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Question 1
Incorrect
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Regarding short-chain fatty acids, all the following are true except:
Your Answer: They promote Na+ absorption
Correct Answer: They are produced in the small intestine but their absorption occurs in the colon
Explanation:Short chain fatty acids (SCFAs) have carbon chains of 2-5 carbon atoms. They are produced in the large intestine and are also absorbed there. They exert a trophic effect on the colonic epithelial layer in absorption of sodium. In the absence of short chain fatty acids there is a loss of sodium and water. Transport of SCFA is coupled with sodium thus absorption leads to the accumulation in the lumen of HCO3, a rise in pH, fall in pCO2 and stimulation of Na+ and water transport. The effect on Na+ transport is thought to indicate the presence of a Na+/H+ exchange in the cell membrane.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 2
Incorrect
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In the urea cycle, which substance is formed in the mitochondria?
Your Answer: Aspartate
Correct Answer: Carbamoyl phosphate
Explanation:Before the urea cycle begins ammonia is converted to carbamoyl phosphate in the mitochondria.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 3
Correct
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Endotoxin
Your Answer: Composed of Lipid A in liposaccharide in cell wall
Explanation:Lipopolysaccharides (LPS), also known as lipoglycans and endotoxins, are large molecules consisting of a lipid (lipid A) and a polysaccharide composed of O-antigen, outer core and inner core joined by a covalent bond; they are found in the outer membrane of Gram-negative bacteria, and elicit strong immune responses in animals.
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This question is part of the following fields:
- Infectious Diseases
- Medicine
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Question 4
Incorrect
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H+ ions used in the production of acid by parietal cells is produced with the help of which enzyme?
Your Answer: Pepsinogen
Correct Answer: Carbonic anhydrase ii
Explanation:Carbonic anhydrase enzyme catalyses the rapid interconversion of carbon dioxide and water to bicarbonate and protons (or vice versa). This is a reversible reaction that takes place in the gastric parietal cells.
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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 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 6
Incorrect
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Xanthines (for example Caffeine), exhibit their positive inotropic effect by:
Your Answer: Stimulating the sympathetic catecholamine release
Correct Answer: Inhibiting the breakdown cAMP
Explanation:Xanthines exert their positive inotropic effect by inhibiting the breakdown of the cAMP resulting in stronger and sustained contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 7
Correct
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A 35 year old female, known case of anti phospholipid syndrome, arrives at the clinic due to a swollen and painful left leg. Doppler ultrasonography confirms the diagnosis of a deep vein thrombosis. She was previously diagnosed with DVT 4 months back and was on warfarin therapy (target INR 2-3) when it occurred. How should her anticoagulation be managed?
Your Answer: Life-long warfarin, increase target INR to 3 - 4
Explanation:If the INR in the range of 2-3 has still resulted in thrombosis, the target INR is increased to 3-4. However, because the risk of bleeding increases as the INR rises, the INR is closely monitored and adjustments are made as needed to maintain the INR within the target range.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 8
Correct
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Select the correct statement regarding terminal bronchioles:
Your Answer: Terminal bronchioles form part of the conducting zone
Explanation:Bronchioles divide into even smaller bronchioles, called terminal bronchioles, which are 0.5mm or less in diameter. Terminal bronchioles in turn divide into smaller respiratory bronchioles which divide into alveolar ducts. Terminal bronchioles mark the end of the conducting division of air flow in the respiratory system while respiratory bronchioles are the beginning of the respiratory division where actual gas exchange takes place. Terminal bronchioles are lined with simple cuboidal epithelium containing club cells. Terminal bronchioles contain a limited number of ciliated cells and no goblet cells. Club cells are non-ciliated, rounded protein secreting cells. Their secretions are a non-stick, proteinaceous compound (surfactant) to maintain the airway in the smallest bronchioles.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 9
Incorrect
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In which stage of mitosis are the chromosomes most obvious or prominent?
Your Answer: Telophase
Correct Answer: Metaphase
Explanation:Prophase begins when the nucleus envelope disintegrates and the chromosomes start to condense. The chromosomes consist of two sister chromatids that are joined at a constriction known as centromere. When the cell reaches the metaphase the chromosomes are completely condensed and ready to align on the equatorial plate.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 10
Correct
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The T-tubular system in cardiac muscle is:
Your Answer: Transmits action potential from sarcolemma to the SR to allow for Ca2+ release into the cytoplasm
Explanation:Action potentials are 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, which are voltage gated calcium channels.
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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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The net effect of active Vitamin D on calcium and phosphate homeostasis is?
Your Answer: Increase in Ca, increase in phosphate
Explanation:Bone and its metabolism are regulated by several hormones, amongst which is vitamin D. It is heavily involved in the metabolism and homeostasis of calcium and phosphate through several processes. Vitamin D works in the intestine, kidney, bone and parathyroid glands to maintain levels of calcium and phosphate, promoting its absorption, bone resorption, and proper functioning of the parathyroid to maintain adequate serum calcium levels.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 12
Incorrect
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Which of the following is a method for measurement of cardiac output?
Your Answer: Swan-ganz catheterization
Correct Answer: Indicator dilution method
Explanation:There are two methods of calculating the cardiac output in humans other than doppler with echocardiography: The direct Fick’s method and the indicator dilution method. In the indicator dilution technique, a known amount of a substance such as a dye or, more commonly, a radioactive isotope is injected into an arm vein and the concentration of the indicator in serial samples of arterial blood is determined. The output of the heart is equal to the amount of indicator injected divided by its average concentration in arterial blood after a single circulation through the heart.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 13
Correct
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Around 30 patients have been admitted to the hospital following a suspected chemical attack in the city. The patients are extremely unwell, with symptoms of excessive salivation, lacrimation, diarrhoea, and emesis. Sarin gas was suspected as the most likely agent used in the attack. What is the mechanism of action of this chemical agent?
Your Answer: Inhibition of acetylcholinesterase
Explanation:Sarin acts by inhibiting acetylcholinesterase.Sarin gas is a highly toxic synthetic organophosphorus compound which causes inhibition of the enzyme acetylcholinesteraseSarin gas is a highly toxic synthetic organophosphorus compound which causes inhibition of the enzyme acetylcholinesterase. This results in high levels of acetylcholine (ACh).The effects of excessive ACh can be remembered by the mnemonic DUMBELLS:DiarrhoeaUrinationMiosis/muscle weaknessBronchorrhea/BradycardiaEmesisLacrimationSalivation/sweatingOrganophosphate insecticide poisoning:One of the effects of organophosphate poisoning is inhibition of acetylcholinesteraseFeatures can be predicted by the accumulation of acetylcholine (mnemonic = SLUD)SalivationLacrimationUrinationDefecation/diarrhoeacardiovascular: hypotension, bradycardiamiosis, muscle fasciculation.Organophosphate poisoning is treated with the anti-muscarinic atropine.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 14
Correct
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The only APCs that can activate naive T lymphocytes are:
Your Answer: Dendric cells
Explanation:Only professional antigen-presenting cells (macrophages, B lymphocytes, and dendritic cells) are able to activate a resting helper T-cell when the matching antigen is presented. However, macrophages and B cells can only activate memory T cells whereas dendritic cells can activate both memory and naive T cells, and are the most potent of all the antigen-presenting cells.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 15
Correct
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The function of ATP in cardiac muscle contraction includes:
Your Answer: Binding to myosin after the power stroke to allow uncoupling of actin and myosin
Explanation:After calcium binds to the troponin C, there is a conformational change in the structure of troponin I and tropomyosin, which moves out of the way and frees the site where myosin can bind to actin. This results in the formation of the cross linkage of the actin and myosin giving rise to the power stroke in the contraction phase. This occurs with the release of ADP. When ATP combines to this complex it breaks and the cycle repeats itself.
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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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A 30-year-old female presents with a 4-day history of diarrhoea and vomiting. She has been unable to keep fluids down for 4 days and has been treated with metoclopramide. She develops a dystonic reaction. What is the most appropriate treatment for this woman?
Your Answer: Flupentixol
Correct Answer: Benztropine
Explanation:Acute dystonic reactions (extrapyramidal symptoms) such as spasmodic torticollis, trismus, and oculogyric crises can occur following the administration of metoclopramide or stemetil and thus, neither is recommended for the treatment of nausea in young women.
Such reactions respond well to treatment with benztropine or procyclidine.
– Benztropine: It is an anticholinergic medication with significant CNS penetration. A single dose of benztropine 1 to 2 mg IV followed by 1 to 2 mg p.o twice a day for up to 7 days to prevent a recurrence. Subsequently, both the offending agent and those from the same group should be avoided.
– Alternatively, diphenhydramine can be used intravenously (up to a dose of 50mg) or intramuscularly followed by p.o therapy every 6 hours for 1 to 2 to prevent a recurrence.- Second-line therapy with IV benzodiazepines is reserved for those patients who do not respond to anticholinergics.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 17
Correct
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Concerning the sleep-wake cycle, Melatonin is secreted by which structure in the brain following which environmental conditions?
Your Answer: Pineal gland, darkness
Explanation:Melatonin is secreted by the pineal gland located in the midline attached to the posterior roof of the third ventricle in the brain. Melatonin affects circadian rhythm in the body or the sleep wake cycle. The precursor to melatonin is serotonin and the rate limiting enzyme that converts serotonin to melatonin is low during the day time and reaches its peak during the night.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 18
Correct
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What percentage of blood to the liver is supplied by hepatic artery?
Your Answer: 25%
Explanation:The liver receives a dual blood supply from the hepatic portal vein and hepatic arteries. The hepatic portal vein delivers approximately 75% of the liver’s blood supply, and carries venous blood drained from the spleen, gastrointestinal tract, and its associated organs. The hepatic arteries supply arterial blood to the liver, accounting for the remaining quarter of its blood flow.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 19
Correct
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Salty taste is triggered by:
Your Answer: Amiloride-sensitive sodium channel
Explanation:Amiloride-sensitive sodium channels also known as epithelial Na channels is a membrane bound ion channel that is selectively permeable to Na+ ions. These channels are located throughout different epithelial membranes in the body. It is found in taste receptor cells, where it plays an important role in salt taste perception. They are also located in the kidney, the lung and the colon. Hyperpolarization-activated, cyclic nucleotide-gated (HCN) voltage-gated ion channels are widely seen in the cortex, hippocampus, thalamus and brain regions that underlie the generation of both focal and generalized-onset seizures. The metabotropic glutamate receptor (mGluRs) perform a variety of functions in the central and peripheral nervous systems. They are involved in learning, memory, anxiety, and the perception of pain. Gustducin is a G protein associated with taste and gustatory system. It plays a major role in sensation of bitter, sweet and umami stimuli.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 20
Correct
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A 22-year-old female comes to you for counselling regarding the initiation of combined oral contraceptive pill. Which of the following statements is correct?
Your Answer: She will still be protected against pregnancy if she takes amoxicillin for a lower respiratory tract infection while on the combined pill
Explanation:The true statement among the given options is that she will still be protected against pregnancy if she takes amoxicillin for a lower respiratory tract infection while on the combined pill.Other than enzyme-inducing antibiotics such as rifampicin, antibiotics do not reduce the efficacy of the combined oral contraceptive pill.It was previously advised that barrier methods of contraception should be used if taking an antibiotic while using the contraceptive pill, due to concerns that antibiotics might reduce the absorption of the pill. This is now known to be untrue. However, if the absorptive ability of the gut is compromised for another reason, such as severe diarrhoea or vomiting, or bowel disease, this may affect the efficacy of the pill.The exception to the antibiotic rule is that hepatic enzyme-inducing antibiotics such as rifampicin and rifaximin do reduce the efficacy of the pill. Other enzyme-inducing drugs, such as phenytoin, phenobarbital, carbamazepine or St John’s Wort can also reduce the effectiveness of the pill.Other options:The combined pill is often prescribed for women with heavy periods as it can make them lighter and less painful. There is no evidence that women on the combined pill put on any significant weight, although they may experience bloating at certain times in the course. Women on the pill require monitoring of their blood pressure. There are multiple different types of combined pills.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 21
Incorrect
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Regarding the formation of CSF, which of the following is true?
Your Answer: Brain interstitial fluid and CSF do not communicate freely
Correct Answer: Its composition resembles that of brain ECF
Explanation:In normal adults CSF volume is around 125ml to 150ml. Turnover of entire volume of cerebrospinal fluid a day 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 a different electrolyte level. About 80% of CSF is produced by the choroid plexus. It is also produced by a single layer of column shaped ependymal cells. The composition and rate of CSF generation depends on several factors and is influenced by hormones and the content and pressure of blood and CSF.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 22
Correct
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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 23
Correct
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Cold receptors are likely to be active at the following temperatures except?
Your Answer: 39 °C
Explanation:Cold and Menthol receptor 1 (CMR1) is a protein that in humans is encoded by TRPM8 gene. It is primarily responsible for the detection of temperatures ranging from 8-28 C. It is an ion channel which upon activation causes the influx of Na+ and Ca+ ions into the cell that leads to the depolarization and generation of an action potential.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 24
Correct
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Where does the anterior pituitary receive most of its blood supply?
Your Answer: Portal hypophysial vessels
Explanation:The anterior pituitary receives its arterial supply from the superior hypophyseal artery, which is a branch of the internal carotid that forms a capillary around the hypothalamus; thus forming the hypothalamo-hypophysial portal system.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 25
Correct
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Efferent innervation of the muscle spindle is supplied by which type of motor neuron?
Your Answer: Gama – motor neuron
Explanation:The muscle spindle is supplied by both sensory and motor nerves. Sensory supply is via Type Ia fibers whereas the motor supply is via gamma motor neurons.
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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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What catalyses the conversion of adenosine to inosine?
Your Answer: Adenosine deaminase
Explanation:Adenosine deaminase (ADA) is an enzyme involved in purine metabolism. It is needed for the breakdown of adenosine from food and for the turnover of nucleic acids in tissues. ADA irreversibly deaminates adenosine, converting it to the related nucleoside inosine by the substitution of the amino group for a keto group.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 27
Incorrect
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The enzyme responsible for telomeres maintaining their length after cell division is called:
Your Answer: Telomere transcriptase
Correct Answer: Telomerase
Explanation:Telomerase is the enzyme responsible for maintenance of the length of telomeres by addition of guanine-rich repetitive sequences. Telomerase activity is exhibited in gametes and stem and tumor cells.
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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 is the function of gap junctions?
Your Answer: Fastening cells together
Correct Answer: Diffusion of small molecules between neighbouring cells
Explanation:Gap junctions are a specialized intercellular connection between a multitude of cell-types. They directly connect the cytoplasm of two cells, which allows various molecules, ions and electrical impulses to directly pass through a regulated gate between cells.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 29
Incorrect
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The spinal cord receive its blood supply from the following arteries except:
Your Answer: Segmental radicular arteries
Correct 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 30
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:
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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SESSION STATS - PERFORMANCE PER SPECIALTY
