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Question 1
Correct
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A deficiency in Cyanocobalamin leads to which clinical deficiency syndrome?
Your Answer: Pernicious anaemia
Explanation:The main syndrome of vitamin B12 deficiency is pernicious anaemia. It is characterized by a triad of symptoms:Megaloblastic anaemiaGastrointestinal symptoms &Neurological symptoms
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 2
Correct
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Which of the following forms one of the characteristic and functional cells making up the anterior pituitary gland?
Your Answer: Corticotrope
Explanation:The anterior pituitary, also known as adenohypophysis or pars anterior contains the following types of cells: – acidophil cells: somatotroph cells, which produce growth hormone; and lactotrophs, which produce prolactin- basophil cells: corticotropes, which produce adrenocorticotropic hormone; thyrotropes, which produce thyroid stimulating hormone; and – gonadotrophs, which produce luteinizing hormone and follicle stimulating hormone.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 3
Correct
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Changes in cadherin expression are associated with
Your Answer: Tumour metastatic potential
Explanation:Cadherins play a role in maintaining cell and tissue structure, and in cellular movement. The E-cadherin–catenin complex plays a key role in cellular adhesion; loss of this function has been associated with greater tumour metastasis.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 4
Correct
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The lower oesophageal sphincter is under neural control. Which of the following causes contraction of the intrinsic sphincter?
Your Answer: Acetylcholine
Explanation:The lower oesophageal sphincter (LOS) is a specific region of the oesophageal circular smooth muscle. It allows the passage of a food bolus to the stomach and prevents the reflux of gastric contents into the oesophagus. The tone of the LOS is myogenic in origin and depends on smooth muscle properties that lead to the opening of Ca2+ channels but can also be modulated by enteric motor neurons, the parasympathetic and sympathetic extrinsic nervous system and several neurohumoral substances. Nitric oxide causes LOS relaxation. Acetylcholine and tachykinins are involved in the LOS contraction.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 5
Incorrect
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Which of the following normally has a slow depolarizing “prepotential”?
Your Answer: Ventricular muscle cells
Correct Answer: Sinoatrial node
Explanation:There are 2 main types of action potentials (AP) in the heart, the slow response and the fast response:The slow response is initiated by the slow calcium-sodium channels, found in the SA node (which is the natural pacemaker of the heart) and the conduction fibers of the AV node.The fast response occurs in the atrial and ventricles muscle cells and the purkinje fibers.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 6
Incorrect
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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 7
Correct
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Which protein in the HIV genome is responsible for binding to the host CD4 cells?
Your Answer: gp120
Explanation:HIV can infect a variety of immune cells such as CD4+ T cells, macrophages, and microglial cells. HIV-1 entry to macrophages and CD4+ T cells is mediated through interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells and also with chemokine coreceptors.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 8
Correct
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What is the primary cause of ketoacidosis in Type 1 diabetes?
Your Answer: Lipolysis
Explanation:in type 1 diabetics the lack of insulin in the bloodstream prevents glucose absorption, thereby inhibiting the production of oxaloacetate (a crucial precursor to the β-oxidation of fatty acids) through reduced levels of pyruvate (a by-product of glycolysis), and can cause unchecked ketone body production (through fatty acid metabolism or lipolysis) potentially leading to dangerous glucose and ketone levels in the blood.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 9
Correct
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Osteopetrosis occurs as a result of a defect in:
Your Answer: Osteoclast function
Explanation:It is a metabolic bone disease caused by defective osteoclastic resorption of immature bone. Osteopetrosis is also known as marble bone disease. Osteoclasts are unable to adequately acidify bone matrix. Impaired bone resorption leads to overly dense bone that is more likely to fracture. It is usually treated with bone marrow transplant and high dose calcitriol.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 10
Correct
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Excitation-contraction coupling in cardiac muscle involves all of the following except:
Your Answer: Binding of Ca2+ to calmodulin
Explanation:In the excitation contraction coupling model, an action potential is transmitted to the fibrils of a fiber through the T tubule system. It triggers the release of Ca 2+ from the terminal cisterns. Depolarization of the T tubules activates the sarcoplasmic reticulum through the dihydropyridine receptors. These are voltage gates calcium channels. Calcium binds to calmodulin during contraction of the smooth muscle and not the cardiac muscles.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 11
Correct
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In most somatic cells telomeres progressively shorten as:
Your Answer: The cell divides
Explanation:Telomerase activity is seen in germ cells and is absent in somatic cells. A somatic cell is any biological cell forming the body of an organism, other than a gamete, germ cell, gametocyte or undifferentiated stem cell. i.e. liver cells. 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 12
Incorrect
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Concerning protein digestion:
Your Answer: Human pepsinogens can be divided into four immunochemically distinct groups
Correct Answer: Most protein digestion occurs in the duodenum
Explanation:Human pepsinogens can be divided into two immunochemically distinct groups: Pepsinogen I (PG I) and Pepsinogen II (PGII). PG I is secreted mainly by chief cells in the fundic mucosa whereas PGII is secreted by the pyloric glands and the proximal duodenal mucosa. Maximal acid secretion correlates with PG I. Most protein digestion occurs in the duodenum/jejunum. Pepsin functions best in an acidic environment and specifically at a pH of 1.5 to 3.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 13
Incorrect
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A 32 year old woman presents with a painful elbow which she has been feeling for the past two weeks. Which of the following will be consistent with a diagnosis of tennis elbow?
Your Answer: Pain on pressure over the medial epicondyle
Correct Answer: Pain on wrist extension against resistance
Explanation:Lateral epicondylitis (tennis elbow) is an overuse injury of the hand and finger extensor tendons that originate in the lateral humeral epicondyle that occurs following repeated or excessive pronation/supination and extension of the wrist (e.g., in racquet sports). Clinical features include pain and tenderness over the lateral epicondyle and along extensor muscles and thickening of the tendons. The examiner holds the patient’s hand with the thumb placed over the lateral epicondyle – The patient makes a fist, supinates the forearm, deviates radially, and extends the fist against the examiner’s resistance which will result in pain over the lateral epicondyle. Conservative treatment includes rest, physiotherapy and orthotic braces. If this fails corticosteroids and lidocaine injections are employed. Surgery is indicated in patients with persistent symptoms despite 6 months of conservative treatment. Excision of abnormal tendon tissue; longitudinal incisions (tenotomies) in scarred and fibrotic areas to promote healing.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 14
Incorrect
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Where does one find the thyroid receptors?
Your Answer: Cell membrane
Correct Answer: Cell nucleus
Explanation:Unlike many of the steroid receptors, inactive receptors for T3 are located in the nucleus. T4 is first converted into T3 within the cytoplasm of the cell, T3 then enters the nucleus and binds to its receptor. The hormone-receptor complex can now bind to DNA and activate specific genes.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 15
Incorrect
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What is the isolated effect of B2 stimulation on the coronaries?
Your Answer: Vasoconstriction
Correct Answer: Vasodilatation
Explanation:Norepinephrine and epinephrine are agonists for all adrenergic receptor subtypes, although with varying affinities. Based on their physiology and pharmacology, adrenergic receptors have been divided into two principal types: alpha and beta. These types have been further differentiated into alpha-1, alpha-2, b1, and b2 receptors.
Alpha-1 Receptors are located on postsynaptic cells in smooth muscle and elicit vasoconstriction.
Alpha-2 receptors are localized on presynaptic membranes of postganglionic nerve terminals that synthesize norepinephrine. When activated by catecholamines, alpha-2 receptors act as negative feedback controllers, inhibiting further norepinephrine release.
Activation of myocardial b1 receptors stimulates the rate and strength of cardiac contraction, and consequently increases cardiac output. b1 Receptor activation also stimulates renin release from the kidney. Another class of antihypertensive agents acts by inhibiting b1 receptors.
Activation of b2 receptors by epinephrine relaxes vascular smooth muscle and results in vasodilation.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 16
Incorrect
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What is the average life span of neutrophils?
Your Answer: 7 months
Correct Answer: 24 hours
Explanation:The average lifespan of inactivated human neutrophils in the circulation has been reported by different approaches to be between 5 and 90 hours.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 17
Incorrect
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The transport of the di- and tri-peptides into enterocytes is by:
Your Answer: Na+ dependent peptide transporter 1
Correct Answer: H+ dependent peptide transporter 1
Explanation:Peptides longer that four amino acids are not absorbed. There is abundant absorption of di and tri peptidases in the small intestine. They are absorbed into the epithelial cell of the small intestine via a transporter called Peptide Transporter 1 by co transport with H+ ions.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 18
Correct
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Which of the following statements is false regarding the bioavailability of a drug?
Your Answer: The bioavailability of a drug given orally is often affected by the degree of renal elimination
Explanation:Renal elimination of a drug has no role in altering the bioavailability of a drug.The bioavailability of a drug is the proportion of the drug which reaches systemic circulation. Mathematically, bioavailability is the AUCoral/AUCiv x 100%, where AUC = area under the concentration-time curve following a single (oral or iv) dose. Other options are true:By definition, the bioavailability of a drug given intravenously is 100%.Drugs given orally that undergo high pre-systemic (first-pass) metabolism in the liver or gut wall have a low bioavailability e.g. lidocaine. Bioavailability is also affected by the degree of absorption from the gut and this can change depending on gut motility and administration of other drugs.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 19
Correct
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Question 20
Correct
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Which of the following stimuli increase growth hormone secretion?
Your Answer: Ghrelin
Explanation:Ghrelin is a hormone which serves as an endogenous ligand for the growth hormone secretagogue receptor. It acts on the pituitary and the hypothalamus by affecting the vagus nerve. It acts on the somatotrophs of the anterior pituitary, GHRH-secreting neurons, and on GHIH-secreting neurons in the hypothalamus, causing a time-dependent and pulsatile stimulation over the secretion of growth hormone.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 21
Incorrect
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Which one of the following have not been shown to improve mortality in patients with chronic heart failure?
Your Answer: Beta-blockers
Correct 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 22
Incorrect
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Telomerase is active in all of the following cells, except:
Your Answer: Stem cells
Correct Answer: Certain liver cells
Explanation:Telomerase is an enzyme that adds repetitive nucleotide sequences to the ends of chromosomes (telomeres), preventing their shortening during cell division. Telomerase activity is crucial for cells that divide frequently and need to maintain their telomere length for continued proliferation. These include:
- Stem cells: They have high telomerase activity to maintain their long-term proliferative capacity.
- Germ cells: These cells also have active telomerase to ensure the stability of genetic material across generations.
- Certain white blood cells: Some immune cells, particularly those that need to proliferate in response to infection, show telomerase activity.
- Certain cancer cells: Many cancer cells reactivate telomerase, which contributes to their uncontrolled growth and immortality.
However, most somatic cells, including certain liver cells, do not exhibit significant telomerase activity. While some liver cells might show low levels of telomerase activity during regeneration, it is not generally active in normal, differentiated liver cells.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 23
Incorrect
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Which one of the following is a risk factor for torsade de pointes?
Your Answer: Hyperkalaemia
Correct Answer: Hypothermia
Explanation:The following is a list of factors associated with an increased tendency toward torsades de pointes:- Hypokalaemia (low blood potassium)- Hypomagnesemia (low blood magnesium)- Hypocalcaemia (low blood calcium)- Bradycardia (slow heartbeat)- Heart failure- Left ventricular hypertrophy- Hypothermia- Subarachnoid haemorrhage- Hypothyroidism
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 24
Correct
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Which of the following is the most common clinical feature of carbon monoxide poisoning?
Your 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 25
Correct
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The process whereby bacterial products interact with plasma factors and cells to produce agents that attract neutrophils to an infected area is called:
Your Answer: Chemotaxis
Explanation:During an inflammatory process many cytokines are produced that act as chemokines to attract neutrophils to the site of inflammation. These include bacterial products, IL-8, C5a and LTB4.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 26
Incorrect
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Cholesterol is synthesized in all of these organs EXCEPT?
Your Answer: Skin
Correct Answer: Stomach
Explanation:The liver primarily synthesizes about 20-25% of the total daily cholesterol. Cholesterol is also synthesized to smaller extents in the adrenal glands, reproductive organs (as cholesterol is the precursor of sex hormones), skin and is also produced in the intestines.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 27
Correct
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Which of the following cells will degranulate and release histamine when binding to IgE?
Your Answer: Basophils
Explanation:Basophils have protein receptors on their cell surface that bind IgE, an immunoglobulin involved in microparasite defence and allergy. When activated, basophils degranulate to release histamine, proteoglycans (e.g. heparin and chondroitin), and proteolytic enzymes (e.g. elastase and lysophospholipase).
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This question is part of the following fields:
- Haematology
- Medicine
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Question 28
Incorrect
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Which enzyme is responsible for the conversion of testosterone to dihydrotestosterone?
Your Answer: 21β-hydroxylase
Correct Answer: 5α-reductase
Explanation:The enzyme 5α-reductase synthesizes DHT from testosterone in the prostate, testes, hair follicles, and adrenal glands. This enzyme reduces the 4,5 double-bond of the testosterone. Relative to testosterone, DHT is much more potent as an agonist of the androgen receptor.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 29
Incorrect
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Which intercellular connections are responsible for fastening the cells to one another?
Your Answer: Connexons & tight junctions
Correct 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 30
Correct
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In the cardiac cycle, all of the following are true except:
Your Answer: Mitral valve is closed by contraction of papillary muscles
Explanation:Mitral valve is closed by contraction of papillary muscles: This statement is incorrect. The mitral valve closes due to the pressure difference between the left ventricle and the left atrium at the onset of ventricular systole. The papillary muscles contract to prevent prolapse of the valve into the atrium but do not cause the valve to close.
The left ventricular volume is maximal at the end of atrial systole: This statement is true. At the end of atrial systole, the atria have pushed the remaining blood into the ventricles, making the ventricular volume maximal (end-diastolic volume).
The left ventricular pressure is maximal just before the aortic valve opens: This statement is true. Left ventricular pressure peaks just before the aortic valve opens, as the ventricle contracts to overcome the pressure in the aorta.
The ejection fraction is about 55%: This statement is true. The ejection fraction, which is the percentage of blood ejected from the ventricles with each contraction, is typically around 55%.
The ‘a’ wave is due to atrial systole: This statement is true. The ‘a’ wave on the venous pressure curve corresponds to atrial systole, reflecting the increased pressure from atrial contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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SESSION STATS - PERFORMANCE PER SPECIALTY
