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Question 1
Incorrect
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A study's objective is to find the normal reference range for IgE levels in the adult population. What percentage of individuals will have IgE levels higher than 2 standard deviations from the mean, assuming that the IgE levels follow a normal distribution?
Your Answer: 1.25%
Correct Answer: 2.30%
Explanation:Normal distribution describes the spread of many biological and clinical measurements. Usually, 68.3% lies within 1 standard deviation (SD) of the mean, 95.4% lies within 2 SD of the mean and 99.7% lies within 3 SD of the mean.
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This question is part of the following fields:
- Clinical Sciences
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Question 2
Incorrect
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Which one of the following statements best describes a type II statistical error?
Your Answer:
Correct Answer: The null hypothesis is accepted when it is false
Explanation:In statistical hypothesis testing there are 2 types of errors:
– type I: the null hypothesis is rejected when it is true – i.e. Showing a difference between two groups when it doesn’t exist, a false positive.
– type II: the null hypothesis is accepted when it is false – i.e. Failing to spot a difference when one really exists, a false negative. -
This question is part of the following fields:
- Clinical Sciences
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Question 3
Incorrect
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A 34-year-old male patient is admitted with hemisection of the spinal cord at the level T5, after being stabbed in the back. Which sign would you expect to see by assessing the patient's sensory function and muscle strength?
Your Answer:
Correct Answer: Contralateral loss of temperature, ipsilateral loss of fine touch and vibration, ipsilateral spastic paresis
Explanation:Depending on the level of SCI, patients experience paraplegia or tetraplegia. Paraplegia is defined as the impairment of sensory or motor function in lower extremities. Patients with incomplete paraplegia generally have a good prognosis in regaining locomotor ability (,76% of patients) within a year. Complete paraplegic patients, however, experience limited recovery of lower limb function if their NLI is above T9. The spinothalamic tract is the one responsible for sensory information such as pain or temperature. However, it decussates at the same level the nerve root enters the spinal cord, meaning that the sensory loss will be contralateral. However, the dorsal column carries sensory fibres for fine touch and vibration and it decussates at the medulla which means that the sensory loss will be ipsilateral. The corticospinal tract is responsible for motor functions and it decussates at the medulla, meaning that the motor function loss will be ipsilateral.
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This question is part of the following fields:
- Clinical Sciences
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Question 4
Incorrect
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A 21-year-old man presents with a three day history of general malaise and low-grade temperature. Yesterday he developed extensive painful ulceration of his mouth and gums. On examination his temperature is 37.4ºC, pulse 84 / min and there is submandibular lymphadenopathy. What is the most likely diagnosis?
Your Answer:
Correct Answer: Herpes simplex virus infection
Explanation:This man has gingivostomatitis, a characteristic feature of primary herpes simplex virus infection. Herpetic gingivostomatitis is often the initial presentation during the first (primary) herpes simplex infection. It is of greater severity than herpes labialis (cold sores) which is often the subsequent presentations. Primary herpetic gingivostomatitis is the most common viral infection of the mouth.
Primary herpetic gingivostomatitis (PHGS) is caused predominantly by HSV-1 and affects mainly children. Prodromal symptoms, such as fever, anorexia, irritability, malaise and headache, may occur in advance of disease. Sub-mandibular lymphadenitis, halitosis and refusal to drink are usual concomitant findings. -
This question is part of the following fields:
- Clinical Sciences
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Question 5
Incorrect
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Intracellular proteins tagged with mannose-6-phosphate are destined to which of the following organelles?
Your Answer:
Correct Answer: Lysosome
Explanation:Lysosomal hydrolases are synthesized in the rough endoplasmic reticulum and specifically transported through the Golgi apparatus to the trans-Golgi network, from which transport vesicles bud to deliver them to the endosomal/lysosomal compartment. The explanation of how the lysosomal enzymes are accurately recognized and selected over many other proteins in the trans-Golgi network relies on them being tagged with a unique marker: the mannose-6-phosphate (M6P) group, which is added exclusively to the N-linked oligosaccharides of lysosomal soluble hydrolases, as they pass through the cis-Golgi network. Generation of the M6P recognition marker depends on a reaction involving two different enzymes: UDP-N-acetylglucosamine 1-phosphotransferase and α-N-acetylglucosamine-1-phosphodiester α-N-acetylglucosaminidase.
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This question is part of the following fields:
- Clinical Sciences
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Question 6
Incorrect
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A 34-year-old man presents with haemoptysis and weight loss. History reveals he suffers from night sweats and upon auscultation you notice reduced breath sounds over the apex of his right lung and significant nail clubbing. You refer him to a pneumologist who administers the following antibiotics: rifampicin, ethambutol, pyrazinamide and isoniazid. What is the mechanism of action of the first drug?
Your Answer:
Correct Answer: Inhibit RNA synthesis
Explanation:Rifampicin specifically inhibits bacterial RNA polymerase, the enzyme responsible for DNA transcription, by forming a stable drug-enzyme complex with a binding constant of 10(-9) M at 37 C.
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This question is part of the following fields:
- Clinical Sciences
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Question 7
Incorrect
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A 42-year-old man with a 6 month history of progressive weakness of both lower limbs, complains of lethargy and of difficulties climbing stairs. He also claims he's experienced muscle loss in his lower limbs. History reveals type 2 diabetes mellitus and heavy alcohol use for the last 4 years. Clinical examination reveals marked loss of fine touch and proprioception. The distribution is in a stocking manner and bilateral. However, no evidence of ataxia is present. What is the most probable diagnosis?
Your Answer:
Correct Answer: Dry beriberi
Explanation:Hypovitaminosis B1, consistent with dry beriberi is crucially a treatable condition, although sometimes with incomplete recovery, but it is probably under-recognized yet increasingly common given increasing levels of alcohol abuse in the western world. Dry beriberi or ‘acute nutritional polyneuropathy’ is considered to be rare in the western world. Rapid deterioration can occur, typically with weakness, paraesthesia and neuropathic pain. Striking motor nerve involvement can occur, mimicking Guillain-Barré syndrome (GBS). In the context of increasing alcohol abuse in the western world, it is possible that alcoholic neuropathy associated with abrupt deterioration due to concomitant nutritional hypovitaminosis B1 may be seen increasingly often.
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This question is part of the following fields:
- Clinical Sciences
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Question 8
Incorrect
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A woman with severe renal failure undergoes a kidney transplant. However, after a few hours, she develops fever and anuria. The doctors are suspecting hyperacute organ rejection. Which are the cells primarily responsible for hyperacute organ rejection?
Your Answer:
Correct Answer: B Cells
Explanation:Hyperacute rejection appears in the first minutes following transplantation and occurs only in vascularized grafts. This very fast rejection is characterized by vessel thrombosis leading to graft necrosis. Hyperacute rejection is caused by the presence of antidonor antibodies existing in the recipient before transplantation. These antibodies induce both complement activation and stimulation of endothelial cells to secrete Von Willebrand procoagulant factor, resulting in platelet adhesion and aggregation. The result of these series of reactions is the generation of intravascular thrombosis leading to lesion formation and ultimately to graft loss. Today, this type of rejection is avoided in most cases by checking for ABO compatibility and by excluding the presence of antidonor human leukocyte antigen (HLA) antibodies by cross-match techniques between donor graft cells and recipient sera. This type of rejection is also observed in models of xenotransplantation of vascularized organs between phylogenetically distant species when no immunosuppressive treatment is given to the recipients.
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This question is part of the following fields:
- Clinical Sciences
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Question 9
Incorrect
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Choose the most important stimulator of the central chemoreceptors:
Your Answer:
Correct Answer: Decrease in pH
Explanation:Central chemoreception refers to the detection of changes in CO2/H+ within the brain and the associated effects on breathing. In the conscious animal the response of ventilation to changes in the brain’s interstitial fluid (ISF) pH is very sensitive. Note that a small change in cerebrospinal fluid (CSF) pH from 7.30 to 7.25 is associated with a doubling of alveolar ventilation; it is a very sensitive reflex response. Note also that the relationship of alveolar ventilation to ISF pH is essentially the same for both types of stimulation, metabolic acid-base disorders and primary CO2 stimulation.
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This question is part of the following fields:
- Clinical Sciences
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Question 10
Incorrect
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Which one of the following statements regarding interleukin 1 (IL-1) is true?
Your Answer:
Correct Answer: It is released mainly by macrophages/monocytes
Explanation:Interleukin 1 alpha and interleukin 1 beta (IL1 alpha and IL1 beta) are cytokines that participate in the regulation of immune responses, inflammatory reactions, and hematopoiesis. It is secreted mainly by macrophages and monocytes and acts as a costimulator of T cell and B cell proliferation.
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This question is part of the following fields:
- Clinical Sciences
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Question 11
Incorrect
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A study is developed to compare the calcemia of men and women with Crohn's disease. The objective of the study is to detect any differences between the average calcium levels in men compared to women. Previous studies have shown a normal distribution regarding calcium levels. Which of the the following tests would you most likely apply?
Your Answer:
Correct Answer: Student's unpaired t-test
Explanation:A t test is a type of statistical test that is used to compare the means of two groups. It is one of the most widely used statistical hypothesis tests in pain studies. There are two types of statistical inferences: parametric and nonparametric methods. Parametric methods refer to a statistical technique in which one defines the probability distribution of probability variables and makes inferences about the parameters of the distribution. In cases in which the probability distribution cannot be defined, nonparametric methods are employed. T tests are a type of parametric method; they can be used when the samples satisfy the conditions of normality, equal variance, and independence. In this case the data is parametric, comparing two independent samples from the same population.
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This question is part of the following fields:
- Clinical Sciences
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Question 12
Incorrect
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Where is secretin secreted from?
Your Answer:
Correct Answer: S cells in upper small intestine
Explanation:Secretin is a peptide hormone produced in the S cells of the duodenum, which are located in the intestinal glands. In humans, the secretin peptide is encoded by the SCT gene.
Secretin helps regulate the pH of the duodenum by
1) inhibiting the secretion of gastric acid from the parietal cells of the stomach and
(2) stimulating the production of bicarbonate from the ductal cells of the pancreas.
G cells in the antrum of the stomach release gastrin
I cells in upper small intestine release CCK
D cells in the pancreas & stomach secrete somatostatin
K cells secrete gastric inhibitory peptide, an incretin, which also promotes triglyceride storage. -
This question is part of the following fields:
- Clinical Sciences
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Question 13
Incorrect
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What percentage of values lie within 3 standard deviations of the mean in a normal distribution?
Your Answer:
Correct Answer: 99.70%
Explanation:Normal distribution describes the spread of many biological and clinical measurements. Usually, 68.3% lies within 1 standard deviation (SD) of the mean, 95.4% lies within 2 SD of the mean and 99.7% lies within 3 SD of the mean.
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This question is part of the following fields:
- Clinical Sciences
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Question 14
Incorrect
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Which of the following suggests a diagnosis of molluscum contagiosum rather than chickenpox?
Your Answer:
Correct Answer: Absence of erythema surrounding lesions
Explanation:Molluscum contagiosum (MC), is a viral infection of the skin that results in small, raised, pink lesions with a dimple in the center with little to no surrounding erythema. They may occasionally be itchy or sore. They may occur singularly or in groups. Any area of the skin may be affected, with abdomen, legs, arms, neck, genital area, and face being most common. Onset of the lesions is around 7 weeks after infection. It usually goes away within a year without scarring.
Chickenpox lesions in the early stages may be mistaken for molluscum. However, the presence of associated macules and later vesicles and pustules help to differentiate them. -
This question is part of the following fields:
- Clinical Sciences
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Question 15
Incorrect
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A clinical trial is conducted to study the benefits of a new oral medication to improve the symptoms of patients with asthma. In the trial 400 patients with asthma, half were given the new medication and half a placebo. Three months later they are asked to rate their symptoms using the following scale: much improved, slight improvement, no change, slight worsening, significantly worse. What is the most appropriate statistical test to see whether the new medication is beneficial?
Your Answer:
Correct Answer: Mann-Whitney U test
Explanation:The type of significance test used depends on whether the data is parametric (can be measured, usually normally distributed) or non-parametric.
Parametric tests:
Student’s t-test – paired or unpaired*
Pearson’s product-moment coefficient – correlationNon-parametric tests:
Mann-Whitney U test – unpaired data
Wilcoxon signed-rank test – compares two sets of observations on a single sample
chi-squared test – used to compare proportions or percentages
Spearman, Kendall rank – correlation.The outcome measured is not normally distributed, i.e. it is non-parametric. This excludes the Student’s t-tests. We are not comparing percentages/proportions so the chi-squared test is excluded. The Mann–Whitney U test is a nonparametric test of the null hypothesis that it is equally likely that a randomly selected value from one sample will be less than or greater than a randomly selected value from a second sample.
This test can be used to investigate whether two independent samples were selected from populations having the same distribution. -
This question is part of the following fields:
- Clinical Sciences
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Question 16
Incorrect
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A 22-year-old man presents with red and flaky patches at the corners of his mouth. Upon examination, angular cheilitis is diagnosed. Anamnesis reveals a history of excessive drinking and malnutrition. What is the most probable deficiency responsible for his condition?
Your Answer:
Correct Answer: Vitamin B2 deficiency
Explanation:Riboflavin, vitamin B2, is a water-soluble and heat-stable vitamin that the body uses to metabolize fats, protein, and carbohydrates into glucose for energy. Riboflavin deficiency can cause fatigue, swollen throat, blurred vision, and depression. It can affect the skin by causing skin cracks, itching, and dermatitis around the mouth. Hyperaemia and oedema around throat, liver degeneration, and hair loss can also occur along with reproductive issues. Usually, people with riboflavin deficiency also have deficiencies of other nutrients. In most cases, riboflavin deficiency can be reversed unless it has caused anatomical changes such as cataracts.
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This question is part of the following fields:
- Clinical Sciences
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Question 17
Incorrect
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Which one of the following statements regarding mitochondrial inheritance is true?
Your Answer:
Correct Answer: Poor genotype:phenotype correlation
Explanation:The human cell has two type of DNA: Nuclear DNA and Mitochondrial DNA (MtDNA). A MtDNA copy is passed down entirely unchanged, through the maternal line. Males cannot pass their MtDNA to their offspring although they inherit a copy of it from their mother. There is poor genotype:phenotype correlation. Within a tissue or cell there can be different mitochondrial populations (this is known as heteroplasmy).
Examples of mitochondrial diseases include:
– Leber’s optic atrophy
– MELAS syndrome (mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes)
– MERRF syndrome (myoclonus epilepsy with ragged-red fibres)
– Kearns-Sayre syndrome (more severe syndromic variant of chronic progressive external ophthalmoplegia, onset in patients < 20 years old) -
This question is part of the following fields:
- Clinical Sciences
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Question 18
Incorrect
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Question 19
Incorrect
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A 62year-old manpresents with exertional chest pain and is found to have extensive coronary artery disease on angiogram. Which of the following cell types is most implicated in the development of coronary artery plaques?
Your Answer:
Correct Answer: Macrophages
Explanation:An atheroma is an accumulation of degenerative material in the tunica intima (inner layer) of artery walls. The material consists of (mostly) macrophage cells, or debris, containing lipids (cholesterol and fatty acids), calcium and a variable amount of fibrous connective tissue.
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This question is part of the following fields:
- Clinical Sciences
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Question 20
Incorrect
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A 54-year-old man is found collapsed in the street and is brought to the A&E. The results from the blood tests reveal Calcium = 1.62mmol/l and Albumin = 33g/l. The man is known to have a history of alcoholic liver disease. Which of the following is the best management regarding his calcium levels?
Your Answer:
Correct Answer: 10ml of 10% calcium gluconate over 10 minutes
Explanation:Acute, symptomatic hypocalcaemia is treated with 10ml of 10% calcium gluconate over 10 minutes.
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This question is part of the following fields:
- Clinical Sciences
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Question 21
Incorrect
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A 2-day-old girl is admitted by her mother because she gets cyanotic upon feeding and she wouldn't stop crying. The doctors suspect a congenital heart disease. What is the most probable aetiology?
Your Answer:
Correct Answer: Transposition of the great arteries
Explanation:Transposition of the great arteries results in a significant hypoxemic status that is observed clinically by central cyanosis. The bluish discoloration of the skin and mucous membranes is therefore the basic pattern of clinical presentation in transposition. Its onset and severity depend on anatomical and functional variants that influence the degree of mixing between the two circulations. Limited intercirculatory mixing, usually present if the ventricular septum is intact or the atrial septal defect is restrictive, is related to progressive and profound central cyanosis evident within the first hours of life. Tachypnoea, tachycardia, diaphoresis, poor weight gain, a gallop rhythm, and eventually hepatomegaly can be then detected later on during infancy. Heart murmurs associated with left outflow tract obstruction, due to a persistent arterial duct or a septal defect may be heard, but they are not a constant finding.
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This question is part of the following fields:
- Clinical Sciences
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Question 22
Incorrect
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A literature review of a number of studies was conducted to assess the potential efficacy of a new drug, which may reduce the chance of patients with chronic kidney disease (CKD) developing gout. In one study 120 out of 1,200 patients receiving the new drug developed gout. The total number of the patients were 2,000 and the remaining 800 individuals received a placebo. From the patients that had received the placebo, 200 developed gout. What is the absolute risk reduction of developing gout?
Your Answer:
Correct Answer: 15%
Explanation:Absolute risk reduction (ARR) – also called risk difference (RD) – is the most useful way of presenting research results to help your decision-making. Absolute risk reduction = (Control event rate) – (Experimental event rate) = 0.15 = 15%
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This question is part of the following fields:
- Clinical Sciences
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Question 23
Incorrect
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Sensorineural deafness is strongly associated with which one of the following?
Your Answer:
Correct Answer: Rubella
Explanation:Primary rubella infection during pregnancy, particularly during the first trimester, can affect several organs and cause birth defects that are responsible for congenital rubella syndrome (CRS). The most common defects of CRS are hearing impairment (unilateral or bilateral sensorineural), eye defects (e.g., cataracts, congenital glaucoma, or pigmentary retinopathy), and cardiac defects (e.g., patent ductus arteriosus or peripheral pulmonic stenosis). Congenital hearing loss is the most common sequela, occurring in approximately 60% of cases, especially when infection occurs in the 4th month of pregnancy.
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This question is part of the following fields:
- Clinical Sciences
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Question 24
Incorrect
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Choose the karyotype associated with short stature:
Your Answer:
Correct Answer: 45,XO
Explanation:Turner syndrome (TS) is one of the most common genetic disorders; occurs with an incidence of I: 2,500 female live births. It results from complete or partial chromosome X monosomy. TS is associated with abnormalities of the X chromosome and characteristic clinical features of short stature, gonadal dysgenesis, sexual developmental deficiencies, cardiac and/or renal defects, webbed neck, low-set ears, skeletal deformities including cubitus valgus, a propensity to ear infections and hearing deficits.
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This question is part of the following fields:
- Clinical Sciences
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Question 25
Incorrect
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Choose the molecule that acts as the co-receptor for cells expressing antigens linked with MHC class I molecules:
Your Answer:
Correct Answer: CD8
Explanation:CD8+ T cells recognize antigens in the form of short peptide fragments bound to major histocompatibility complex class I (MHCI) molecules on the target cell surface.1 Specific engagement of peptide-MHCI (pMHCI) complexes via the clonotypically expressed αβ T-cell receptor (TCR) triggers a range of effector functions that play a critical role in protective immunity against intracellular infections and various malignancies.
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This question is part of the following fields:
- Clinical Sciences
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Question 26
Incorrect
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Through which foramen does the maxillary nerve pass through?
Your Answer:
Correct Answer: Foramen rotundum
Explanation:The foramen rotundum is one of the several circular apertures (the foramina) located in the base of the skull, in the anterior and medial part of the sphenoid bone. The maxillary branch (V2) of the trigeminal nerve (CN V) passes through and exits the skull via the pterygopalatine fossa and the foramen rotundum.
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This question is part of the following fields:
- Clinical Sciences
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Question 27
Incorrect
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A 13-year-old girl presents with a swollen left knee following a fall. Her parents state she suffers from haemophilia and has been treated for a right-sided haemarthrosis previously. What other condition is she most likely to have?
Your Answer:
Correct Answer: Turner's syndrome
Explanation:Haemophilia is a X-linked recessive disorder. In X-linked recessive inheritance only males are affected. An exception to this seen in examinations are patients with Turner’s syndrome, who are affected due to only having one X chromosome. X-linked recessive disorders are transmitted by heterozygote females (carriers) and male-to-male transmission is not seen. Affected males can only have unaffected sons and carrier daughters.
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This question is part of the following fields:
- Clinical Sciences
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Question 28
Incorrect
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A 54-year-old female patient presents with a one week history of bloody diarrhoea, fever and abdominal pain. She has a history of rheumatoid arthritis which she controls with methotrexate. Her stool sample shows Campylobacter jejuni. What is the single most appropriate management?
Your Answer:
Correct Answer: Fluids + clarithromycin
Explanation:This woman is receiving methotrexate, an immunosuppressant, to control her rheumatoid arthritis. In such immunocompromised patients, BNF suggests clarithromycin as first-line management.
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This question is part of the following fields:
- Clinical Sciences
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Question 29
Incorrect
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A study is developed to assess a new mandible advancement device designed to reduce snoring. A 10 point scale was used to assess the severity of snoring before and after applying of the device by the respective partner. The number of the people involved in the study was 50. What test would you apply in this particular study?
Your Answer:
Correct Answer: Wilcoxon signed-rank test
Explanation:Steps required in performing the Wilcoxon signed rank test:
1 State the null hypothesis and, in particular, the hypothesized value for comparison
2 Rank all observations in increasing order of magnitude, ignoring their sign. Ignore any observations that are equal to the hypothesized value. If two observations have the same magnitude, regardless of sign, then they are given an average ranking
3 Allocate a sign (+ or -) to each observation according to whether it is greater or less than the hypothesized value (as in the sign test)
4 Calculate:
R+ = sum of all positive ranks
R- = sum of all negative ranks
R = smaller of R+ and R-
5 Calculate an appropriate P value What makes this test the most appropriate for this study is that the data is non-parametric, paired and comes from the same population. -
This question is part of the following fields:
- Clinical Sciences
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Question 30
Incorrect
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Choose the correct formula to calculate the negative predictive value of a screening test:
Your Answer:
Correct Answer: TN / (TN + FN)
Explanation:NPV = TN / FN+TN
= TN (true negative) / FN+TN (false negative + true negative)
= Probability (patient not having disease when test is negative)
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This question is part of the following fields:
- Clinical Sciences
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