbonate in erythrocytes
2) Bicarbonate in plasma
3) Carboamino albumin
4) Carbamino haemoglobin
5) Dissolved in plasma

A

1

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19
Q

The roots of which of the following permanent teeth are usually completed by the age of 10?

1) Lower canine
2) Lower second molar
3) Lower second premolar
4) Upper canine
5) Upper central incisor

A

5

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20
Q

Which of the following best describes the diaphragm?

1) It is active in both inspiration and expiration
2) It receives its blood supply entirely from the lower intercostal and subcostal arteries
3) The aorta is transmitted through an opening in the left crus (structure which extends below the diaphragm)
4) The left dome may ascend to the 5th intercostal space
5) The phrenic nerve branches run medially on its thoracic surface

A

4

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21
Q

Asthma is worsened by which of the following class of drugs?

1) Beta adrenoreceptor agonists
2) Beta adrenoreceptor antagonists
3) Muscarinic recetor agonists
4) Muscarinic receptor antagonists
5) Steroids

A

2 - it blocks the affect of adrenaline

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22
Q

At what age should a child have all their deciduous teeth?

1) 6 months
2) 9 months
3) 12 months
4) 3 years
5) 7 years

A

4

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23
Q

It is very important to feed a baby very soon after birth because in the first few hours the enzyme phosphoenolpyruvate carboxylase is present in very low amounts and what does this compromise?

1) Gluconeogenesis
2) Glucose phosphorylation
3) Glycogenesis
4) Glycogenolysis
5) TCA cycle

A

1

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24
Q

The action of acetylcholine after binding to muscarinic receptors on the SA node is to?
1) open K+ channels, causing hyperpolarization and a decreased
rate of spontaneous depolarization
2 )close K+ channels, causing depolarization and and increased
rate of spontaneous depolarization
3) open Ca2+ channels, causing increased Ca2+ entry and a
stronger contraction
4) close Ca2+ channels, causing decreased Ca2+ entry and a
faster rate of spontaneous depolarization
5) open Na+ channels, causing depolarization and increased
Ca2+ entry and a stronger contraction

A

1

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25
Q

The phrenic nerves innervate which of the following?

1) diaphragm
2) diaphragm and parietal pleura
3) diaphragm, parietal pleura and pericardium
4) diaphragm, parietal pleura and intercostal muscles
5) diaphragm, parietal pleura, pericardium and intercostal muscles

A

3

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26
Q

Caffeine inhibits cAMP phosphodiesterase. If caffeine is added to cells, which one of the following enzymes is phosphorylated and inactivated in the liver?

1) Glucokinase
2) Glycogen phosphorylase
3) Glycogen synthase
4) Phosphorylase kinase
5) Protein kinase A

A

3

cAMP phosphodiestase breaks down cAMP so there will be high amounts. This means that that glycogen breakdown will be stimulated.

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27
Q

In an anaerobic system that is metabolising glucose, which of the following compounds will increase in concentration following the addition of fluoride?

1) 2-phosphoglycerate
2) Acetyl-CoA
3) Glucose
4) Phosphoenolpyruvate
5) Pyruvate

A

1

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28
Q

Summation increases muscle force by increasing which one of the following?

1) Increased availability of ATP
2) Increased calcium levels around the myofibrils
3) Increased diffusion of oxygen delivered to muscle
4) Increased number of motor units being stimulated
5) Increased rate of stimulation

A

5

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29
Q

Which one of the following cell types is described as follows?
These cells circulate in the blood for 1-3 days, and then migrate into body
tissues, where they transform into macrophages. They will phagocytose
dead cells and bacteria and are important in the inflammatory response.
These cells can also transform into osteoclasts.
1) Basophil
2) Eosinophil
3) Lympthocyte
4) Monocyte
5) Neutophil

A

4

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30
Q

Excitation-contraction coupling refers especially to the:

1) attachment of myosin cross bridges to the thin filaments
2) binding of acetylcholine to the motor end plate and the movement of the troponin-tropomyosin complex
3) calcium release and binding to troponin molecules
4) events at the neuromuscular junction where a motor fibre excites a muscle cells
5) propagation of action potentials from the neuromuscular junction to the T-tubules

A

4

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31
Q

All cardiac veins empty into the —-, which then empties into the —-.

1) coronary sinus, left atrium
2) coronary sinus, right atrium
3) coronary sinus, superior vena cava
4) great cardiac vein, right atrium
5) great cardiac vein, left atrium

A

2

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32
Q

Which one of the following cell types is described as follows?
These cells are born in the bone marrow, and migrate from the peripheral
blood system after a few hours, into loose connective tissue in the
respiratory and gastointestinal tracts. They phagocytose antigen-antibody
complexes. They also produce histaminase, and aryl suphatase B, two
enzymes that inactivate two inflammatory agents released by mast cells. A
high blood count of these cells may indicate an allergic reaction
1) Basophil
2) Eosinophil
3) Lymphocyte
4) Monocyte
5) Neutrophil

A

2

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33
Q 
The pleural space into which lung tissue just above the
cardiac notch would tend to expand during deep inspiration is
the:
1) Anterior mediastinum
2) Costodiaphagmatic recess
3) Costomediastinal recess
4) Cupola 
5) Pulmonary ligament
A

3

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34
Q

During the cardiac cycle, the mitral valve opens at the end of:

1) Isovolumetric contraction
2) Isovolumetric relaxation
3) Rapid ejection
4) Rapid ventricular filling
5) Reduced ejection

A

2

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35
Q

Which one the following about motor proteins is incorrect?

1) Kinesin moves along the microtubule in the plus direction, whereas dynein moves in the minus direction
2) Motor proteins are the driving force behind movements generated by cilia and flagella
3) Myosin interactions with microfilaments are responsible for cell migration
4) The rate of movement of kinesin and dynein along the microtubule is determines primarily by the ATPase domain of the proteins
5) They stabilise the structure of microtubules

A

5

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36
Q

Which of the following is not relevant to secondary structure of proteins?

1) allowed phi and psi angles
2) amino acid sequence
3) covalent disulphide bonds
4) electrostatic interactions
5) hydrogen bonding

A

3

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37
Q

Which one of these amino acids is least compatible with an alpha helical structure?

1) Alanine
2) Histidine
3) Proline
4) Tryptophan
5) Tyrosine

A

3

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38
Q

Identify a pair of amino acids from the list that when incorporated into a protein, can participate in a hydrophilic interactions of basic side chains

1) Arginine and lysine
2) Asparagine and serine
3) Aspartic acid and lysine
4) Leucine and isoleucine
5) Phenylalanine and tryptophan

A

1

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39
Q

Which one of the following statements best describes when membrane fluidity is increased?

1) high proportion of trans unsaturated fatty acids
2) low proportion of cis unsaturated fatty acids
3) high proportion of cis unsaturated fatty acids
4) high proportion of saturated fatty acids
5) high proportion of cholesterol

A

3

trans unsaturated fatty acid tails tend to be straighter than cis tails

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40
Q

Which of the following best describes guanine nucelotide binding proteins? (G proteins)

1) are activated by phosphorylation of GDP to GTP
2) are active when GTP is bound to the receptor
3) are pentameric proteins
4) are 7 transmembrane spanning proteins
5) are switched off by hydrolysis of GTP to GDP

A

5

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41
Q

Which one of the following best describes tight junctions?

1) Always seen apical to adherens junctions
2) Always seen below adherens junctions
3) Can also form mucula adherens
4) Characterised by presence of keratin filaments
5) The most permeable type of cell junction

A

1

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42
Q

Which one of the following best desribes a cmponetn fo the skin that is composed of loose connective tissue?

1) Epidermis
2) Hypodermis
3) Reticular layer of dermis
4) Both 1 and 2
5) both 2 and 3

A

2

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43
Q

Which one is the most abundant sensory receptor in the skin?

1) Free nerve endings
2) Krause’s end bulbs
3) Meissner’s corpuscle
4) Pacinian corpuscle
5) Ruffini’s corpuscles

A

1

44
Q

Microvilli are most likely found in —- epithelium

1) Simple columnar
2) Simple cuboidal
3) Simple squamous
4) Stratified columnar
5) Transitional

A

1

45
Q

The tubercle of the 7th rib articulates with which one of the following structures?

1) Body of vertebra T6
2) Body of vertebra T7
3) Body of vertebra T8
4) Transverse process of vertebra T6
5) Transverse process of vertebra T7

A

5

46
Q

Which one of the following is a structure which passes through the superior and inferior thoracic aperture?

1) Abdominal aorta
2) Phrenic nerve
3) Oesophagus
4) Trachea
5) Vagus nerve

A

3

47
Q

Which of the following is not a type of glial cell found in the CNS?

1) Astrocyte
2) Ependymal cell
3) Microglia
4) Oligodendrocyte
5) Schwann cell

A

5

48
Q

Which leukocytes are present in the lowest concentraio in a blood smear of a healthy individual?

1) Basophil
2) Eosinohil
3) Lymphocyte
4) Monocyte
5) Neutrophil

A

1

49
Q

A male patient undergoing a procedure has a family history of malignant hyperthermia, respiratory acidosis when subjected to an inhaled general anaesthetic. Which one of these processes is most likely to be affected?

1) Inactivation of the ADP/ATP transporter
2) Increased activity of the ATP synthase
3) Inhibition of Complex 1
4) Inhibition of Complex 2
5) Uncoupling of oxidative phosphorylation

A

5

50
Q

The maximum pressure rise in the ventricle occurs during which one of the following?

1) Atrial systole
2) Diastole
3) Isovolumetric contraction
4) Rapid ejection
5) Ventricular filling

A

3

51
Q

Why is the adrenal gland unique in its autonomic innervation?

1) It is directly innervated by the spinal cord without passing through ganglia
2) It is innervated by parasympathetic cholinergic preganglionic neurons
3) It is innervated by preganglionic fibres originating inthe thoracic spinal cord from T2-T7
4) The postganglionic neurons are cholinergic rather than noradrenergic despite being part of the sympathetic nervous system
5) The post-synaptic response is mediated via muscarinic acetylcholine receptors

A

1

52
Q

Which of the following best describes the isovolumetric phase of the cardiac cycle?

1) atria contract and pump blood to ventricles
2) both atria and ventricles are relaxed
3) ventricles are relaxed and valves open to allow ventricular filling
4) ventricles contract and pump blood into the blood vessels
5) ventricles contract but ventricular pressure is lower then arterial pressure

A

2

53
Q

During cardiac cycle, the aortic value opens at the start of which one of the following?

1) isovolumetic contraction
2) isovolumetric relaxation
3) rapid ejection
4) rapid ventricular filling
5) reduced ejection

A

3

54
Q

Which one of these cells secretes histamine?

1) Basophil
2) Eosinophil
3) Lymphocyte
4) Monocyte
5) Neutrophil

A

1

55
Q

Which one of the following statements about the oxidative decarboxylation of pyruvate is correct?

1) forms acetyl-CoA which is fed into the citric acid cycle
2) forms oxaloacetate which is a substrate for glucoconeogenesis
3) is catalysed by the enzyme pyruvate decarboxylase
4) is reversible since there is a large decrease of free energy in the reaction
5) occurs in the cytosol

A

1

56
Q

Which of the following describes the action of acetylcholine after binding to muscarinic receptors on the SA node?

1) close K+ channels, causing depolarisation and increased rate of spontaneous depolarisation
2) open Ca2+ channels causing their entry and a stronger contraction
3) close Ca2+ channels, causing a decreased Ca2+ entry and a faster rate of spontaneous depolarisation
4) open K+ channels, causing hyperpolarisation and a decreased rate of spontaneous depolarisation
5) open Na+ channels, causing depolarisation and increased Ca2+ entry and a stronger contraction

A

4

57
Q

Which of the following best describes the properties of an allosteric inhibitor of an enzyme catalysed?

1) Binds to the active site
2) Participates in negative feedback regulation
3) Denatures the enzymes
4) Causes the enzyme to work faster
5) Is a hydrophobic compound

A

2

58
Q

The dicrotic notch in the cardiac cycle indicates which one of the following?

1) Aortic blood pressure is at a maximum
2) Mitral valve closing by contraction of the papillary muscles
3) Rebound of the aortic valve
4) The end of rapid ejection
5) The start of systole

A

3

59
Q

Isotonic contraction of a skeletal muscle if not associated with a change in which of the following?

1) Sarcomere length
2) Distance between A bands
3) Distance between I bands
4) Distance between Z lines
5) Distance between M lines

A

2

60
Q

The purkinje fibres are found in which layer of the heart?

1) Endocardium
2) Epicardium
3) Fibrous pericardium
4) Myocardium
5) Visceral pericardium

A

Myocardium

61
Q

Which one of the following substates in the TCA cycle is not coupled to the production of NADH or FADH2?

1) Alpha - ketoglutarate
2) Fumerate
3) Isocitrate
4) Malate
5) Succinate

A

2

62
Q

Which one of the following can be produced by a EPSP?

1) decreased excitability of a neuron
2) increased permeability of a postsynaptic to K+ and Cl- ions
3) Local depolarisation
4) Local hyperpolarisation
5) None of the above

A

3

63
Q

A drug which blocks beta adrenoreceptors is likely to cause which of the following?

1) A decrease in the force of myocardial contraction in someone with heart failure
2) A decreased dilatation by the blood vessels of skeletal muscles in response to circulating adrenaline
3) An increase in renin secretion
4) Dilation of the bronchi
5) Relaxation of sphincters in the alimentary tract

A

1

64
Q

Parasympathetic effects can be stimulated by which one of the following?

1) Alpha metyldopa (aldomet) which is first converted to alpha - methylnorepinephrine
2) Atropine which exerts similar effects as muscarine
3) Ephedrine which stimulate synthesis of acetylcholine
4) Large dose of nicotine which have effects similar to acetylcholine
5) Physotigime which inhibits acetylcholinesterase

A

5

65
Q

Which of the following compounds is an allosteric activator of phosphorylase b in muscle?

1) AMP
2) ATP
3) Glucose
4) Glucose 6 Phosphate
5) GTP

A

1

66
Q

Tricyclic antidepressants may produce blurred vision, dry mouth, constipation and difficulty initiating urination because of blockage of which . of the following?

1) Alpha - adrenergic receptors
2) GABA receptors
3) Muscarinic receptors
4) Nicotinic receptors
5) Serotonergic receptors

A

3

67
Q

A baby is born with congenital lactic acidosis because she has a defective electron transport protein. This causes a decrease in the rate at which NADH and FADH can be oxidised to produce ATP using oxidative phosphorylation.
Which of these would you not expect?
1) The concentration of ADP in the cell would increase and activate glycolysis
2) Increased glycolysis producing NADH and pyruvate
3) The inhibition of the electron transport chain would increase the concentration of NADH
4) The increase in NADH would increase the conversion of pyruvate to acetyl CoA
5) Increased NADH and pyruvate would be converted to lactate by lactate dehydrogenase

A

4

68
Q

Concerning allosteric effectors, which one of the following is correct?

1) ATP is a positive regulator of phosphofructokinase
2) Fructose 1,6, bis-phosphate is a negative regulator of pyruvate kinase
3) AMP is a negative regulator of phosphofructokinase
4) Phosphoenolpyruvate is a positive regulator of pyruvate kinase
5) ATP is a negative regulator of pyruvate kinase

A

4

69
Q

Which of the following best desribes the peptide bond in proteins?

1) Non-polar but rotates to three preferred dihedral angles
2) Non-polar and fixed in a trans comformation
3) Not cleavable by hydrolysis
4) Planar and usually found in a trans conformation
5) Planar but rotates to three preferred dihedral angles

A

4

70
Q

Hydrogen bonds in alpha-helices are….?

1) about 5Å in length
2) analogous to the steps in a spiral staircase
3) more numerous than Van der Waals interactions
4) not present at Phe residues
5) roughly parallel to the alpha helix

A

5

71
Q

Identify a pair of amino acids which where incorporated in a protein can contribute to hydrophobic interactions?

1) asparagine and serine
2) aspartic acid and lysine
3) cysteine and tyrosine
4) leucine and isoleucine
5) phenylalanine and tryptophan

A

4

72
Q

Polyprotic acids such as H3P04, can act as acid-base buffers only in combination with polyprotic bases in which one of the fowling conditions?

1) At equvalence points
2) At pH values around any of their pKa’s
3) At pH values around neutrality
4) At pH values halfway between their pKa’s
5) Only at low concentrations

A

2

73
Q

The pKa of glutamic acid is around 4 in an aqueous environment. When glutamic acid is located in the non-polar interior of the protein, tis apparent pKa —- and it becomes a —- acid.

1) remains the same, stronger
2) decreases, stronger
3) decreases, weaker
4) increases, stronger
5) increases, weaker

A

5

74
Q

Which one of the statements concerning microtubules and actin filaments is incorrect?

1) Both are necessary for cell division
2) Both are composed of globular subunits
3) Motor proteins participate in movements associated with both filaments
4) Both types of filaments display dynamic instability
5) Both filaments originate from a centrosome

A

5

75
Q 
Pharmcaokinetics is the effect of ---- and pharamcodynamics is the effect of ----
1) body on the drug; drug on the body
2) body on the drug; drug on a drug
3) drug on the body;
body on the drug
4) drug on a drug; body on the drug
5) drug on a drug; drug on a drug
A

1

76
Q

Which one of the following best describes the perichondrium?

1) contains blood vessels and nerves
2) contains manly loose connective tissue
3) covers the surface of articular cartilage
4) is important for the storage of fat
5) surrounds each lucuna in the matrix

A

1

77
Q

A major difference between bone tissue and other connective tissues lies in which one of the following.

1) the presence of collagen fibres in bone
2) the composition of the intracellular of bone
3) the presence of elastic fibres in bone
4) the limited blood supply available to bone tissue
5) the inability of bone cells to metabolise nutrients for energy

A

2

78
Q

Which one of the following best describes appositional growth of cartilage?

1) Chondrocytes in the centre of the cartilage lay down new matrix
2) Fribroblasts produce new chondrocytes
3) Chondroblasts in the perichondrium lay down new matrix
4) New osteons are formed from osteoblasts
5) Canaliculi connect between chondrocytes to allows transport of nutrients

A

3

79
Q

During the cardiac cycle, the aortic value closes at the end of …?

1) Isovolumetric contraction
2) Isovolumetric relaxation
3) Rapid ejection
4) ) Rapid ventricular filling
5) Reduced ejection

A

5

80
Q

On a diagram of the cardiac cycle, the sound S1 occurs when:

1) Opening of AV valves and rapid refilling
2) Atrial systole
3) Initiation of ventricular systole
4) Closure of semilunar valves
5) Opening of mitral valve

A

2

81
Q

A drug which blocks beta adrenoreceptors is likely to cause which one of the following?

1) A decrease in the force of myocardial contraction in someone with heart failure
2) A decreased dilation by the blood vessels of skeletal muscles in response to circulating adrenaline
3) An increase in renin secretion
4) Dilatation of the bronchi
5) Relaxation of sphincters in the alimentary tract

A

1

Beta adrenoreceptors have their biggest affect on cardiac muscle

82
Q

What is the name by which the action potential stimulates skeletal muscle to contract?

1) Endplate-contraction generation
2) Endplate potential generation
3) Excitation-contraction coupling
4) Inhibition-contraction coupling
5) Pacemaker potential coupling

A

3

83
Q

Which one of the following best describes a property of beta-pleated sheet structures?

1) Neighbouring chains are connected by alpha-helices
2) Neighbouring chains are hydrogen bonded
3) Neighbouring chains lie in a flat plane
4) Neighbouring residues are hydrogen bonded
5) Neighbouring residues have phi and psi angles of 90 degrees

A

2

84
Q

Which one of the following best describes a basic amino acid present in its hydroxylated form in collagen?

1) Arginine
2) Glysine
3) Leucine
4) Lysine
5) Phenylananine

A

4

85
Q

Which one of the following amino acid pairs have R groups that have a net positive charge at pH 7?

1) Arginine and lysine
2) Asparagine and aspartic acid
3) Glutamic acid and aspartic acid
4) Histidine and tyrosine
5) Isoleucine and serine

A

1

86
Q

The PL of an amino acid that has 3 ionsiable groups: NH2 (pka 10), COOH (pka 2.1) and side group with positive change (pka 6) is what?

1) 2
2) 4
3) 6
4) 8
5) 10

A

4

At pH 8, COOH and the side group will have lost a proton forming one negative and one no charge group. The NH2 group has a negative charge so this is the isoelectric point.

87
Q

Which of the following best describes the tissue which lines most ducts?

1) Simple squamous epithelium
2) Simple cuboidal epithelium
3) Simple columnar epithelium
4) Stratified squamous epithelium
5) Transitional epithelium

A

2

88
Q

Ligases catalyse:

1) the transfer of hydrogen atom and electrons
2) the transfer of functional groups from donors to acceptors
3) the cleavage of C-C, C-0 or C-N bonds
4) the cleavage of bonds by the addition of water
5) the transfer of functional groups within the same molecule
6) the formation of new covalent bonds
7) the addition of a phosphate group from an inorganic phosphate to an acceptor
8) removes a phosphate group from its substrate by hydrolysis
9) transfers a phosphate group from a nucleotide triphosphate (e.g. ATP)

A

6

89
Q

The product of glycolysis is:

1) 0 ATP 1 NADH
2) -1 ATP 1 NADH
3) -2 ATP -2 NADH
4) 2 ATP 1 NADH
5) 2 ATP 2 NADH

A

5

90
Q

A young relative of yours has never had too much energy. Tests reveal his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation for his condition?

1) His cells contain something that inhibits oxygen use in his mitochondria
2) His cells cannot move NADH from glycolysis into the mitochondria
3) His cells lack the enzyme in glycolysis that forms pyruvate
4) His mitochondria lack the transport protein that move pyruvate across the outer mitochondrial membrane
5) His cells have a defective electron transport chain, so glucose goes to lactate instead of acetyl CoA

A

4

91
Q

Muscle cells that are cylindrical and branched, each with a single, centrally located nucleus and that contract spontaneously are:

1) cardiac muscle
2) skeletal muscle
3) smooth muscle
4) both cardiac and skeletal muscle
5) not enough information to determine type

A

1

92
Q

In order for a skeletal muscle to contract, calcium ions must bind to:

1) Actin
2) Troponin
3) Tropomyosin
4) Myosin
5) Troponin and Tropomyosin

A

2

93
Q

Excitation-contraction coupling refers especially to the:

1) events at the neuromuscular junction where a motor fibre excites a muscle cell
2) propagation of action potentials from the neuromuscular junction to the T tubules
3) calcium release and binding to troponin molecules
4) attachment of myosin cross bridges to the thin filaments
5) opening of voltage gated calcium ion channels in the sarcoplasmic reticulum

A

1

94
Q

On a cardiac cycle, the sound S1 occurs when?

1) Opening of AV valves and rapid refilling
2) Atrial systole
3) Initiation of ventricular systole
4) Closure of semilunar valves
5) Opening of mitral valve

A

3

95
Q

The cardiac pacemaker potential is caused by cyclic changes in membrane potential that occur in which of the following sequences?

1) Slow inflow of Na+, rapid K+ inflow, slow K+ outflow
2) Slow inflow of Ca2+, rapid Na+ inflow, rapid K+ outflow
3) Slow inflow of K+ without Na+ inflow, rapid K+ outflow
4) Slow inflow of Na+ without K+ outflow, rapid Ca2+ inflow, rapid K+ outflow
5) Rapid Na+ inflow, rapid k+ outflow, slow inflow of Ca2+

A

4

96
Q

Which of the following best describes the regulation of glycolysis?

1) the pathway is switched off in the absence of oxygen
2) hexokinase is inhibited by its product gluocose-6-phosphate
3) ADP is an allosteric inhibitor of phoshofructokinase
4) citrate inhibits the enzyme pyruvate kinase
5) the reaction catalysed by aldolase is the rate limiting step

A

2

97
Q

The rate-limiting step in fatty acid synthesis is:

1) condensation of acetyl-coA and malonyl-CoA
2) formation of malonyl-CoA from malonate and coenzyme A
3) formation of acetyl-CoA from acetate
4) the reaction catalysed by acetyl-CoA carboxylase
5) the reduction of the acetoacetyl group to a beta-hydoxbutyryl group

A

4

98
Q

Comparing the effect of an inhibitor with an uncouple of oxidative phosphorylation:

1) the uncoupler would stop the oxidation of NADH by the electron transport chain
2) the inhibitor would allow electrons to pass through the electron transport chain
3) the uncoupler would inhibit the reduction of oxygen by the electron transport chain
4) the inhibitor would increase the pumping of protons by the electron transport chain
5) the uncoupler would increase hear production by the mitochondria

A

5

99
Q

Regarding the sympathetic division of the autonomic
nervous system:
1) acetylcholine is secreted by some sympathetic
postganglionic fibers
2) most sympathetic preganglionic fibres secrete
norepinephrine (noradrenaline).
3) sympathetic postganglionic neurons are found in spinal
segments from T1 to L5.
4) the sympathetic chain is restricted to the cranial nerves
5) sympathetic postganglionic fibres are located close to or
embedded within the organs they innervate

A

1

100
Q

Which one of the following best describes the effect of
tubocurarine (curare) on the neuromuscular junction?
1) Competes with ACh for receptor binding causing
depolarisation
2) Competes with ACh for receptor binding and but not result
in opening associated ion channel
3) Blocks voltage‐dependent Na+ conductance decreasing
depolarisation
4) Decreases K+ conductance and increases depolarisation
5) Decreases Ca2+ permeability producing hyerpolarisation

A

2

101
Q

Calcium is needed for contraction in both skeletal muscle and cardiac
muscle. However there are some differences in where it comes from and
what it does. Which one of these choices correctly describes how calcium
works in cardiac muscle cells?
1) Extracellular Ca2+ diffuses into the cardiac muscle cells, binds
to Ca2+ channels in the sarcoplasmic reticulum and causes
Ca2+ release into the cytosol
2) Extracellular Ca2+ diffuses into the cardiac muscle cells, binds
to troponin and initiates contraction.
3) Ca2+ from the sarcoplasmic reticulum diffuses out of the cell,
causing the plateau phase of the action potential.
4) Ca2+ from the sarcoplasmic reticulum diffuses out of the cell,
causing repolarisation.

A

1

102
Q

Which one of the following statements concerning
cardiac muscle is correct?
1) Cardiac muscle has a well‐developed system of T tubules
2) Heart rate is decreased by stimulation of the cardiac
sympathetic nerves
3) The action potential of cardiac muscle fibres is initiated by
action potentials in sympathetic nerve fibres
4) The force of contraction is not regulated by G proteins
5) The myocytes of the SA node generate spontaneous action
potentials that set the heart rate

A

5

103
Q

In which choice are the components of the cardiac
conduction system listed in the correct sequence?
1) AV node, SA node, Purkinje fibres, AV bundle
2) AV node, AV bundle, SA node, Purkinje fibres
3) SA node, AV bundle, AV node, Purkinje fibres
4) SA node, AV node, AV bundle, Purkinje fibres
5) SA node, Purkinje fibres, AV node, AV bundle

A

4

104
Q

The Frank-Starling law of the heart says that a higher end diastolic volume is related by which of the following?

1) decreased sympathetic activity
2) decreased blood pressure
3) decreased cardiac output
4) increased end systolic volume
5) increased stroke volume

A

5

105
Q

Of the 20 standard amino acids, only — is not optically active. The reason for this is that it has a side chain of —-?

1) proline - forms a covalent bond with the amino group
2) alanine - a simple methyl group
3) glycine - a hydrogen atom
4) alanine - contains only hydrogen
5) glycine - is unbranched

A

3

106
Q

A blockage of which one of this would cause a decrease in blood pressure?
1) muscarinic receptors in the CNS
2) muscarinic receptors in the periphery
3) nicotinic receptors in autonomic ganglia
4) nicotinic receptors on chromaffin cells
5) nicotinic receptors at the neuromuscular
junction (NM)

A

3

Dentistry Exam Questions (3 decks)

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