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Question 1
Correct
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Question 2
Incorrect
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How does the proximal convoluted tubule excrete H+?
Your Answer: Facilitated by a Na/K+ ATPase.
Correct Answer: Via Na+/H+ antiporter.
Explanation:H+ secretion from cells across the luminal membrane is mostly in exchange for Na+ ions, and to a small extent, through a proton ATPase. Secreted H+ react with filtered HC03- to form H2CO3.
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This question is part of the following fields:
- Medicine
- Renal
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Question 3
Correct
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Which one of the following have not been shown to improve mortality in patients with chronic heart failure?
Your Answer: Furosemide
Explanation:A number of drugs have been shown to improve mortality in patients with chronic heart failure:
- ACE inhibitors (SAVE, SOLVD, CONSENSUS)
- spironolactone (RALES)
- beta-blockers (CIBIS)
- hydralazine with nitrates (VHEFT-1)
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 4
Correct
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Which cells produce the immunoglobulin proteins involved in mediating humoral immunity?
Your Answer: Differentiated forms of B lymphocytes known as plasma cells
Explanation:After the B cells have been activated by a certain antigens, they transform into plasma cells. These plasma cells are responsible for the generation of antibodies (or immunoglobulins Ig) which are also known as regulators of humoral immunity. There are fives classes of Ig: IgA, IgG, IgM, IgE and IgD
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This question is part of the following fields:
- Immunology
- Medicine
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Question 5
Correct
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Which of the following are true when it comes to tumour suppressor genes:
Your Answer: All of the options are true
Explanation:All of the above mentioned statements are true regarding tumour suppressor genes. Tumour suppressor genes generally follow the two-hit hypothesis, which implies that both alleles that code for a particular protein must be affected before an effect is manifested.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 6
Correct
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Which one of the following skin disorders is least commonly associated with hypothyroidism?
Your Answer: Pretibial myxoedema
Explanation:Pretibial myxoedema is an infiltrative dermopathy, resulting as a rare complication of Graves’ disease (hyperthyroidism) and very occasionally occurs in non-thyrotoxic Graves’ disease and Hashimoto’s thyroiditis.
Hypothyroidism typically presents with symptoms such as dry skin, brittle hair, and thinning of the outer third of the eyebrows. While skin conditions like dryness and hair changes are common in hypothyroidism due to reduced metabolic activity, acne is also not typically associated with it.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 7
Incorrect
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Which of the following happens when anterograde neurons are stimulated?
Your Answer: Smooth muscle contraction ahead of the stimulus
Correct Answer: Smooth muscle relaxation ahead of the stimulus
Explanation:Nitric oxide is thought to act as an anterograde neurotransmitter. Nitric oxide causes relaxation of smooth muscles ahead of the stimulus. Clinically it is used as a potent vasodilator.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 8
Incorrect
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Which of the following proteins are NOT synthesized in the liver?
Your Answer: Y-globulin
Correct Answer: Steroid
Explanation:Human steroidogenesis occurs in a number of locations:- Corticosteroids are produced in the adrenal cortex.- Oestrogen and progesterone are made primarily in the ovary and the placenta during pregnancy, and testosterone in the testes.- Testosterone is also converted to oestrogen to regulate the supply of each in females and males.- Some neurons and glia in the central nervous system (CNS) express the enzymes required for the local synthesis of pregnant neurosteroids, de novo or from peripheral sources.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 9
Correct
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Which of the following occurs during a Valsalva manoeuvre?
Your Answer: An initial rise in blood pressure
Explanation:The Valsalva maneuver involves forced expiration against a closed glottis. It has several phases, each affecting the cardiovascular system differently:
- Phase I: During the initial forced expiration against the closed glottis, there is a transient rise in intrathoracic pressure, which compresses the thoracic aorta and causes a brief increase in blood pressure.
- Phase II: Continued straining leads to decreased venous return to the heart, reducing cardiac output and causing a drop in blood pressure. This phase is characterized by a compensatory increase in heart rate.
- Phase III: Upon releasing the strain, there is a sudden drop in intrathoracic pressure, which momentarily decreases blood pressure.
- Phase IV: Blood pressure then rises rapidly as venous return to the heart is restored, leading to increased cardiac output. This is often followed by a reflex bradycardia (slow heart rate).
Given these phases, the most accurate statement about what occurs during the Valsalva maneuver is the initial rise in blood pressure (Phase I).
Other options explained:
- Forced inspiration against a closed glottis: Incorrect. The Valsalva maneuver involves forced expiration, not inspiration, against a closed glottis.
- Low intrathoracic pressures throughout: Incorrect. The Valsalva maneuver involves high intrathoracic pressures due to forced expiration.
- Disruption of autonomic function: Incorrect. The Valsalva maneuver affects autonomic function but does not disrupt it. Instead, it triggers autonomic responses to changes in blood pressure and heart rate.
- No change: Incorrect. The Valsalva maneuver causes significant changes in blood pressure and heart rate.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Correct
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Select the correct statement regarding the macro anatomy of the thyroid gland.
Your Answer: It surrounds the trachea at the front of the neck.
Explanation:The thyroid is located around the trachea, in the anterior portion of the neck. It is formed by two lobes which are connected by an isthmus. The presence of a pyramidal lobe, or third lobe, is considered to be a normal anatomical variant. It originates from the primitive pharynx and the neural crest and has a rich vascular supply.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 11
Correct
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Relaxation of the cardiac muscle at the actin-myosin cross bridges is initiated by binding of which molecule to the exposed site on the myosin.
Your Answer: ATP
Explanation:A crossbridge is a myosin projection, consisting of two myosin heads, that extends from the thick filaments. Each myosin head has two binding sites: one for ATP and another for actin. The binding of ATP to a myosin head detaches myosin from actin, thereby allowing myosin to bind to another actin molecule. Once attached, the ATP is hydrolysed by myosin, which uses the released energy to move into the cocked position whereby it binds weakly to a part of the actin binding site.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 12
Correct
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The layers of the neocortex from the 1st to the 6th are arranged as follows:
Your Answer: Molecular, external granular, external pyramidal, internal granular, internal pyramidal, multiform
Explanation:The layers of neocortex from outermost to innermost include: the molecular, external granular layer, external pyramidal, internal granular, internal pyramidal and multiform layer.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 13
Correct
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A 23 year old male patient presents with urethritis for the last 2 weeks that has not responded to antibiotics. Lately he has developed an onset of new range of symptoms that are linked to his HLA B27 positivity. Which of the following signs is not related to Reiter's syndrome?
Your Answer: A mild fever with a generalised macular rash
Explanation:Reactive arthritis, (formerly known as Reiter’s syndrome), is an autoimmune condition that occurs after a bacterial infection of the gastrointestinal or urinary tract. It is categorized as a seronegative spondylarthritis because of its association with HLA-B27. Reactive arthritis primarily affects young men and usually presents with musculoskeletal or extra‑articular symptoms. The characteristic triad consists of arthritis, conjunctivitis, and urethritis. The diagnosis is based on clinical features such as patient history and physical examination; there are no specific tests for reactive arthritis. Treatment is primarily symptomatic and consists of the administration of NSAIDs, as most patients recover spontaneously. Dermatologic manifestations include skin lesions of the glans resembling psoriasis (balanitis circinata); hyperkeratinisation of the palms and soles (keratoderma blenorrhagicum)
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 14
Correct
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Where does the pituitary gland lie?
Your Answer: In a pocket of the sphenoid bone at the base of the brain
Explanation:The pituitary lies in a small depression in the sphenoid bone, known as the sella turcica or Turkish saddle.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 15
Correct
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During the gastric phase, the acid secretion process is stimulated in the G cells by?
Your Answer: Vagal stimulation, distention of the stomach wall, oligopeptides in the stomach
Explanation:Before the meal enters into the stomach, the amount of secretion is limited. Swallowing of a food bolus triggers the release of gastrin. Once in the stomach, the meal physically distends the stomach activating the stretch receptors and initiating the vago vagal reflex amplifying the secretion during the gastric phase.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 16
Correct
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What is the structure of nucleosomes?
Your Answer: Strands of double strand DNA + histones
Explanation:DNA is packed and condensed by binding to histone proteins. The double stranded DNA forms a complex with histone proteins which is called a nucleosome. There are 8 histone proteins contained in one core of nucleosome.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 17
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
- Medicine
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Question 18
Correct
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On a mountain the atmospheric pressure is 700 mmHg and the humidity close to zero, the partial pressure of oxygen is:
Your Answer: 147 mmHg
Explanation:Natural air includes approximately 21% of oxygen. If humidity is zero, the partial pressure of oxygen is 700 × 21% = 147 mmHg
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 19
Correct
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Calcium is mobilized from the sarcoplasmic reticulum through:
Your Answer: Ryanodine receptor (RyR2) calcium release channels
Explanation:During the plateau phase of the action potential, calcium from the extracellular fluid enters through the L type of calcium channels. This entry triggers the release of more calcium from the sarcoplasmic reticulum via the ryanodine receptors. As a result intracellular calcium increases binding to troponin C resulting in contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 20
Correct
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An 18 year old boy, thin with a tall stature, and a high arched palate arrives at the hospital with a spontaneous pneumothorax. He is accompanied by his brother who has a similar appearance. You suspect Marfan's Syndrome. The gene encoding which of the following proteins is defective in this condition?
Your Answer: Fibrillin-1
Explanation:A variety of proteins compose the structure of microfibrils, the most prominent of which are the two fibrillins. Fibrillin-1 a scaffolding protein is encoded by FBN1 on human chromosome 15q21 and fibrillin-2 is encoded by FBN2 on 5q23. Mutations in FBN1 produce Marfan syndrome, a pleiotropic autosomal dominant connective tissue disorder with prominent manifestations in the skeleton, eye and cardiovascular system. A number of conditions related to Marfan syndrome are also due to FBN1 mutations.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 21
Correct
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A 22 year old nulliparous female presents with shortness of breath. She has a history of recurrent deep vein thrombosis. Complete blood count and clotting screen reveals the following results:Hb: 12.4 g/dl Plt: 137 WBC: 7.5*109/l PT: 14 secs APTT: 46 secs Which of the following would be the most likely diagnosis?
Your Answer: Antiphospholipid syndrome
Explanation:The combination of APTT and low platelets with recurrent DVTs make antiphospholipid syndrome the most likely diagnosis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 22
Correct
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Which statement is incorrect regarding transcription of DNA?
Your Answer: A gene is always read in the 3’-5’ orientation and at 3’ promoter sites.
Explanation:In both prokaryotes and eukaryotes RNA polymerase acts in the 5′-3′ direction and hence the RNA is transcribed in this direction. The mRNA produced is immature as it has introns as well as exons presents. It undergoes a process known as splicing to remove the exons and then interacts with the ribosomes to form proteins.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 23
Correct
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Portal vein receives its blood from all the following except:
Your Answer: Kidney
Explanation:The portal vein receives blood from the intestines via the superior and inferior mesenteric veins, from stomach via the gastric veins and from the spleen and pancreas via splenic vein. The kidney is supplied by the renal artery and drains into the renal vein into the inferior venacava.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 24
Correct
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A 79-year-old woman has a waddling gait. History reveals enuresis and change in behaviour. What is the most likely diagnosis?
Your Answer: Normal pressure hydrocephalus
Explanation:The waddling gait and behaviour change are attributes of normal pressure hydrocephalus along with loss of bladder control which commonly happens with elder age.
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This question is part of the following fields:
- Geriatrics
- Medicine
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Question 25
Incorrect
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Near the transcription site of a gene, the site at which RNA polymerase and its cofactors bind is known as the:
Your Answer: Regulator
Correct Answer: Promotor
Explanation:Transcription will begin when the RNA polymerase II binds to the promotor. The promotor is a sequence of 25 nucleotides found upstream from the start site of transcription. This promotor sequence is known as the TATA box. Transcription factors also bond along with RNA polymerase to this site to form a complex. However some may bind to regulatory elements proximal to the promotor site.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 26
Correct
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Where is intrinsic factor secreted?
Your Answer: Gastric parietal cells
Explanation:Intrinsic factor (IF), also known as gastric intrinsic factor (GIF), is a glycoprotein produced by the parietal cells of the stomach. It is necessary for the absorption of vitamin B12 (cobalamin) later on in the small intestine.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 27
Correct
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Regarding CSF:
Your Answer: Disruption of arachnoid villi function results in a communicating hydrocephalus
Explanation:In normal adults CSF volume is around 125ml to 150ml. Turnover of the entire volume of cerebrospinal fluid is about 3 to 4 times a day. Composition of CSF is similar to that of plasma except that CSF is nearly protein-free compared with plasma and has different electrolyte levels. Blockage of the foramina causes an obstructive or non-communicating hydrocephalus. Communicating hydrocephalus or non-obstructive hydrocephalus is caused by impaired CSF reabsorption in the absence of any CSF flow obstruction.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 28
Correct
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Where does the SA node develop?
Your Answer: From structures on the right side of the embryo.
Explanation:The SA node develops from the right side of the embryo and the AV node from the left. This is the reason why in adults the right vagus supplies the SA node and the left vagus supplies the AV node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 29
Correct
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In most somatic cells telomeres progressively shorten as:
Your Answer: The cell divides
Explanation:Telomere length shortens with age. Progressive shortening of telomeres leads to senescence, apoptosis, or oncogenic transformation of somatic cells, affecting the health and lifespan of an individual. Telomeres prevent the chromosomes from shortening and prevent the coding portion of the DNA from being lost, thus allowing the cell to replicate indefinitely. During replication telomeres may be lost resulting in cell death.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 30
Correct
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The HIV virus:
Your Answer: P24 is a core protein
Explanation:HIV is different in structure from other retroviruses. It is roughly spherical with a diameter of about 120 nm, around 60 times smaller than a red blood cell. It is composed of two copies of positive single-stranded RNA that codes for the virus’s nine genes enclosed by a conical capsid composed of 2,000 copies of the viral protein p24. The single-stranded RNA is tightly bound to nucleocapsid proteins, p7, and enzymes needed for the development of the virion such as reverse transcriptase, proteases, ribonuclease and integrase. A matrix composed of the viral protein p17 surrounds the capsid ensuring the integrity of the virion particle. Reverse transcriptase copies the viral single stranded RNA genome into a double-stranded viral DNA.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 31
Correct
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Which of the following structures of the cardiac conduction system is located in the right posterior portion of the interatrial septum?
Your Answer: AV node
Explanation:AV node is located at the right posterior portion of the interatrial septum.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 32
Correct
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In which organ will you find extremely porous sinusoidal capillaries, with discontinuous endothelium?
Your Answer: Liver
Explanation:The liver is the organ which contains sinusoidal capillaries with discontinuous endothelium. The brain, lungs and the intestine all contain continuous capillaries, however the kidney contains fenestrated capillaries to aid in filtration.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 33
Correct
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Cyclic AMP is formed from ATP via which enzyme
Your Answer: Adenylate cyclase
Explanation:Cyclic AMP is synthesized from ATP by adenylate cyclase located on the inner side of the plasma membrane and anchored at various locations in the interior of the cell.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 34
Correct
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Which of the following substances inhibits pancreatic secretion?
Your Answer: Pancreatic polypeptide
Explanation:Number of hormones and neurotransmitters can stimulate and inhibit pancreatic exocrine secretion. Cholecystokinin, secretin, vasoactive intestinal peptide and substance P stimulate pancreatic secretion. Pancreatic polypeptide, somatostatin inhibit pancreatic secretion.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 35
Correct
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The Plateau phase in myocyte action potentials does all of the following except:
Your Answer: It allows early reactivation of the myocytes
Explanation:The presence of the plateau in the action potential causes ventricular contraction to last as much as 15 times longer in cardiac muscle as in skeletal muscle. The plateau phase which follows is unique to myocytes and results from a small, but sustained inward calcium current through L-type calcium channels lasting 200-400 ms. This calcium influx is caused by a combined increase in permeability of the cell and especially the sarcolemmal membranes to calcium. This plateau (refractory) phase prevents early reactivation of the myocytes and directly determines the strength of contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 36
Correct
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Cholecystokinin causes the pancreas to
Your Answer: Produce pancreatic juice rich in enzymes
Explanation:Cholecystokinin (CCK) mediates digestion in the small intestine by inhibiting gastric emptying and decreasing gastric acid secretion. It stimulates the acinar cells of the pancreas to release a juice rich in pancreatic digestive enzymes, hence the old name pancreozymin. Together these enzymes catalyse the digestion of fat, protein, and carbohydrates.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 37
Correct
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An example of cholinergic autonomic neurons are:
Your Answer: Sympathetic postganglionic neurons that innervate sweat glands.
Explanation:All preganglionic neurons in both the sympathetic and parasympathetic nervous system secrete acetylcholine. The postganglionic neurotransmitter of the parasympathetic nervous system in all neurons is acetylcholine. Postganglionic fibers of the sympathetic nervous system mainly secrete Noradrenalin and Adrenalin but at sweat glands and erector pili muscles the postganglionic neurotransmitter is acetylcholine.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 38
Correct
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Concerning S3, which of the following statements is INCORRECT?
Your Answer: Coincide with atrial contraction
Explanation:A third heart sound also called a ventricular gallop occurs at the beginning of diastole after S2 and is lower in pitch than S1 or S2 as it is not of valvular origin. The third heart sound is benign in youth, some trained athletes, and sometimes in pregnancy but if it re-emerges later in life it may signal cardiac problems, such as a failing left ventricle as in dilated congestive heart failure (CHF). S3 is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by blood rushing in from the atria. The reason the third heart sound does not occur until the middle third of diastole is probably that during the early part of diastole, the ventricles are not filled sufficiently to create enough tension for reverberation. It may also be a result of tensing of the chordae tendineae during rapid filling and expansion of the ventricle. In other words, an S3 heart sound indicates increased volume of blood within the ventricle. An S3 heart sound is best heard with the bell-side of the stethoscope (used for lower frequency sounds). A left-sided S3 is best heard in the left lateral decubitus position and at the apex of the heart, which is normally located in the 5th left intercostal space at the midclavicular line. A right-sided S3 is best heard at the lower-left sternal border. The way to distinguish between a left and right-sided S3 is to observe whether it increases in intensity with inhalation or exhalation. A right-sided S3 will increase on inhalation, while a left-sided S3 will increase on exhalation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 39
Correct
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Microtubule disassembly:
Your Answer: Occurs at the positive and negative end
Explanation:Dynamic instability refers to the coexistence of assembly and disassembly at the ends of a microtubule. The microtubule can dynamically switch between growing and shrinking phases in this region. Although both assembly and disassembly occur at both ends they occur preferentially at the (+) end.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 40
Correct
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Which is true of the citric acid cycle?
Your 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
- Medicine
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Question 41
Correct
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In cardiac muscle, which of the following is directly responsible for the release of Ca2+ stored in the sarcoplasmic reticulum (calcium-induced calcium release)?
Your Answer: Ryanodine receptor (RyR)
Explanation:Ryanodine receptor (RyR) is a ligand-gated Ca2+ channel with Ca2+ as its natural ligand. In skeletal muscle, Ca2+ entry from ECF by this route is not required for Ca2+ release. Instead, the DHPR that serves as the voltage sensor unlocks release of Ca2+ from the nearby SR via physical interaction with the RyR. The release is amplified through ca-induced ca release. However, in cardiac muscle, it is the influx of extracellular Ca2+ through the voltage-sensitive DHPR in the T system that triggers ca-induced ca release trough the RyR at the SR.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 42
Incorrect
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Which one of the following conditions is least likely to be associated with pyoderma gangrenosum?
Your Answer: Rheumatoid arthritis
Correct Answer: Syphilis
Explanation:The following are conditions commonly associated with pyoderma gangrenosum:
Inflammatory bowel disease:
- Ulcerative colitis
- Crohn’s disease
Arthritides:
- Rheumatoid arthritis
- Seronegative arthritis
Haematological disease:
- Myelocytic leukaemia
- Hairy cell leukaemia
- Myelofibrosis
- Myeloid metaplasia
- Monoclonal gammopathy
Autoinflammatory disease:
- Pyogenic sterile arthritis, pyoderma gangrenosum, and acne syndrome (PAPA syndrome)
- Granulomatosis with polyangiitis
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 43
Correct
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Which of the following pairing is correct:
Your Answer: Herpes simplex type I and herpes encephalitis
Explanation:Herpes simplex virus is likely the most common cause of Mollaret’s meningitis, and, in worse case scenarios, can lead to a potentially fatal case of herpes simplex encephalitis. The eighth human herpesvirus or HHV-8 causes Kaposi’s sarcoma and Herpes simplex type 2 is responsible for most primary genital herpes.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 44
Correct
-
Neurogenesis occurs throughout life in the following two areas:
Your Answer: Hippocampus and striatum
Explanation:In humans, neurogenesis or new neurons are continually born during adulthood in two regions of the brain: The subgranular zone (SGZ), part of the dentate gyrus of the hippocampus and the striatum. In other species of mammals, adult-born neurons also appear in the olfactory bulb. In humans, however, few if any olfactory bulb neurons are generated after birth.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 45
Correct
-
Which enzyme is responsible for the removal of acetylcholine from the synapse?
Your Answer: Acetylcholinesterase
Explanation:Acetylcholinesterase is the enzyme that is responsible for breaking down acetylcholine into choline and acetate. Both of these molecules are transported back to the presynaptic neuron to be synthesized again. This enzyme is attached to the collagen fibers of the basement membrane in the synaptic cleft.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 46
Incorrect
-
In a patient with prostate cancer, what is the mechanism by which goserelin acts?
Your Answer: GnRH antagonist
Correct Answer: GnRH agonist
Explanation:Androgen deprivation therapy (ADT) for prostate cancer:Goserelin (Zoladex) is a synthetic gonadotropin-releasing hormone (GnRH) analogue; chronic stimulation of goserelin results in suppression of LH, FSH serum levels thereby preventing a rise in testosterone.Dosage form: 3.6 mg/10.8mg implants.Adverse effects include flushing, sweating, diarrhoea, erectile dysfunction, less commonly, rash, depression, hypersensitivity, etc.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 47
Correct
-
A 67 year old man reports weight loss. Labs show a raised alkaline phosphatase at 290 U/L (normal range 35-120). Plain radiographs reveal sclerotic lesions of the bone. Which of the following is the most likely cause of these findings?
Your Answer: Prostate cancer
Explanation:Osteoblastic (or sclerotic) bony metastases, characterized by deposition of new bone, present in prostate cancer, carcinoid, small cell lung cancer, Hodgkin lymphoma or medulloblastoma. The other cancers listed in the options are osteolytic.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 48
Incorrect
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Which of the following best describe N. Meningitides?
Your Answer: Gram positive cocci
Correct Answer: Gram negative cocci
Explanation:Neisseria meningitidis, often referred to as meningococcus, is a gram negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcaemia, a life-threatening sepsis. The bacterium is referred to as a coccus because it is round, and more specifically, diplococcus because of its tendency to form pairs. About 10% of adults are carriers of the bacteria in their nasopharynx.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 49
Incorrect
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A 50-year-old male presents to the ER allegedly claiming that he consumed a bottle of antifreeze. Which of the following symptoms is least likely to be associated with this kind of poisoning?
Your Answer: Loss of vision
Correct Answer: Hypertension
Explanation:Loss of vision after consumption of antifreeze is a characteristic presentation of methanol poisoning.
Pathophysiology of methanol toxicity: When ingested, methanol is absorbed rapidly via the gastrointestinal tract in less than 10 minutes. Methanol is not protein-bound and is absorbed directly into the total body water compartment. Metabolism occurs mainly in the liver through serial oxidation via alcohol dehydrogenase and aldehyde dehydrogenase but begins with alcohol dehydrogenase present in the gastric mucosa. Alcohol dehydrogenase oxidizes methanol to formaldehyde, and aldehyde dehydrogenase subsequently oxidizes formaldehyde to formic acid. Formic acid is the primary toxic metabolite that accounts for the associated anion gap metabolic acidosis and end-organ damage.
Clinical presentation: Patients who present within the first 12 to 24 hours following ingestion may appear normal, and this is described as the latent period. Nausea, vomiting, and abdominal pain subsequently ensue, followed by CNS depression and hyperventilation due to metabolic acidosis. Ocular symptoms associated with retinal toxicity are often evident in the form of blurry vision, decreased visual acuity, photophobia, and “halo vision.”
Treatment: Treatment options for methanol toxicity include supportive care, fomepizole (Antizole, 4-Methylpyrazole or 4MP), ethanol, dialysis, and folate.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 50
Correct
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The consensual light reflex is co-ordinated mainly in the:
Your Answer: Edinger-Westphal nucleus
Explanation:The consensual light reflex occurs when an individual’s right eye is shielded and light shines into the left eye, constriction of the right pupil will occur, as well as the left. This is because the afferent signal sent through one optic nerve connects to the Edinger-Westphal nucleus, whose axons run to both the right and the left oculomotor nerves.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 51
Correct
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Question 52
Incorrect
-
The actions of thrombin result directly in the release of:
Your Answer: Fibrin dimers
Correct Answer: Fibrin monomers
Explanation: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
- Medicine
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Question 53
Correct
-
Which intercellular connections are responsible for fastening the cells to one another?
Your Answer: Hemidesmosomes, zonula adherens & desmosomes
Explanation:There are three major types of cell junction:Adherens junctions, desmosomes and hemidesmosomes (anchoring junctions),Gap junctions (communicating junction) &Tight junctions (occluding junctions)
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 54
Incorrect
-
The process by which DNA fragments are separated by gel and transferred onto a membrane sheet is called:
Your Answer: Northern blotting
Correct Answer: Southern blotting
Explanation:A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization. The other forms of blotting involve the use of RNA and proteins.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 55
Incorrect
-
A 75-year-old man has presented to the clinic with a complaint of disturbed sleep. The physician has prescribed temazepam. Which of the following best describes the mechanism of action of this drug?
Your Answer: Inhibits the effect gamma-aminobutyric acid
Correct Answer: Enhances the effect of gamma-aminobutyric acid
Explanation:Temazepam is an orally available benzodiazepine used in the therapy of insomnia. The soporific activity of the benzodiazepines is mediated by their ability to enhance gamma-aminobutyric acid (GABA) mediated inhibition of synaptic transmission through binding to the GABA-A receptor.The recommended initial dose for insomnia is 7.5 mg before bedtime, increasing as needed to a maximum dose of 30 mg. The most common side effects of temazepam are dose-related and include daytime drowsiness, lethargy, ataxia, dysarthria, and dizziness.Tolerance develops to these side effects, but tolerance may also develop to the effects on insomnia.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 56
Correct
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A 50-year-old man with a history of hyperlipidaemia, currently under treatment with simvastatin 10mg was found to have persistently high cholesterol levels. Previous attempts to increase the dose of simvastatin have resulted in myalgia. Given this history, which one of the following lipid-regulating drugs should definitely be avoided?
Your Answer: Bezafibrate
Explanation:Both fibrates and nicotinic acid have been associated with myositis, especially when combined with a statin. However, the Committee on Safety of Medicines has produced guidance which specifically warns about the concomitant prescription of fibrates with statins concerning muscle toxicity.Bezafibrate: It is a fibric acid derivative (fibrate) that has been used as a class of agents known to decrease triglyceride levels while substantially increasing HDL-C levels.Pharmacological effects:- Increases VLDL catabolism by increasing lipoprotein and hepatic triglyceride lipase.- Decreases triglyceride synthesis by inhibiting acetyl-CoA reductase.- Decreases cholesterol synthesis by inhibiting HMG-CoA reductase.Side effects:- Hypersensitivity- Primary biliary cirrhosis- Pre-existing gallbladder disease- Concurrent use with HMG-CoA inhibitors (statins) can produce myopathy- Hepatic/renal impairment in a patient warrants dose adjustment as this drug is primarily excreted via the renal mechanism.Contraindications: Concurrent use of MAO inhibitors, hypersensitivity, pre-existing cholestasis, and pregnancy.Use: It can be used to treat Barth syndrome (characterized by dilated cardiomyopathy, neutropenia (presenting with recurrent infections), skeletal myopathy and short stature)
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 57
Correct
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Question 58
Correct
-
Which neuron secretes glutamate as its neurotransmitter?
Your Answer: A delta and C pain fibers
Explanation:A delta and C fibers use glutamate as their primary neurotransmitter where it acts as a fast acting localized neurotransmitter.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 59
Correct
-
An exaggerated response to a noxious stimulus is called:
Your Answer: Hyperalgesia
Explanation:Allodynia is the sensation of pain following non-painful stimulation.
Hyperalgesia is enhanced intensity of pain sensation.
Causalgia is a constant burning pain resulting from peripheral nerve injury.
Hyperesthesia is the abnormal increase in sensitivity to stimuli of sense.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 60
Correct
-
In addition to its role in digestion and absorption of fats, bile:
Your Answer: Is the major excretory route for lipid-soluble waste products
Explanation:The end product of haem metabolism is bilirubin and jaundice is caused by increased bilirubin levels in the blood. Gallstones are mainly caused by cholesterol and bile pigments. Bile is the main route of excretion for lipid soluble waste products whereas urine is the main route of excretion of water soluble waste products.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 61
Correct
-
What effect does osmotic diuresis have on net Na+ excretion?
Your Answer: Markedly increased Na+ excretion
Explanation:Osmotic diuresis is the increase of urination rate caused by the presence of certain substances in the small tubes of the kidneys. The excretion occurs when substances such as glucose enter the kidney tubules and cannot be reabsorbed (due to a pathological state or the normal nature of the substance). The substances cause an increase in the osmotic pressure within the tubule, causing retention of water within the lumen, and thus reduces the reabsorption of water, increasing urine output (i.e. diuresis). Sodium, chloride, potassium are markedly excreted in osmotic diuresis.
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This question is part of the following fields:
- Medicine
- Renal
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Question 62
Incorrect
-
Regarding bronchial innervation which of the following is correct:
Your Answer: Beta 2 receptors mediate bronchoconstriction
Correct Answer: Alpha 1 receptors increase bronchial constriction
Explanation:Stimulation of β2 receptors results in smooth muscle relaxation and bronchodilation. α1 receptors cause smooth muscle contraction in the bronchioles although minor to the β2 effects.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 63
Correct
-
The following is true of the sinus node:
Your Answer: It generates impulses automatically & at a quicker rate than other cardiac cells
Explanation:The SA node exhibits automaticity. It generates the impulses to which the heart beats. It fires at a faster speed than the rest of the nervous components of the heart i.e. the AV nodes, purkinje fibers. This is the reason when the SA node fails the heart beats to the rhythm of the AV node.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 64
Correct
-
Which statement is correct regarding mRNA?
Your Answer: mRNAs are mainly found in the nucleus and cytoplasm of a cell.
Explanation:mRNA is transcribed from DNA and is carried to the cytosol to be translated. Hence it is mainly found in the cytosol and the nucleus of a cell. It is single stranded and contains the base uracil instead of thymine.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 65
Correct
-
Which of the following conditions has no effect on cardiac output?
Your Answer: Sleep
Explanation:Sleep has no effect on the cardiac output. Anxiety, excitement and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 66
Correct
-
Regarding Polymerase Chain Reaction, all are true except:
Your Answer: There is a linear rise of DNA copies during amplification.
Explanation:All are true except there is a linear rise of DNA copies during amplification. There is an exponential rise in amplification of DNA.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 67
Correct
-
Which of the following is responsible for converting inactive cortisone to active cortisol in the adrenal gland?
Your Answer: 11βHSD type 1
Explanation:11β-Hydroxysteroid dehydrogenase, also known as HSD-11β or 11β-HSD, is a group of enzymes which catalyse the interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 68
Correct
-
The residual cleft of the intermediate lobe of the pituitary is lined by follicles resembling which human gland?
Your Answer: Thyroid
Explanation:The cells located between the two main pituitary lobes form what is known as the intermediate pituitary. This area secretes melanocyte-stimulating hormone and it is only a few cell layers thick. It is rich in follicles filled with colloid, and lined by basophilic cells. This configuration resembles that of another important gland: the thyroid.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 69
Correct
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Where does secretin work in the pancreas?
Your Answer: Pancreatic ducts
Explanation:Secretin, a hormone produced by the duodenal S cells in response to the stomach chyme containing high hydrogen atom concentration (high acidity), is released into the blood stream; upon return to the digestive tract, secretion decreases gastric emptying, increases secretion of the pancreatic ductal cells, as well as stimulating pancreatic acinar cells to release their zymogenic juice.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 70
Correct
-
Which of the following is not true regarding mitochondrial chromosome disorders?
Your Answer: Because mitochondrial chromosomes have no introns in their genes, any point mutation has a low likelihood of having an effect.
Explanation:Mitochondrial DNA (mtDNA) does indeed lack introns, meaning that its genes are closely packed with coding sequences. This actually means that any point mutation in the mtDNA is more likely to have an effect, not less. The lack of introns means there are fewer non-coding regions where mutations can occur without affecting gene function. Thus, mutations in mtDNA often have significant consequences because they are more likely to alter essential coding sequences.
The other statements are true:
- Most mitochondrial diseases are myopathies and neuropathies with a maternal pattern of inheritance: This is correct because mtDNA is inherited maternally, and many mitochondrial disorders affect muscle and nerve function.
- Retinal degeneration, diabetes mellitus, and some forms of hearing loss are some of the other diseases attributed to mitochondrial chromosome defects: These are indeed conditions associated with mitochondrial defects.
- Mitochondrial chromosome defects are inherited from one’s mother: This is correct, as mtDNA is passed from mother to offspring.
- Leber’s hereditary optic neuropathy (LHON), the commonest cause of blindness in young men, is an example of a mitochondrial chromosome defect: This is true; LHON is a well-known mitochondrial disorder.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 71
Correct
-
What is the mechanism of action of sumatriptan?
Your Answer: 5-HT1 agonist
Explanation:Triptans are specific 5-HT1 agonists used in the acute treatment of migraine. They are generally used as first-line therapy in combination with an NSAID or paracetamol.
Sumatriptan acts as an agonist on 5-HT1B/1D receptors by inducing vasoconstriction in the basilar artery and blood vessels within the dura mater. The drug reduces peripheral nociception either by selective cranial vasoconstriction or by affecting trigeminovascular nerves.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 72
Correct
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A 42-year-old female with type 1 diabetes who has undergone a renal transplant is being reviewed. She is taking azathioprine and tacrolimus for immunosuppression.Which among the following is correct regarding the given immunosuppressive agents?
Your Answer: Tacrolimus is a calcineurin inhibitor
Explanation:Tacrolimus is a calcineurin inhibitor used as an immunosuppressive agent used for prophylaxis of organ rejection post-transplant.Pharmacology: Calcineurin inhibition leads to reduced T-lymphocyte signal transduction and IL-2 expression. It has a half-life of 12 hours (average).Other off-label indications for the use of tacrolimus include Crohn disease, graft-versus-host disease (GVHD), myasthenia gravis, rheumatoid arthritis.Adverse effects of tacrolimus includes: Cardiovascular: Angina pectoris, cardiac arrhythmias, hypertensionCentral nervous system: Abnormal dreams, headaches, insomnia, tremors.Dermatologic: Acne vulgaris, alopecia, pruritis, rashEndocrine and metabolic: Decreased serum bicarbonate, decreased serum iron, new-onset diabetes mellitus after transplant (NODAT), electrolyte disturbances.Gastrointestinal: Abdominal pain, nausea, vomiting, diarrhoeaGenitourinary: Urinary tract infectionHepatic: Abnormal hepatic function testsNeuromuscular and skeletal: Arthralgia, muscle crampsOphthalmic: Blurred vision, visual disturbanceOtic: Otalgia, otitis media, tinnitusRenal: Acute renal failureOther options:Sirolimus (a macrolide) is an mTOR inhibitor that blocks the response to IL-2 and has a half-life of 12–15 hours. Azathioprine inhibits purine synthesis, an essential step in the proliferation of white cells and has a half-life of around 5 hours.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 73
Correct
-
Acetylcholine from enteric nerve endings stimulates this pair:
Your Answer: Parietal cells and chief cells
Explanation:In the body of the stomach, the vagal postganglionic muscarinic nerves release acetylcholine(ACh) which stimulates parietal cell H+ secretion. Gastric chief cells are primarily activated by ACh. However the decrease in pH caused by activation of parietal cells further activates gastric chief cells.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 74
Correct
-
Which of the following factors serve to decrease cardiac output?
Your Answer: Standing from a lying position
Explanation:Sleep has no effect on the cardiac output. Anxiety, excitement, increased body temperature and pregnancy will increase the cardiac output. Standing from a lying position will decrease the cardiac output transiently.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 75
Correct
-
The infoldings or spaces between the bases of the villi are known as
Your Answer: Crypts of Lieberkühn
Explanation:An intestinal gland (also crypt of Lieberkühn and intestinal crypt) is a gland found in the intestinal epithelium lining of the small intestine and large intestine (colon) between the villi.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 76
Incorrect
-
The reticular formation occupies which area of the brain?
Your Answer: Pre-frontal cortex
Correct Answer: Medulla and midbrain
Explanation:The reticular formation is a set of interconnected nuclei that are located along the brainstem.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 77
Correct
-
The alpha amylases hydrolyse which linkages in the ingested polysaccharides?
Your Answer: 1:4α linkages
Explanation:Alfa amylase hydrolyses the α (1-4) glyosidic bonds in amylose and amylopectin and leave primarily maltose.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 78
Correct
-
The basic unit of contraction in myocytes is:
Your Answer: Sarcomere
Explanation:Sarcomere is the organelle where calcium is stored to be released during contraction of the muscle. It is the basic unit of contraction in striated muscle fibers. As myocytes are also striated muscles, sarcomeres also forms the basic unit of contraction. The impulses travel along the membrane and via its interaction with the dihydropyridine receptors it releases the stored calcium.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 79
Correct
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Question 80
Correct
-
Gastrin activates all of the following cells except:
Your Answer: Mucus neck cells
Explanation:The G cell is a type of cell in the stomach and duodenum that secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. G cells are found deep within the pyloric glands of the stomach antrum, and occasionally in the pancreas and duodenum. Gastrin-releasing peptide, as well as the presence of amino acids in the stomach, stimulates the release of gastrin from the G cells. Gastrin stimulates enterochromaffin-like cells to secrete histamine. Gastrin also targets parietal cells by increasing the amount of histamine and the direct stimulation by gastrin, causing the parietal cells to increase HCl secretion in the stomach.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 81
Correct
-
A 42 year old obese man complains of a painful swollen ankle. The pain has worsened over the past 2 weeks. He is a diabetic and gives a history of recent alcohol consumption. Joint aspirate shows rhomboid crystals with numerous neutrophils. Radiological examination shows evidence of chondrocalcinosis. Which of the following is the most likely diagnosis?
Your Answer: Pseudogout
Explanation:Pseudogout is a paroxysmal joint inflammation due to calcium pyrophosphate crystal deposition (calcium pyrophosphate dihydrate). Aetiology includes mostly idiopathic (primary form) and secondary form occurring as a result of joint trauma, familial chondrocalcinosis, hyperparathyroidism, hemochromatosis, gout, hypophosphatemia. Clinical presentation: Often asymptomatic. Acute (pseudogout attack): monoarthritis (rarely oligoarthritis), mostly affecting the knees and other large joints (e.g., hips, wrists, and ankles). It may become chronic (can affect multiple joints). Osteoarthritis with CPPD (most common form of symptomatic CPPD): progressive joint degeneration with episodes of acute inflammatory arthritis typical of pseudogout attacks. Arthrocentesis should be performed, especially in acute cases. Polarized light microscopy: detection of rhomboid-shaped, positively birefringent CPPD crystals. Synovial fluid findings: 10,000-50,000 WBCs/μL with > 90% neutrophils. X-ray findings: cartilage calcification of the affected joint (chondrocalcinosis). Fibrocartilage (meniscus, annulus fibrosus of intervertebral disc) and hyaline cartilage (joint cartilage) may be affected.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 82
Incorrect
-
The pontine tegmentum as part of the midbrain, contains which cranial nerve nuclei?
Your Answer: CN 3 to 5
Correct Answer: CN 5 to 8
Explanation:The pontine tegmentum also known as dorsal pons is located within the brain stem. Several cranial nerve nuclei are located in the pontine tegmentum. The nuclei of CN V, CN VI, CN VII and CNVIII are located in the pontine tegmentum.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 83
Correct
-
Which of the following regulates the calcium release channels?
Your 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
- Medicine
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Question 84
Correct
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Question 85
Correct
-
The enzyme located on the brush border of the small intestine activating the proteolytic enzymes for further digestion of proteins is called?
Your Answer: Enterokinase
Explanation:Enterokinase is a brush border enzyme of the duodenum that activates proteolytic enzymes for further digestion of proteins. Trypsinogen is converted to trypsin by the action of enterokinase. Trypsin and chymotrypsin are secreted by the pancreatic acinar cells and are enzymes that aid in protein digestion. Pepsin is secreted by chief cells of the gastric mucosa. Procarboxydase is the inactive form of carboxypeptidase which is converted to its active form by trypsin and is secreted by pancreatic acinar cells.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 86
Correct
-
A cohort study is developed to assess the correlation between blood pressure and working long hours. After 10 years of follow-up and for the 1050 individuals working less than 40 hours per week, 1000 patients had normal blood pressure and 50 patients were diagnosed with hypertension. For the 660 patients working more than 40 hours per week, 600 patients had normal blood pressure and 60 patients were diagnosed with hypertension. If you work more than 40 hours per week, what is the odds ratio of developing hypertension compared to the individuals working less than 40 hours per week?
Your Answer: 2
Explanation:An odds ratio (OR) is a measure of the association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Wherea = Number of exposed casesb = Number of exposed non-casesc = Number of unexposed casesd = Number of unexposed non-casesOR=(a/c) / (b/d) = ad/bc
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 87
Correct
-
A case-control study is developed to assess passive smoking as a risk factor for the development of asthma in children. The total number of patients recruited for this study is 200. 40 out of the 200 patients report at least one parent smoking in the house when they were younger. 200 more people without asthma are recruited and 20 out of them report that at least one parent smoked in the house when they were younger. What is the odds ratio of patients with asthma having been exposed to passive smoking during their childhood?
Your Answer: 2.25
Explanation:An odds ratio (OR) is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Wherea = Number of exposed casesb = Number of exposed non-casesc = Number of unexposed casesd = Number of unexposed non-casesOR=(a/c) / (b/d) = ad/bc
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 88
Correct
-
In the basal ganglia, the Lentiform nucleus is formed by which two nuclei?
Your Answer: Putamen and Globus pallidus
Explanation:The Basal Ganglia are composed of the following structures: Caudate, putamen, Globus pallidus, subthalamic nucleus and substantia nigra.
The Lentiform nucleus is a biconvex structure located within the basal ganglia of the brain. It is composed of two nuclei:
- Putamen: This is the outer part of the Lentiform nucleus and is involved in regulating movements and various types of learning.
- Globus pallidus: This is the inner part of the Lentiform nucleus and is divided into two segments: the external segment (GPe) and the internal segment (GPi). It plays a key role in the regulation of voluntary movement.
These two structures together form the Lentiform nucleus, which is an integral part of the basal ganglia system involved in motor control.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 89
Correct
-
The following occurs as a result of 2,3 Bisphosphoglycerate binding to deoxyhaemoglobin
Your Answer: A reduction in deoxyhaemoglobin's affinity for oxygen
Explanation:2,3-BPG acts as a heteroallosteric effector of haemoglobin, lowering haemoglobin’s affinity for oxygen by binding preferentially to deoxyhaemoglobin. An increased concentration of BPG in red blood cells favours formation of the T, low-affinity state of haemoglobin and so the oxygen-binding curve will shift to the right.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 90
Correct
-
Question 91
Correct
-
When one of the two copies of the autosomes has a mutation and the protein produced by the normal form of the gene cannot compensate. The affected individual has an:
Your Answer: Autosomal dominant disorder
Explanation:An autosomal dominant trait will be expressed no matter the consequence. If one chromosome has a mutation the other will not be able to compensate for the mutation hence the protein formed will be mutated and will not function properly.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 92
Incorrect
-
The following are Gram positive rods:
Your Answer: Klebsiella
Correct Answer: Clostridia
Explanation:Examples of Gram positive bacilli:Bacillus genusClostridium genusCorynebacterium genusListeria genusPropionibacterium genusExamples of Gram negative bacilli:Bacteroides genusCitrobacter genusEnterobacter genusEscherichia genusPseudomonas genusProteus genusSalmonella genusSerratia genusShigella genusYersinia genus
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 93
Correct
-
The enzyme that catalyses the final step in glycogen synthesis is:
Your Answer: Glycogen synthase
Explanation:Glycogen synthase is a key enzyme in glycogenesis, the conversion of glucose into glycogen. This enzyme combines excess glucose residues one by one into a polymeric chain for storage as glycogen.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 94
Correct
-
Where in the course of the gastrointestinal tract does the first significant digestion of fat begin in a normal human being?
Your Answer: Duodenum
Explanation:The enzyme lipase which is responsible for digestion of fat is secreted by the exocrine pancreas in the 2nd part of the duodenum at the point where the pancreatic duct opens. It opens together with the common bile duct which contains bile that emulsify fat aiding in digestion. The oesophagus, stomach and mouth do not contain enzymes related to fat digestion.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 95
Correct
-
Question 96
Correct
-
A deficiency in Niacin leads to which clinical deficiency syndrome?
Your Answer: Pellagra
Explanation:Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhoea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over time affected skin may become darker, stiff, begin to peel, or bleed.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 97
Correct
-
Organophosphates, such as Sarin, have been used as chemical-warfare agents by terrorists. Which of the following statements is true concerning organophosphate poisoning?
Your Answer: Atropine is useful in the management of organophosphate poisoning
Explanation:The principal action of organophosphates is the inhibition of acetylcholinesterase’s, therefore leading to the accumulation of acetylcholine at muscarinic receptors (miosis, hypersalivation, sweating, diarrhoea, excessive bronchial secretions), nicotinic receptors (muscle fasciculations and tremor) and in the central nervous system (anxiety, loss of memory, headache, coma). Removal from the source of the organophosphate, adequate decontamination, supplemental oxygen and atropine are the initial treatment measures. Pralidoxime, an activator of cholinesterase, should be given to all symptomatic patients.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 98
Correct
-
Which clotting factor is responsible for stabilization of the fibrin clot by formation of covalent cross-linkages?
Your Answer: Factor XIIIa
Explanation:Factor XIII or fibrin stabilizing factor is an enzyme of the blood coagulation system that crosslinks fibrin. Deficiency of this factor (FXIIID) affects clot stability.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 99
Correct
-
Which enzyme is deficient in the inborn error of metabolism called galactosemia?
Your Answer: Galactose-1-phosphate uridyl transferase
Explanation:Galactosaemia is a rare genetic autosomal recessive metabolic disorder. Lactose is broken down by the enzyme lactase into glucose and galactose. In individuals with galactosemia, the enzymes needed for further metabolism of galactose (Galactose-1-phosphate uridyltransferase) are severely diminished or missing entirely, leading to toxic levels of galactose 1-phosphate in various tissues.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 100
Correct
-
A 46 year old male, known with Rheumatoid Arthritis presents with a swollen and painful right ankle. No drug allergies are reported. On examination, the vitals are as follows: Temp: 38.8BP: 90/60 mmHgPulse: 110/min. Right ankle examination reveals tenderness, warmth, erythema and tense joint effusion. Blood samples including blood cultures are collected and fluid resuscitation is initiated. Which of the following interventions would be most appropriate for this man?
Your Answer: Administer i.v. flucloxacillin, and arrange joint aspiration urgently
Explanation:Although microscopic analysis of joint fluid aspirate and culture is the basis of septic arthritis diagnosis and should usually be collected before the administration of antibiotics, the patient is showing signs of septic shock. A delay in antibiotics might lead to worsening of symptoms so they are administered first.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 101
Incorrect
-
A patient who has recently been diagnosed with SLE undergoes serum testing. A rise in which of the following antibodies would indicate severe systemic involvement?
Your Answer: Anticardiolipin antibodies
Correct Answer: Anti double-stranded DNA antibodies
Explanation:Anti ds-DNA antibodies are very specific for SLE and their presence most often indicates systemic spread of the disease. These antibodies are present in about 30 percent of the total cases of SLE.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 102
Incorrect
-
A 64 year old woman who is of Asian descent and is diabetic (controlled by diet) presents with generalized body aches and difficulty rising from sitting for the last few months. Her blood glucose levels are in the normal range. Lab examination reveals normal blood cell count, low serum phosphate, calcium at the lower range, and raised alkaline phosphatase levels. Radiological examination shows which of the following?
Your Answer: Osteolytic areas with bone destruction
Correct Answer: Linear areas of low density
Explanation:Osteomalacia is a condition due to defective mineralization of osteoid. Occurs as a result of Vitamin D deficiency secondary to poor dietary intake and sun exposure, malabsorption e.g., inflammatory bowel disease and gastrointestinal bypass surgery. Radiological findings include reduced bone mineral density (a non specific finding), inability to radiologically distinguish vertebral body trabeculae (the film appears poor quality), looser pseudo fractures, fissures, or narrow radiolucent lines (these are the characteristic findings). Osteolytic or punched out lesions may be seen with multiple myeloma and bony metastases. Areas of sclerosis may be observed with conditions like osteosclerosis and Paget disease. A Brodie abscess is a subacute osteomyelitis, which may persist for years before progressing to a chronic, frank osteomyelitis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 103
Correct
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Question 104
Correct
-
Which of the following drugs requires plasma level monitoring?
Your Answer: Vancomycin
Explanation:All patients require plasma-vancomycin measurement (after 3 or 4 doses if renal function normal, earlier if renal impairment). There is a risk of nephrotoxicity including renal failure, interstitial nephritis and ototoxicity.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 105
Incorrect
-
Protein digestion starts in the stomach by which enzyme?
Your Answer: Amylase
Correct Answer: Pepsin
Explanation:Pepsinogen is the inactive form of pepsin which is secreted by gastric chief cells and is converted to pepsin, in the presence of gastric HCL. Pepsin is a peptidase that breaks down proteins into smaller peptides.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 106
Correct
-
Which of the following features is least commonly seen in Gitelman’s syndrome?
Your Answer: Hypertension
Explanation:Gitelman syndrome is an autosomal recessive kidney disorder characterized by hypokalaemia metabolic alkalosis with hypocalciuria, and hypomagnesemia. In contrast to patients with Gordon’s syndrome, those suffering from Gitelman’s syndrome are generally normotensive or hypotensive.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 107
Correct
-
What is the function of cytotoxic T cells?
Your Answer: Kill by inserting perforins and by initiating apoptosis
Explanation:Cytotoxic T cells, once activated, approach the infected cell, insert perforins and release granzymes inducing apoptosis.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 108
Correct
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The amount of a substance taken up by an organ (or whole body) per unit time is = (the arterial level - the venous level) * the blood flow. This statement describes?
Your Answer: The Fick principle
Explanation:The essence of the Fick principle is that blood flow to an organ can be calculated using a marker substance if the following information is known:- Amount of marker substance taken up by the organ per unit time- Concentration of marker substance in arterial blood supplying the organ- Concentration of marker substance in venous blood leaving the organ
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 109
Correct
-
Lipid- lowering drugs like Lovastatin reduce cholesterol synthesis by inhibiting which enzyme?
Your Answer: HMG-CoA reductase
Explanation:Statins, also known as HMG-CoA reductase inhibitors, are a class of lipid-lowering medications. Statins have been found to reduce cardiovascular disease (CVD) and mortality in those who are at high risk.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 110
Correct
-
A 68 year old male, previously diagnosed with osteoarthritis presents to your clinic with acute on chronic pain in his big toe. Past history is significant for hypertension for which he takes Bendroflumethiazide 5mg daily. Examination reveals an erythematous, red hot metatarsophalangeal joint that has a knobbly appearance. X-ray shows punched out bony cysts. Which of the following would be the most appropriate long term management for this patient?
Your Answer: Stop Bendroflumethiazide and substitute a calcium antagonist
Explanation:The most likely diagnosis is chronic tophaceous gout, which is classically associated with chronic renal impairment or long term diuretic therapy. There is tophus formation due to urate crystal deposition in and around the joint. These tophi can also form in the bones and soft tissues. Renal manifestations with uric acid include nephrolithiasis and uric acid nephropathy. Whenever there is an acute on chronic attack of gout, the inciting cause must be established and in case of diuretic use, they should be immediately replaced with another medication. Allopurinol is never started during an acute episode. it is first allowed to settle before administration of allopurinol. Although dietary restriction must be observed in people with a propensity of gout, this scenario clearly presents diuretics as the cause.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 111
Incorrect
-
In the life cycle of plasmodium species:
Your Answer: Sporozoites enter the red blood cell
Correct Answer: Merozoites are released from the liver and enter the red blood cell
Explanation:Plasmodium is a genus of parasitic protozoa, many of which cause malaria in their hosts. The parasite always has two hosts in its life cycle: a Dipteran insect host and a vertebrate host. Sexual reproduction always occurs in the insect, making it the definitive host.The life-cycles of Plasmodium species involve several different stages both in the insect and the vertebrate host. These stages include sporozoites, which are injected by the insect vector into the vertebrate host’s blood. Sporozoites infect the host liver, giving rise to merozoites and (in some species) hypnozoites. These move into the blood where they infect red blood cells. In the red blood cells, the parasites can either form more merozoites to infect more red blood cells, or produce gametocytes which are taken up by insects which feed on the vertebrate host. In the insect host, gametocytes merge to sexually reproduce. After sexual reproduction, parasites grow into new sporozoites, which move to the insect’s salivary glands, from which they can infect a vertebrate host bitten by the insect.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 112
Correct
-
Tunica intima is made up of?
Your Answer: Endothelial cells
Explanation:Tunica intima is a single cell thick lining of endothelial cells that lines the inside of the blood vessels. It is the inner most layer of the blood vessel.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 113
Correct
-
The parietal cells of the stomach secrete which of the following?
Your Answer: Hydrochloric acid
Explanation:Parietal cells are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and in the body of the stomach.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 114
Incorrect
-
Empagliflozin was found to reduce the risk of cardiovascular deaths, non-fatal myocardial infarction and non-fatal stroke when added to standard treatment plans in patients with type 2 diabetes mellitus. This information was shared in 2015 by The New England Journal of Medicine and the results were expressed per 1000 patient years. In fact, empagliflozin had an event rate of 37.3/1000 patient years and placebo an event rate of 43.9/1000 patient years. How many patients who are at high cardiovascular risk need to be treated with empagliflozin to prevent a cardiovascular death, a non-fatal myocardial infarction or a non-fatal stroke?
Your Answer: 50
Correct Answer: 150
Explanation:The number needed to treat (NNT) is an absolute effect measure that has been used to assess beneficial and harmful effects of medical interventions. In this case the NNT can be calculated as follows: NNT = 1/ Absolute risk reduction (ARR). ARR=(Control event rate expressed per 1000 patient years) – (Experimental event rate expressed per 1000 patient years) = 43.9-37.3 = 6.6/1000 patient yearsNNT=(Patient years)/ARR = 1000/ 6.6 = 151.5. The closest to 151.5 is 150, thus it is the correct answer.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 115
Correct
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Question 116
Correct
-
A 30-year-old male is brought to the emergency department following his collapse in a night club. His friends who accompanied him admit that, of recent, he has been using increasing amounts of cocaine. Which among the following is commonly associated with cocaine overdose?
Your Answer: Metabolic acidosis
Explanation:Metabolic acidosis is associated with cocaine overdose. In overdose, cocaine leads to agitation, tachycardia, hypertension, sweating, hallucinations, and finally convulsions. Metabolic acidosis, hyperthermia, rhabdomyolysis, and ventricular arrhythmias also occur.Chronic use may be associated with premature coronary artery disease, dilated cardiomyopathy, and increased risk of cerebral haemorrhage.There are 3 stages for acute cocaine toxicity:Stage I: CNS symptoms of headache, vertigo, pseudo hallucinations, hyperthermia, hypertension. Stage II: increased deep tendon reflexes, tachypnoea, irregular breathing, hypertension.Stage III: Areflexia, coma, fixed and dilated pupils, hypotension, ventricular fibrillation, apnoea, and respiratory failure.Treatment:- Airway, breathing, and circulation to be secured. The patient’s fever should be managed, and one should rule out hypoglycaemia as a cause of the neuropsychiatric symptoms. – Cardiovascular toxicity and agitation are best-treated first-line with benzodiazepines to decrease CNS sympathetic outflow.- The mixed beta/alpha blocker labetalol is safe and effective for treating concomitant cocaine-induced hypertension and tachycardia.- Non-dihydropyridine calcium channels blockers such as diltiazem and verapamil have been shown to reduce hypertension reliably, but not tachycardia. – Dihydropyridine agents such as nifedipine should be avoided, as reflex tachycardia may occur. – The alpha-blocker phentolamine has been recommended but only treats alpha-mediated hypertension and not tachycardia.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 117
Incorrect
-
Absorption of fructose is via:
Your Answer: Secondary active transport
Correct Answer: Facilitated diffusion
Explanation:Dietary fructose may be ingested as a monosaccharide or as a disaccharide. Sucrose is hydrolysed by sucrase to produce equal amounts of glucose and fructose and in this form, is usually completely absorbed. Fructose is mostly absorbed in the small intestine through GLUT-5 transporter mediated facilitative diffusion. This is an energy independent process.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 118
Incorrect
-
The predominant receptors in the hearts conduction system are?
Your Answer: Β2
Correct Answer: Β1
Explanation:All of the components of the intrinsic conduction system contain autorhythmic cells that spontaneously depolarize. In the absence of extrinsic neural or hormonal influences, the SA node pacing rate would be about 100 beats per minute (bpm). The heart rate and cardiac output, however, must vary in response to the needs of the body’s cells for oxygen and nutrients under varying conditions. In order to respond rapidly to changing requirements of the body’s tissues, the heart rate and contractility are regulated by the autonomic nervous system (ANS), hormones, and other factors. The ANS has two interacting systems: the sympathetic and parasympathetic systems.
Sympathetic receptors: There are two types of adrenergic receptors: β and α. In the cardiovascular system there are β1, β2, α1, and α2 adrenergic receptors. β1 adrenergic receptors are expressed in the heart conduction system (in the SA node, AV node, and on atrial and ventricular cardiomyocytes). The activation of β1 receptors increases heart rate (via the SA node), and contractility.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 119
Incorrect
-
In which organelle is the intrinsic apoptotic pathway initiated?
Your Answer: Lysosome
Correct Answer: Mitochondria
Explanation:Apoptosis is a programmed form of cell death involving the degradation of cellular constituents by a group of cysteine proteases called caspases. The caspases can be activated through either the intrinsic (mitochondrial mediated) or extrinsic (death receptor mediated) apoptotic pathways.
The intrinsic apoptotic pathway, also known as the mitochondrial pathway, is primarily initiated within the mitochondria. This pathway is activated in response to various internal stimuli, such as DNA damage, oxidative stress, and other cellular stresses.
When the intrinsic pathway is triggered, several events occur in the mitochondria:
- Release of cytochrome c: Cytochrome c is released from the mitochondrial intermembrane space into the cytoplasm.
- Formation of the apoptosome: Cytochrome c in the cytoplasm binds to apoptotic protease activating factor-1 (Apaf-1) and procaspase-9, forming a complex known as the apoptosome.
- Activation of caspase-9: The apoptosome activates caspase-9, an initiator caspase.
- Caspase cascade: Activated caspase-9 then activates executioner caspases, such as caspase-3, leading to the execution phase of apoptosis, which results in the orderly dismantling of the cell.
The mitochondria play a crucial role in this pathway by regulating the release of pro-apoptotic factors that are essential for the activation of downstream apoptotic processes.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 120
Incorrect
-
Which of the following drug can cause galactorrhoea?
Your Answer: Lisinopril
Correct Answer: Metoclopramide
Explanation:Metoclopramide causes extrapyramidal effects (especially in children and young adults), hyperprolactinaemia, and occasionally tardive dyskinesia on prolonged administration. Also reported are drowsiness, restlessness, diarrhoea, depression, neuroleptic malignant syndrome, rashes, pruritus, oedema.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 121
Correct
-
The following products of the vascular endothelium produce vasodilation except:
Your Answer: Endothelin
Explanation:Endothelin: This is incorrect in the context of vasodilation. Endothelin is actually a potent vasoconstrictor produced by the endothelium, leading to the narrowing of blood vessels and increased blood pressure.
Nitrous oxide (Nitric oxide): This is correct for vasodilation. Nitric oxide is a powerful vasodilator produced by the endothelium, which helps relax and widen blood vessels.
Prostacyclin: This is correct for vasodilation. Prostacyclin (PGI2) is a vasodilator and inhibits platelet aggregation, helping to maintain blood flow and reduce clot formation.
Endothelial-derived hyperpolarizing factor (EDHF): This is correct for vasodilation. EDHF causes vasodilation by hyperpolarizing the smooth muscle cells of blood vessels.
Vascular endothelial growth factor (VEGF): This is correct for vasodilation. VEGF primarily promotes the growth of new blood vessels but also has vasodilatory effects through nitric oxide production.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 122
Incorrect
-
With regard to carbohydrate absorption, which sodium-dependent glucose transporter (SGLT) is responsible for the uptake of dietary glucose from the gut?
Your Answer: SGLT 2
Correct Answer: SGLT 1
Explanation:SGLT- Sodium-dependent glucose cotransporter or sodium-glucose linked transporter are family of proteins of different types. SGLT1 transporter is found in the intestinal mucosa of the small intestine.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 123
Correct
-
Which of the toxin secretion pathways in the cell membrane of gram– bacteria delivers the toxin extracellular in a 2 stage process to the host?
Your Answer: II
Explanation:Gram negative bacteria contain two membranes and there are about six specialized secretion systems. The secreted proteins play a key role in pathogenesis. Type II secretion systems (T2SS) are conserved in most Gram-negative bacteria, where they transport proteins from the periplasm into the extracellular environment. Because the T2SS channel is only found in the outer membrane, proteins secreted through this apparatus must first be delivered to the periplasm via the Sec or Tat secretion pathways and then to the extracellular environment making it a two-stage process.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 124
Correct
-
VIP, GIP and somatostatin play an inhibitory role in gastric acid secretion by inactivating?
Your Answer: G cells
Explanation:Gastrin is secreted from the G cells. VIP, GIP and somatostatin all inhibit acid production by inhibiting the G cells.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 125
Correct
-
Which of the following foods contain Vitamin B 12?
Your Answer: Liver, meat
Explanation:No fungi, plants, nor animals (including humans) are capable of producing vitamin B12. Only bacteria and archaea have the enzymes needed for its synthesis. Proved food sources of B12 are animal products (meat, fish, dairy products).
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This question is part of the following fields:
- Haematology
- Medicine
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Question 126
Correct
-
All of the following are associated with yellow nail syndrome except:
Your Answer: Cardiomegaly
Explanation:Yellow nail syndrome is a very rare medical syndrome that includes pleural effusions, lymphedema (due to under development of the lymphatic vessels) and yellow dystrophic nails. Approximately 40% will also have bronchiectasis. It is also associated with chronic sinusitis and persistent coughing and it usually affects adults.
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 127
Correct
-
Which of the following is an incorrect statement regarding the structure of DNA?
Your Answer: The two strands of DNA are held together by cysteine bonds.
Explanation:The two strands of DNA are held together by hydrogen bonds formed between the nucleotide bases.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 128
Correct
-
With regards to the function of the p53 protein produced by the p53 gene, which of the following statements is incorrect?
Your Answer: It permits repair of mutations and other defects in RNA
Explanation:The p53 protein is a crucial tumor suppressor and plays several key roles in maintaining cellular integrity:
- Nuclear transcription factor: p53 is a nuclear transcription factor that regulates the expression of various genes involved in cell cycle control, DNA repair, apoptosis, and senescence.
- DNA repair: p53 permits repair of mutations and other defects in DNA (not RNA). It activates the transcription of genes involved in DNA repair mechanisms, allowing the cell to correct errors before proceeding with the cell cycle.
- Cell cycle regulation: p53 can induce the expression of p21, a protein that inhibits cyclin-dependent kinases, thereby halting the cell cycle at the G1/S checkpoint to allow time for DNA repair or to trigger apoptosis if the damage is irreparable. Mutations in p53 may fail to halt the cell cycle, allowing mutations to persist and potentially leading to cancer.
- Apoptosis: If DNA damage is extensive and cannot be repaired, p53 triggers apoptosis to prevent the propagation of damaged cells.
- Suppression of proto-oncogenes: p53 indirectly contributes to the suppression of proto-oncogenes by preventing the proliferation of cells with damaged DNA, thereby reducing the risk of oncogenic transformation.
Given these functions, the statement that p53 “permits repair of mutations and other defects in RNA” is incorrect, as p53 is primarily involved in the repair of DNA, not RNA.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 129
Correct
-
The spinal cord receive its blood supply from the following arteries except:
Your Answer: Lateral spinal artery
Explanation:The spinal cord (SC) is supplied by the single anterior spinal artery which supplies the anterior two thirds of the SC and paired posterior spinal arteries supplying the posterior one third. Anastomoses between the spinal arteries supply the lateral column. These arteries originate near the cervico-occipital junction and therefore have a smaller calibre and often discontinue. Thus, they require reinforcement by segmental/radicular arteries which are branches of the ascending cervical artery, deep cervical artery, intercostal arteries, lumbar arteries and lateral sacral arteries
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This question is part of the following fields:
- Medicine
- Neurology
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Question 130
Correct
-
The following are synthesized in the liver EXCEPT?
Your Answer: Cholecystokinin
Explanation:The liver is responsible for the mainstay of protein metabolism, synthesis as well as degradation. It is also responsible for a large part of amino acid synthesis. The liver plays a role in the production of clotting factors as well as red blood cell production. Some of the proteins synthesized by the liver include coagulation factors I (fibrinogen), II (prothrombin), V, VII, VIII, IX, X, XI, XIII, as well as protein C, protein S and antithrombin. The liver is a major site of production for thrombopoietin, a glycoprotein hormone that regulates the production of platelets by the bone marrow. The liver also produces albumin, the most abundant protein in blood serum and angiotensinogen. Cholecystokinin, previously called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 131
Correct
-
The rate of depolarisation of the sinus node membrane potential is modulated by all the following except:
Your Answer: Cardiac output
Explanation:Cardiac output has no effect on the depolarization of the pacemaker potential of the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 132
Correct
-
In the normal adult, haematopoiesis is present
Your Answer: Axial skeleton and proximal ends of long bones
Explanation:In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia. In adults, it occurs mainly in the pelvis, cranium, vertebrae, and sternum.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 133
Correct
-
What are the diagnostic criteria for an ST segment elevation type of acute myocardial infarction?
Your Answer: 1 mm ST elevation in 2 limb leads
Explanation:The current guidelines for the ECG diagnosis of the ST segment elevation type of acute myocardial infarction require at least 1 mm (0.1 mV) of ST segment elevation in the limb leads, and at least 2 mm elevation in the precordial leads. These elevations must be present in anatomically contiguous leads. (I, aVL, V5, V6 correspond to the lateral wall; V3-V4 correspond to the anterior wall ; V1-V2 correspond to the septal wall; II, III, aVF correspond to the inferior wall.)
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 134
Correct
-
The following determines the strength of contraction
Your Answer: Plateau phase
Explanation:The plateau phase which follows is unique to myocytes and results from a small, but sustained inward calcium current through L-type calcium channels lasting 200-400 ms. This calcium influx is caused by a combined increase in permeability of the cell and especially the sarcolemmal membranes to calcium. This plateau (or refractory) phase in myocyte action potential prevents early reactivation of the myocytes and directly determines the strength of contraction
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 135
Incorrect
-
Which of the following limits the duration of inspiration and increases respiratory rate?
Your Answer: Apneustic centre
Correct Answer: Pneumotaxic centre
Explanation:The mechanism of control of ventilation is an interplay of multiple regions in the brain. The medullary respiratory centre sets the basic rhythm of breathing and the pons modifies the output of the medullary centres. There are two pontine centres: apneustic and pneumotaxic.
The pnuemotaxic centre controls inspiratory time. Increased signals to this area increases respiratory rate. The dorsal respiratory group (DRG) integrates input from the stretch receptors and the chemoreceptors in the periphery and is composed mainly of inspiratory neurons. The DRG controls the basic rhythm of breathing by triggering inspiratory impulses. The ventral respiratory group (VRG) generates breathing rhythm and integrates data coming into the medulla and contains both inspiratory and expiratory neurons. They are primarily active in exercise and stress.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 136
Correct
-
Which of the following conditions is NOT X-linked recessive?
Your Answer: Cystic fibrosis
Explanation:Cystic fibrosis is a autosomal recessive disease with an incidence of about 1 in 2500 live births. The most common mutation occurs in the long arm of chromosome 7 which codes for the chloride channel (cystic fibrosis transmembrane conductance regulator) gene.
To have CF, a child must inherit two abnormal genes—one from each parent. The recessive CF gene can occur in both boys and girls because it is located on non-sex-linked chromosomes called autosomal chromosomes.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 137
Correct
-
On which chromosome is the gene for insulin located?
Your Answer: Chromosome 11
Explanation:Humans have 23 pairs of chromosomes, and usually, two pairs of copies of chromosome 11. It is one of the most complex, gene-rich chromosomes in the human genome, and it is associated with a number of diseases. Studies have shown they the human insulin gene is located on the short arm of chromosome 11.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 138
Correct
-
During exercise, a man consumes 2L O2/min, his arterial 02 content is 190 ml/l and the 02 content of his mixed venous blood is 130ml/l. His cardiac output is approximately:
Your Answer: 33l/min
Explanation:In Fick’s original method, the following variables are measured:VO2, oxygen consumption in ml of pure gaseous oxygen per minute. This may be measured using a spirometer within a closed rebreathing circuit incorporating a CO2 absorberCa, the oxygen concentration of blood taken from the pulmonary vein (representing oxygenated blood)Cv, the oxygen concentration of blood from an intravenous cannula (representing deoxygenated blood)From these values, we know that:VO2 = (CO x Ca) – (CO x Cv)where CO = Cardiac Output, Ca = Oxygen concentration of arterial blood and Cv = Oxygen concentration of mixed venous blood.This allows us to sayCO = VO2/{Ca – Cv}and hence calculate cardiac output.Therefore CO = 2/(0.190-0.130) = 33l/minNote that (Ca – Cv) is also known as the arteriovenous oxygen difference.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 139
Incorrect
-
During strenuous exercise the following arterial change can take place in a fit athlete:
Your Answer: Both oxygen and carbon dioxide will change
Correct Answer: No change takes place
Explanation:The changes which occur in arterial pH, PO2 and PCO2 values during exercise are usually small. Arterial PO2 often rises slightly because of hyperventilation although it may eventually fall at high work rates. During vigorous exercise, when sufficient oxygen for flux through the Krebs cycle is not available, the increased reliance on glycolysis results in increased accumulation of lactic acid, which initially leads to an increase in PaCO2 . However, this is counteracted by the stimulation of ventilation and as a result PaCO2 is decreased. This provides some respiratory compensation for further lactic acid production and prevents a decline in blood pH, which remains nearly constant during moderate exercise.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 140
Correct
-
A 28 year old woman presents with painful genital ulceration. She reports that these attacks have been recurrent over the past 4 years. She has been treated previously with oral acyclovir but this has had little effect on the duration of her symptoms. Over the past year, she has noticed almost weekly attacks of mouth ulcers that heal slowly. Past medical history is significant for treatment of thrombophlebitis two years ago. Which of the following is the most likely diagnosis?
Your Answer: Behcet's syndrome
Explanation:Behçet disease is a rare vasculitic disorder that is characterized by a triple-symptom complex of recurrent oral aphthous ulcers, genital ulcers, and uveitis. The systemic manifestations can be variable. Ocular disease has the greatest morbidity, followed by vascular disease generally from active vasculitis. Cutaneous manifestations can occur in up 75% of patients with Behcet disease and can range from acneiform lesions, to nodules and erythema nodosum. GI manifestations can be severe. Differentiating Behçet disease from active inflammatory bowel disease can be clinically difficult. Herpes would have ideally responded to acyclovir. Sarcoidosis does not have genital and oral ulcerations.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 141
Correct
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Question 142
Incorrect
-
Which of the following is the most common clinical feature of carbon monoxide poisoning?
Your Answer: Cherry red skin
Correct Answer: Headache
Explanation:Carbon monoxide (CO) poisoning:It is considered as the great imitator of other diseases as the patients present with a myriad of symptoms. The carbon monoxide diffuses rapidly across the pulmonary capillary membrane binding to the haem molecule with a very high affinity (240 times that of oxygen) forming carboxy-haemoglobin (COHb). Non-smokers have a baseline COHb of ,3% while smokers have a baseline COHb of 10-15%.Clinical features of carbon monoxide toxicity:Headache: 90% of cases (most common clinical feature)Nausea and vomiting: 50%Vertigo: 50%Confusion: 30%Subjective weakness: 20%Severe toxicity: ‘pink’ skin and mucosa, hyperpyrexia, arrhythmias, extrapyramidal features, coma, deathCherry red skin is a sign of severe toxicity and is usually a post-mortem finding.Management• 100% oxygen• Hyperbaric oxygen therapy (HBOT)The use of Hyperbaric oxygen therapy (HBOT) for treatment mild to moderate CO poisoning is not routine.The selection criteria for HBOT in cases of CO poisoning include:• COHb levels > 20-25%• COHb levels > 20% in pregnant patient • Loss of consciousness• Severe metabolic acidosis (pH <7.1)• Evidence of end-organ ischemia (e.g., ECG changes, chest pain, or altered mental status)
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 143
Correct
-
A 52-year-old man has squamous-cell carcinoma of his lower lip. Which of the following is most likely to be a feature of this type of carcinoma?
Your Answer: It is capable of metastasising via the lymphatics
Explanation:Squamous-cell skin cancer usually presents as a hard lump with a scaly top but can also form an ulcer. Onset is often over months and it is more likely to spread to distant areas than basal cell cancer vie the lymphatics. The greatest risk factor is high total exposure to ultraviolet radiation from the Sun. Other risks include prior scars, chronic wounds, actinic keratosis, lighter skin, Bowen’s disease, arsenic exposure, radiation therapy, poor immune system function, previous basal cell carcinoma, and HPV infection. While prognosis is usually good, if distant spread occurs five-year survival is ,34%
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This question is part of the following fields:
- Dermatology
- Medicine
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Question 144
Correct
-
Which of the flowing plasma proteins has the greatest affinity for T4?
Your Answer: Thyroxin-binding globulin
Explanation:There are three principal plasma thyroid hormone-binding proteins, thyroxine-binding globulin (TBG), transthyretin (TTR), and albumin. TBG is synthesized in the liver and due to its relatively high affinity for iodothyronines, binds and carries approximately 70–75% of circulating T4 and T3.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 145
Correct
-
Protozoa is part of which pathogenic group?
Your Answer: Eukaryotes
Explanation:Protozoa are a diverse group of unicellular eukaryotic organisms. Historically, protozoa were defined as single-celled organisms with animal-like behaviours, such as motility and predation.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 146
Correct
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An 80 year old female, previously diagnosed with polymyalgia rheumatica 18 months back, presents to the outpatient clinic with bilateral shoulder stiffness and generalized myalgia. The ESR was found to be 60mm/1st hour at the time of presentation. Prednisolone therapy was initiated at a daily dose of 15 mg along with Calcium and Vitamin supplementation. She reported resolution of her symptoms in one week. However the symptoms relapsed when the prednisolone dose was reduced below the current dose of 12.5 mg daily. How should she be ideally managed?
Your Answer: Continue the current dose of prednisolone and start methotrexate
Explanation:Polymyalgia rheumatica, a syndrome characterized by proximal muscle pain and stiffness in older persons, generally is treated with prednisone. Dosages of 15 to 25 mg of prednisone per day can reduce inflammation considerably, although many patients relapse when therapy is tapered. Long-term (18 to 36 months) steroid treatment has been recommended by several studies, but this can result in multiple side effects, including osteoporosis, hypertension, cataracts, and hyperglycaemia. Methotrexate has been used to reduce inflammation in rheumatoid arthritis, systemic vasculitis, and giant cell arteritis, and in some studies has been combined with prednisone to treat polymyalgia rheumatica, decreasing the duration of treatment.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 147
Correct
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Which of the following is the correct way to calculate the anion gap?
Your Answer: (Na + K) – (HCO3 + Cl)
Explanation:The anion gap is the difference between the measured cations (positively charged ions) and the measured anions (negatively charged ions) in serum, plasma, or urine. The magnitude of this difference in the serum is often calculated in medicine when attempting to identify the cause of metabolic acidosis. Anion Gap = ([Na+] + [K+]) − ([Cl−] + [HCO−3])
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This question is part of the following fields:
- Medicine
- Renal
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Question 148
Correct
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The following are examples of the functions of the vascular endothelium except:
Your Answer: Tumour suppression
Explanation:Vascular endothelium has many important functions including regulation of vascular tone, molecular exchange between blood and tissue compartments, hemostasis and signaling for the immune regulation and inflammation. Depending on specific tissue needs and local stresses, endothelial cells are capable of evoking either antithrombotic or prothrombotic events. Tumor suppression is related to genes, or anti-oncogenes, that regulate a cell during cell division and replication.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 149
Correct
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Role of bile salts in digestion of fats include
Your Answer: Reduce surface tension, emulsification and transportation
Explanation:Bile acts to some extent as a surfactant reducing surface tension, helping to emulsify the lipids in food. Bile salt anions are hydrophilic on one side and hydrophobic on the other side; consequently, they tend to aggregate around droplets of lipids (triglycerides and phospholipids) to form micelles, with the hydrophobic sides towards the fat and hydrophilic sides facing outwards. The hydrophilic sides are negatively charged, and this charge prevents fat droplets coated with bile from re-aggregating into larger fat particles.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 150
Incorrect
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Which lipoprotein is responsible for lowering of plasma lipids?
Your Answer: LDL
Correct Answer: HDL
Explanation:High-density lipoproteins (HDL) are one of the five major groups of lipoproteins. Lipoproteins are complex particles composed of multiple proteins which transport all fat molecules (lipids) around the body within the water outside cells. Unlike the larger lipoprotein particles which deliver fat molecules to cells, HDL particles remove fat molecules from cells.
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This question is part of the following fields:
- Medicine
- Metabolism
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