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Question 1
Incorrect
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Which of the following features do mast cells and basophils have in common:
Your Answer: Small proportion enter the tissues in healthy individuals
Correct Answer: Are essential for immediate type-hypersensitivity reactions
Explanation:Anaphylaxis is a severe immediate allergic reaction of rapid onset affecting many body systems. It is due to the release of inflammatory mediators and cytokines from mast cells and basophils. Basophils are the least common of the granulocytes, representing about 0.5 to 1% of circulating white blood cells. However, they are the largest type of granulocyte. They are responsible for inflammatory reactions during immune response, as well as in the formation of acute and chronic allergic diseases, including anaphylaxis, asthma, atopic dermatitis and hay fever. They can perform phagocytosis (cell eating), produce histamine and serotonin that induce inflammation, and heparin that prevents blood clotting. Mast cells are similar in appearance and function. Both cell types store histamine, a chemical that is secreted by the cells when stimulated.
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This question is part of the following fields:
- Immunology
- Physiology
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Question 2
Incorrect
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Which of the following factors is directly responsible for the breakdown of fibrinogen to fibrin?
Your Answer: Plasmin
Correct Answer: Thrombin
Explanation:Prothrombin (coagulation factor II) is proteolytically cleaved to form thrombin in the coagulation cascade, the clotting process. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalysing many other coagulation-related reactions.
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This question is part of the following fields:
- Haematology
- Physiology
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Question 3
Incorrect
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What is the reason for a deranged thrombin clotting time?
Your Answer: Warfarin therapy
Correct Answer: Heparin therapy
Explanation:Thrombic clotting time is also known as thrombin time. It is clinically performed to determine the therapeutic levels of heparin. After plasma is isolated from the blood, bovine thrombin is added to it and the time it takes from the addition to clot is recorded. The reference interval is usually <21s. deranged results are indicative of heparin therapy, hypofibrinogenemia, hyperfibrinogenaemia or lupus anticoagulant.
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This question is part of the following fields:
- Haematology
- Physiology
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Question 4
Incorrect
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Which statement is correct about the clinical state of methemoglobinemia?
Your Answer: It is due to carbon monoxide reacting with haemoglobin.
Correct Answer: May arise due to a hereditary deficiency of NADH.
Explanation:Methaemoglobin is a form of haemoglobin that contains ferric [Fe3+] iron and has a decreased ability to bind oxygen. Spontaneously formed methaemoglobin is normally reduced by protective enzyme systems, e.g., NADH methaemoglobin reductase, hence a deficiency of NADH may result in increased levels of methaemoglobin
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This question is part of the following fields:
- Haematology
- Physiology
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Question 5
Incorrect
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Southern Blotting and DNA probes
Your Answer: Gene probes can consist of DNA or RNA
Correct Answer: RNA fragments are separated by gel electrophoresis and transferred onto membrane sheets in southern blotting
Explanation:Restriction enzymes always cut at different positions. There are different restriction endonucleases for different nucleotide sequences.
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This question is part of the following fields:
- Genetics
- Physiology
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Question 6
Correct
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A 23-year-old student presents with a fever and sore throat. Upon physical examination, it was observed that he had bilaterally enlarged tonsils that are covered in large amounts of exudate. A diagnosis of tonsillitis was made. The lymph from the tonsils will drain to which of the following nodes?
Your Answer: Deep cervical lymph nodes
Explanation:The tonsils are collections of lymphatic tissue located within the pharynx. They collectively form a ringed arrangement, known as Waldeyer’s ring: pharyngeal tonsil, 2 tubal tonsils, 2 palatine tonsils, and the lingual tonsil. Lymphatic fluid from the lingual tonsil drains into the jugulodigastric and deep cervical lymph nodes. Lymphatic fluid from the pharyngeal tonsil drains into the retropharyngeal nodes (which empty into the deep cervical chain), and directly into deep cervical nodes within the parapharyngeal space. The retropharyngeal and the deep cervical lymph nodes drain the tubal tonsils. The palatine tonsils drain to the jugulodigastric node, a node of the deep cervical lymph nodes, located inferior to the angle of the mandible.
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 7
Incorrect
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Regarding cardiac contractility, catecholamines exert their inotropic effect via:
Your Answer: Myocardial Na+/K+ ATPase
Correct Answer: Î’1-adrenergic receptors and gs
Explanation:Catecholamines exert their inotropic effect on the heart via the B1 adrenergic receptors and Gs, stimulating adenyl cyclase and increasing the production of cAMP.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 8
Incorrect
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In RFLP, the DNA fragments are separated by length through a process known as:
Your Answer: Deletion
Correct Answer: Inversion
Explanation:Samples of DNA from individuals are broken into pieces by restriction enzymes and the fragments are separated according to their lengths via gel electrophoresis. Although now largely obsolete due to the rise of inexpensive DNA sequencing technologies, RFLP analysis was the first DNA profiling technique inexpensive enough to see widespread application.
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This question is part of the following fields:
- Genetics
- Physiology
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Question 9
Correct
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Myocardial contractility is improved by:
Your Answer: Caffeine
Explanation:Caffeine and other theophyllines breakdown cAMP and have a positive ionotropic effect on the heart. Drugs like quinidine, procainamide and conditions like hypoxia and hypercapnia decreases the contractility of the heart.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 10
Incorrect
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During a surgical operation, whilst dissecting the mediastinal lymph nodes for a bronchogenic carcinoma of the right upper lobe bronchus, a patient's right sympathetic trunk is accidentally severed above the level of spinal nerve T1. Which function would be left intact in the affected region?
Your Answer: Sweat production
Correct Answer: Voluntary muscle activity
Explanation:The sympathetic nervous system regulates vascular tone, dilation of pupils, arrector pili muscles, sweat production and visceral reflexes. Neurones that supply the voluntary muscles originate from the ventral horn of the spinal cord. If these nerves were thus damaged, these functions would be impaired. The sympathetic nervous system is not responsible for voluntary muscle activity.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 11
Incorrect
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Afferent A δ fibers from nociceptors terminate primarily on neurons in which lamina:
Your Answer: II and V
Correct Answer: I and V
Explanation:Nociceptors are receptors of pain sensation. There are 2 primary afferent/sensory pain fibers which transmit impulses from the receptor to the CNS, specifically to the dorsal horn of the spinal cord. The two fibers are A δ and C fibers. The dorsal horn of the spinal cord is the relay centre for sensory information converging from the periphery. Grey matter of the dorsal horn is subdivided in to laminae based on cytoarchitecture. C fibers terminate in lamina II the substantia gelatinosa. A δ fibers terminate primarily in lamina I but some project more deeply to terminate in lamina V.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 12
Incorrect
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Which is true of the citric acid cycle?
Your Answer: Acetyl-CoA is the only entry point
Correct Answer: Involves a series of reactions where oxaloacetate is regenerated
Explanation:The cycle consumes acetate (in the form of acetyl-CoA) and water, reduces NAD+ to NADH, and produces carbon dioxide as a waste by-product. The NADH generated by the citric acid cycle is fed into the oxidative phosphorylation (electron transport) pathway. At the end of each cycle, the four-carbon oxaloacetate has been regenerated, and the cycle continues. The net result of these two closely linked pathways is the oxidation of nutrients to produce usable chemical energy in the form of ATP. Acetyl-CoA, is the starting point for the citric acid cycle and in eukaryotic cells, the citric acid cycle occurs in the matrix of the mitochondrion. Though the Krebs cycle does not directly require oxygen, it can only take place when oxygen is present because it relies on by-products and is therefore an aerobic process.
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This question is part of the following fields:
- Cell Biology
- Physiology
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Question 13
Incorrect
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Which of the following statements is correct regarding flow through the cardiovascular system?
Your Answer: If the vessel diameter is suddenly reduced, flow rate will increase.
Correct Answer: Turbulent blood flow may be caused by increased cardiac output.
Explanation:Frictional forces at the sides of a vessel cause a drag force on the fluid touching them in laminar blood flow, which creates a velocity gradient where the flow is greatest at the centre. Laminar blood flow may become disrupted and flow may become turbulent at high velocities, especially in large arteries or where the velocity increases sharply at points of sudden narrowing in the vessels, or across valves. There is increased tendency for thrombi formation when there is turbulent blood flow. Clinically, turbulence may be heard as a murmur or a bruit. As a result of elevated cardiac output, there may be turbulent blood flow, even when the cardiac valves are anatomically normal, and as a result, a physiological murmur can be heard. One such example is pregnancy.
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This question is part of the following fields:
- Cell Biology
- Physiology
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Question 14
Incorrect
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Which of the following morphological features is most characteristic of hyaline degeneration?
Your Answer: Orphan Annie eye nucleus
Correct Answer: Homogeneous, ground-glass, pink-staining appearance of cells
Explanation:The characteristic morphological features of hyaline degeneration is ground-glass, pinking staining cytoplasm with an intact cell membrane. The accumulation of lipids, calcium salts, lipofuscin and an amorphous cytoplasm with an intact cell membrane are all characteristically found in different situations. Pyknotic nucleus and orphan Annie eye nucleus are not seen in hyaline degeneration.
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This question is part of the following fields:
- Cell Injury & Wound Healing
- Pathology
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Question 15
Correct
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What are the major motor proteins that interact with microtubules?
Your Answer: Kinesin and dynein
Explanation:The major motor proteins that interact with microtubules are kinesin, which usually moves toward the (+) end of the microtubule, and dynein, which moves toward the (−) end.
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This question is part of the following fields:
- Cell Biology
- Physiology
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Question 16
Correct
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Chief cells secrete:
Your Answer: Pepsinogen and gastric lipase
Explanation:A gastric chief cell (or peptic cell, or gastric zymogenic cell) is a type of cell in the stomach that releases pepsinogen and gastric lipase.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 17
Incorrect
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Which of the following regulates the calcium release channels?
Your Answer: Both a and d
Correct Answer: Calstabin 2
Explanation:Ca2+ is released from the SR through a Ca2+ release channel, a cardiac isoform of the ryanodine receptor (RyR2), which controls intracytoplasmic [Ca2+] and, as in vascular smooth-muscle cells, leads to the local changes in intracellular [Ca2+] called calcium sparks. A number of regulatory proteins, including calstabin 2, inhibit RyR2 and, thereby, the release of Ca2+ from the SR.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 18
Incorrect
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A 27-year-old female was admitted due to severe dehydration. The patient also complained of chest tightness, thus an ECG was requested. The ECG strip showed an isoelectric ST segment, upright T wave, with prominent U waves. What is the most likely electrolyte abnormality responsible for these ECG tracing?
Your Answer: Hypocalcaemia
Correct Answer: Hypokalaemia
Explanation:U waves are prominent if it is >1-2mm or 25% of the height of the T wave. Abnormally prominent U waves are characteristically seen in severe hypokalaemia.
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This question is part of the following fields:
- Fluids & Electrolytes
- Pathology
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Question 19
Incorrect
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Compact/cortical bone makes up
Your Answer: Inner layer of most bones and accounts for 80% of bone in the body
Correct Answer: The outer layer of most bones and accounts for 80% of bone in the body
Explanation:Cortical, lamellar, or compact bone, is more dense than spongy bone and it forms the rigid, outer layer of bones, also called cortex. It consists of packed osteons, with a central osteonic canal surrounded by concentric rings. Spaces called lacunae are filled with osteocytes, and channels called canaliculi go from the lacunae to the osteonic canal. The strength of cortical bone allows it to support the body and protect organs. It also stores different elements, such as calcium.
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This question is part of the following fields:
- Endocrinology
- Physiology
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Question 20
Incorrect
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Which one of the following ECG findings is least associated with digoxin use?
Your Answer: Flattened T waves
Correct Answer: Prolonged QT interval
Explanation:Digoxin ECG features:•   ST depression (‘reverse tick’)•   flattened/inverted T waves• Prolonged PR interval•   short QT interval•   arrhythmias e.g. AV block, bradycardia, ventricular tachycardia or fibrillation (for example paroxysmal atrial tachycardia with A-V block – so-called PAT with block) is said to be pathognomonic (i.e. diagnostic) of digoxin toxicity.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 21
Incorrect
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The primary sensory cortex is:
Your Answer: Brodmann area 4
Correct Answer: Brodmann area 3,1,2
Explanation:A Brodmann area in the brain is defined by cytoarchitecture, histology and organization of cells:Primary somatosensory cortex is areas 3,1, and 2Primary Motor 4Premotor 6Primary Visual 17Primary Auditory 41Brocas 44
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This question is part of the following fields:
- Neurology
- Physiology
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Question 22
Incorrect
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What is the result of maltase deficiency in the brush border of the small intestine?
Your Answer: Decreases rate of absorption of ingested glucose
Correct Answer: Results in increased passage of maltose in stool
Explanation:Maltase is an enzyme produced from the surface cells of the villi, lining the small intestine and aids in hydrolysing the disaccharide maltose, which splits into two molecules of α-glucose. It is done by breaking the glycosidic bond between the ‘first’ carbon of one glucose and the ‘fourth’ carbon of the other (a 1–4 bond). Hence, a deficiency of enzyme maltase will result in the increased passage of maltose in the stool.
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This question is part of the following fields:
- Gastrointestinal
- Physiology
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Question 23
Correct
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The outer muscular layer of the oesophagus is covered by?
Your Answer: Loose connective tissue
Explanation:The oesophagus has four layers namely; 1. the mucosal layer, 2. the submucosal layer, 3. the muscular layer and 4. the layer of loose connective tissue which binds to the outer mucosal layer. The oesophagus lacks the serosal layer and therefore holds sutures poorly. The mucosal layer consists of muscularis mucosa and the lamina propria and is made up of non keratinised stratified squamous epithelium. The mucosal layer is the innermost layer of the oesophagus. The submucosal layer being the strongest layer of all has mucous glands which are called as the tuboalveolar mucous glands. The outer muscular layer has two types of muscle layers of which one is the circular layer and the other the longitudinal layer. The Auerbach’s and Meissner’s nerve plexuses lie in between the longitudinal and circular muscle layers and submucosally. The muscle fibres present in the upper 1/3rd part of the oesophagus are skeletal muscle fibres, the middle 1/3rd layer has both smooth and skeletal muscle fibres, but the lower 1/3rd only has smooth muscle fibres. The loose connective tissue layer or the adventitious layer has dense fibrous tissue.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 24
Correct
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Myelin sheath in the CNS is produced by?
Your Answer: Oligodendrocytes
Explanation:CNS myelin is produced by special cells called oligodendrocytes. PNS myelin is produced by Schwann cells. The two types of myelin are chemically different, but they both perform the same function — to promote efficient transmission of a nerve impulse along the axon.
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This question is part of the following fields:
- Neurology
- Physiology
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Question 25
Incorrect
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With regard to the cell cycle. In which part of the cycle does DNA replication occur?
Your Answer: G0
Correct Answer: Interphase
Explanation:DNA replication occurs during S phase but that isn’t one of the options. Remember Interphase comprises G1,S and G2 phases!
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This question is part of the following fields:
- Cell Biology
- Physiology
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Question 26
Incorrect
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Which one of the following is a risk factor for torsade de pointes?
Your Answer: Hyperkalaemia
Correct Answer: Hypothermia
Explanation:The following is a list of factors associated with an increased tendency toward torsades de pointes:- Hypokalaemia (low blood potassium)- Hypomagnesemia (low blood magnesium)- Hypocalcaemia (low blood calcium)- Bradycardia (slow heartbeat)- Heart failure- Left ventricular hypertrophy- Hypothermia- Subarachnoid haemorrhage- Hypothyroidism
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 27
Incorrect
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A nuchal translucency measurement is taken from the nape of the foetus' neck to screen for Down's syndrome.Which of these is the embryological origin of this tissue?
Your Answer: Mesoderm
Correct Answer: Ectoderm
Explanation:The origins of the neural tube and the nape of the neck where nuchal translucency measurements are taken are from embryonic ectoderm.The structural development of the head and neck occurs between the third and eighth weeks of gestation. The 5 pairs of branchial arches, corresponding to the primitive vertebrae gill bars, that form on either side of the pharyngeal foregut on day 22 are the embryologic basis of all the differentiated structures of the head and neck. Each arch consists of 3 layers: an outer covering of ectoderm, an inner covering of endoderm, and a middle core of mesenchyme. These arches are separated further into external, ectoderm-lined pharyngeal clefts and internal, endoderm-lined pharyngeal pouchesA population of ectodermal cells adjacent to the neural fold and not included in the overlying surface (somatic) ectoderm gives rise to the formation of the neural crest. These neuroectodermal crest cells are believed to migrate widely throughout the developing embryo in a relatively cell-free enriched extracellular matrix and differentiate into a wide array of cell and tissue types, influenced by the local environment. Most connective and skeletal tissues of the cranium and face ultimately come from the derivatives of neural crest cells.
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This question is part of the following fields:
- Antomy
- Embryology
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Question 28
Correct
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Coagulative necrosis is typically seen in which of the following:
Your Answer: Myocardial infarction
Explanation:Coagulative necrosis is the most common form of necrosis characterised by the loss of cell nuclei, but with general preservation of the underlying architecture. Dead tissue is macroscopically pale and firm. This is the classic pattern seen in myocardial infarction.Liquefactive necrosis leads to complete loss of cellular structure and conversion into a soft, semi-solid mass. This is typically seen in the brain following cerebral infarction.Caseous necrosis is most commonly seen in tuberculosis. Histologically, the complete loss of normal tissue architecture is replaced by amorphous, granular and eosinophilic tissue with a variable amount of fat and an appearance reminiscent of cottage cheese.Gangrenous necrosis is necrosis with putrefaction of tissues due to exposure to air (dry gangrene) or infection (wet gangrene).
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This question is part of the following fields:
- Inflammatory Responses
- Pathology
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Question 29
Incorrect
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Which factors increase the end-diastolic volume?
Your Answer: Raised intra-pericardial pressure
Correct Answer: Constriction of veins
Explanation:End diastolic volume is also known as preload. It is the amount of blood the heart contracts against. Constriction of veins will decrease venous pooling and increase venous return, hence increasing the end diastolic volume. Standing will increase venous pooling hence decreasing venous return and end diastolic volume. Raised intrapericardial pressure will also decrease venous return and hence end diastolic volume.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 30
Incorrect
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Which of the following causes the closure of the ductus arteriosus during birth?
Your Answer: Increased levels of prostaglandins
Correct Answer: Reduced levels of prostaglandins
Explanation:Ductus arteriosus is kept open by the prostaglandin E2 which is a vasodilator. At birth the high levels of cyclooxygenase blocks the production of prostaglandins which results in the closure of the ductus arteriosus.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
