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Question 1
Incorrect
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Which statement is correct?
Your Answer: Mitochondrial DNA has a double helix structure and also has a critical role in apoptosis.
Correct Answer: MtDNA principally encodes for proteins that are involved in oxidative phosphorylation for the production of ATP in the cell.
Explanation:Mitochondria have no nucleus instead they contain their own free floating circular genome (MtDNA), which encodes 13 different subunits of proteins involved in oxidative phosphorylation. The remainder of the mitochondrial proteins are nuclear encoded, synthesized in the cytoplasm, and transported into the mitochondria.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 2
Correct
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Which one of the following is able to move across cell membranes by passive diffusion?
Your Answer: CO2
Explanation:The cell membrane is permeable to water molecules and a few other small, uncharged, molecules like oxygen (O2) and carbon dioxide (CO2). Larger molecules like glucose or charged ions are unable to cross passively.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 3
Incorrect
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Activation of baroreceptor reflex involves:
Your Answer: Excitation of neurons in the rostral ventrolateral medulla (RVLM)
Correct Answer: Short term regulation of systemic blood pressure
Explanation:Baroreceptors are found in the heart and the blood vessels. They are the carotid sinus and the aortic arch receptors and respond to the minute to minute change in the blood pressure i.e. a change in the pulsatile pressure and not to a change in the mean arterial pressure. If the pulse pressure decreases, the rate of firing of the receptors decreases, stimulating an increase in the heart rate and blood pressure. Mechanisms that regulate the long term blood pressure control include the renin-angiotensin-aldosterone mechanism.
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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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Calcium is transported over the brush border in the gut, via which transporter / channel?
Your Answer: TRPV 6
Explanation:Transient Receptor Potential Vanilloid 6 or TRPV 6 is a calcium channel located in the cell membrane which is present in a variety of organs, including small intestine, oesophagus, stomach, colon, placenta, kidney, and uterus. In the intestine, it is located in the apical brush-border membrane of the enterocyte, regulating the entry of calcium into the cell.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 5
Correct
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A 49 year old female presents to the clinic complaining of pain in her left elbow that is localized to the left lateral epicondyle. She has spent the weekend painting her house. A diagnosis of lateral epicondylitis is suspected. The pain would characteristically worsen on which of the following movements?
Your Answer: Resisted wrist extension with the elbow extended
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, 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 results 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 6
Correct
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Question 7
Correct
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Question 8
Incorrect
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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: Third generation oral contraceptive pill use
Correct 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 9
Incorrect
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What is the function of the BK channel on the vascular smooth muscle membrane?
Your Answer: Promotes smooth muscle contraction opening the voltage gated Ca2+ channel
Correct Answer: Massive K+ efflux, increasing membrane potential, and shutting off the voltage gated Ca2+ channel
Explanation:BK channels, also known as large-conductance calcium-activated potassium channels, play a critical role in regulating vascular smooth muscle tone. When BK channels open, they allow a large efflux of potassium ions (K+) out of the cell. This efflux of K+ causes the membrane potential to become more negative (hyperpolarization), which in turn leads to the closure of voltage-gated calcium channels. The closure of these calcium channels reduces the influx of calcium ions (Ca2+) into the smooth muscle cells, resulting in decreased intracellular calcium levels and subsequent relaxation of the smooth muscle.
Thus, BK channels promote smooth muscle relaxation by hyperpolarizing the membrane and reducing the activity of voltage-gated Ca2+ channels.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Incorrect
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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: Brain tumour
Correct 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 11
Correct
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Which factor produced by the endothelium is responsible for the regulation of vascular cell growth?
Your Answer: Vascular endothelial growth factor (VEGF)
Explanation:VEGF is produced by the endothelial cells and is the major growth factor responsible for causing vasculogenesis. Some isoforms of this growth factor also have a prominent role in formation of lymphatic vessels.
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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 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 13
Correct
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Which of the following increase insulin secretion?
Your Answer: Sulfonylureas
Explanation:Sulfonylureas are a type of antidiabetic drug used to treat diabetes mellitus type 2. Their main mechanism of action is producing a rise in plasma insulin levels, through stimulation of insulin secretion and a decrease in hepatic clearance of insulin. Sulfonylureas include gliclazide, glipizide, glibenclamide and glimepiride.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 14
Incorrect
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The small opening in the cochlea through which the upper scala vestibuli and lower scala tympani communicates is called the:
Your Answer: Oval window
Correct Answer: Helicotrema
Explanation:The helicotrema is the part of cochlear labyrinth where the scala tympani and the scala vestibuli meet.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 15
Incorrect
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The growth promoting protein anabolic effects of insulin are mediated by:
Your Answer: Igf-1
Correct Answer: Phosphatidylinositol 3-kinase
Explanation:Phosphatidylinositol 3-kinase or PI-3Ks are a group of enzymes which are involved in a number of different cellular functions. PI-3Ks interact with insulin and the insulin receptor substrate, regulating glucose uptake. They are an important element in the insulin signalling pathway.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 16
Correct
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The hepatic portal vein is a large vessel formed by which of the following veins?
Your Answer: All of the above
Explanation:The portal vein is usually formed by the confluence of the superior mesenteric and splenic veins and also receives blood from the inferior mesenteric, gastric, and cystic veins.
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 17
Correct
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The Sinoatrial node in the majority of people is supplied by the?
Your Answer: Right coronary artery
Explanation:In 60% of people, the SA node is supplied by the right coronary artery branch and in 40% of the people by the left coronary artery.
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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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A lesion that interrupts one optic nerve causes blindness:
Your Answer: In the eye on the same side as the optic nerve
Explanation:The optic nerve on each side contains medial and lateral fibers originating from the retina. Medial fibers cross at the optic chiasm and become the optic tract ending in the visual cortex of the occipital lobe. If there is a lesion interrupting the “optic nerve” on one side, the same side eye will be completely blind.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 19
Correct
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The following is true in relation to coronary venous drainage?
Your Answer: Most venous return ultimately drains into right atrium via the coronary sinus
Explanation:Most of the venous blood returns to the heart via the coronary sinus and the anterior cardiac veins. Apart from these there are other vessels that drain directly into the heart chambers
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 20
Incorrect
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Which of the following statements are true regarding human herpesvirus eight
Your Answer: It is associated with the development of Burkitt's lymphoma.
Correct Answer: It is sexually transmitted.
Explanation:Kaposi’s sarcoma-associated herpesvirus (KSHV) is the eighth human herpesvirus or HHV-8. This virus causes Kaposi’s sarcoma, a cancer commonly occurring in AIDS patients, as well as primary effusion lymphoma and some types of multicentric Castleman’s disease. It is one of seven currently known human cancer viruses, or oncoviruses. The mechanisms by which the virus is contracted are not well understood. Healthy individuals can be infected with the virus and show no signs or symptoms, due to the immune system’s ability to keep the infection in check. Infection is of particular concern to the immunosuppressed. Cancer patients receiving chemotherapy, AIDS patients and organ transplant patients are all at a high risk of showing signs of infection. The virus is sexually transmitted.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 21
Incorrect
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What type of intercellular connection found between cardiac muscle fibers allow for the spread of excitation from one cell to another?
Your Answer: Desmosomes
Correct Answer: Gap junctions
Explanation:The cardiac muscles have gap junctions in-between the cells. They form low resistance passages, which allow ions to diffuse through every muscle fiber rapidly and result in the cardiac muscles functioning as a syncytium, without any protoplasmic bridges involved.
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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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The following determines the strength of contraction
Your Answer: Depolarization
Correct 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 23
Correct
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The pressure in the portal circulation is normally adjusted in the:
Your Answer: Sinusoids
Explanation:The pressure in the portal circulation depends on the pressure of the hepatic sinusoids mainly because the direction of transport of nutrients in the portal vein occurs from the portal vein to the hepatic sinusoids.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 24
Incorrect
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Which of the following initiates migrating motor complex
Your Answer: None of the above
Correct Answer: Motilin
Explanation:Migrating motor complexes (MMC) are thought to be partially regulated by motilin, which is initiated in the stomach as a response to vagal stimulation, and does not directly depend on extrinsic nerves.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 25
Correct
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Visceral afferent fibers are found in the following areas except the…?
Your Answer: Trigeminal nerve
Explanation:The general visceral afferent (GVA) fibers carry impulses from viscera to the central nervous system. The cranial nerves that contain GVA fibers include the facial nerve, the glossopharyngeal nerve and the vagus nerve
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This question is part of the following fields:
- Medicine
- Neurology
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Question 26
Correct
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Which of the following features occurs very less frequently with drug induced lupus?
Your Answer: Glomerulonephritis
Explanation:Drug induced lupus typically presents with pulmonary involvement and no renal or neurological involvement. Hence glomerulonephritis would be highly unlikely in this case. Rash and arthralgias are classic presentations. Pleurisy can be present as pulmonary involvement may occur with DILE.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 27
Correct
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In DNA cloning and sequencing, the bases in nucleotides chains are bound together by:
Your Answer: Hydrogen bonding.
Explanation:Nucleotides will always bind together via hydrogen bonds. There are two hydrogen bonds present between thymine and adenine and three hydrogen bonds present between guanine and cytosine.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 28
Incorrect
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What effect does osmotic diuresis have on net Na+ excretion?
Your Answer: Slightly decreased Na+ excretion
Correct Answer: Markedly increased Na+ excretionÂ
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 29
Correct
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The coronary sinus, which empties into the right atrium, serves to?
Your Answer: Drain the venous supply of the myocardium
Explanation:The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers deoxygenated blood to the right atrium, as do the superior and inferior vena cava.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 30
Correct
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Which of the following makes up the thick filaments in muscle fibers?
Your Answer: Myosin
Explanation:The thick filaments are made up of myosin and the thin filaments are made up of actin. The thick filaments are twice the size of the thin filaments and are aligned to form the A band. The thin filaments extending out from the A band form the less dense I bands.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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