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Question 1
Correct
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Which part of the renal tubule is impermeable to water:
Your Answer: The ascending limb of loop of Henle
Explanation:The walls of the ascending limb of the loop of Henle are not permeable to water. The tubular fluid thus becomes increasingly dilute as it ascends toward the cortex, whereas the interstitial fluid around the loops of Henle in the medulla becomes increasingly more concentrated.
The ascending limb actively reabsorbs NaCl but has an extremely low transepithelial osmotic water permeability, even in the presence of vasopressin. This combination of NaCl reabsorption without water reabsorption serves two vital functions: it provides NaCl to increase the osmolality of the medullary interstitium, tubules, vasculature, and collecting ducts; and it dilutes the luminal fluid within the thick ascending limb.
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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 is the most common chromosomal defect in Down's syndrome?
Your Answer: Trinucleotide repeat disorder
Correct Answer: Non-dysjunction
Explanation:Nondisjunction of chromosome 21 is the leading cause of Down syndrome. Two risk factors for maternal nondisjunction of chromosome 21 are increased maternal age and altered recombination.
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This question is part of the following fields:
- Clinical Sciences
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Question 3
Incorrect
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A 68-year-old male patient presents with central chest pain and associated flushing. He claims the pain is crushing in character. ECG reveals T wave inversion in II, III and AVF. Blood exams are as follows: Troponin T = 0.9 ng/ml. Which substance does troponin bind to?
Your Answer: Calcium ions
Correct Answer: Tropomyosin
Explanation:Troponin T is a 37 ku protein that binds to tropomyosin, thereby attaching the troponin complex to the thin filament.
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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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Which one of the following statements regarding mitochondrial inheritance is true?
Your Answer: Friedreich's ataxia is caused by defects in mitochondrial DNA
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 5
Incorrect
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What percentage of values lie within 3 standard deviations of the mean in a normal distribution?
Your Answer: 98.30%
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 6
Correct
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What kind of receptor is the nitric oxide receptor?
Your Answer: Guanylate cyclase receptor
Explanation:Soluble guanylyl cyclase (GC-1) is the primary receptor of nitric oxide (NO) in smooth muscle cells and maintains vascular function by inducing vasorelaxation in nearby blood vessels. GC-1 converts guanosine 5′-triphosphate (GTP) into cyclic guanosine 3′,5′-monophosphate (cGMP), which acts as a second messenger to improve blood flow.
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This question is part of the following fields:
- Clinical Sciences
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Question 7
Correct
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Where is secretin secreted from?
Your 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 8
Correct
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A study is carried out to assess the efficacy of a rapid urine screening test developed to detect Chlamydia. The total number of people involved in the study were 200. The study compared the new test to the already existing NAAT techniques. The new test was positive in 20 patients that were Chlamydia positive and in 3 patients that were Chlamydia negative. For 5 patients that were Chlamydia positive and 172 patients that were Chlamydia negative the test turned out to be negative. Choose the correct value regarding the negative predictive value of the new test:
Your Answer: 172/177
Explanation:The definition of negative predictive value is the probability that the individuals with truly negative screening test don’t have Chlamydia. The equation is the following: Negative predictive value = Truly negative/(truly negative + false negative) = 172 / (172 + 5) = 172 / 177
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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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Which one of the following congenital infections is most characteristically associated with chorioretinitis?
Your Answer: Cytomegalovirus
Correct Answer: Toxoplasma gondii
Explanation:The common congenital infections encountered are rubella, toxoplasmosis and cytomegalovirus. Cytomegalovirus is the most common congenital infection in the UK. Maternal infection is usually asymptomatic.
Congenital toxoplasmosis is associated with fetal death and abortion, and in infants, it is associated with neurologic deficits, neurocognitive deficits, and chorioretinitis. -
This question is part of the following fields:
- Clinical Sciences
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Question 10
Incorrect
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A 55-year-old female with a history of osteoarthritis of the knee, obesity and depression, presents with neck and right arm pain. She claims that the pain is present for two months and is triggered by flexing her neck. Clinical examination reveals sensory loss over the middle finger and palm of the hand without any obvious muscle atrophy or weakness. Which nerve root is most probably affected?
Your Answer: C6
Correct Answer: C7
Explanation:The most common cause of cervical radiculopathy is degenerative disease in the cervical spine. In 80–90% of patients with cervical radiculopathy, the C5/C6 or C6/C7 motion segments are affected by degenerative disease and the nearby C6 and/or C7 nerve roots are producing the symptoms. Patients with cervical radiculopathy complain of neck pain and radiating pain in the arm sometimes combined with sensory and motor disturbances in the arm and/or hand. These symptoms are accepted as being caused by the nerve root compression. Middle finger and palm of the hand are mostly rising the suspicion for C7 nerve root and median nerve involvement.
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This question is part of the following fields:
- Clinical Sciences
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Question 11
Correct
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A new blood test developed to screen individuals for cardiac failure was performed on 500 patients. The results were positive for 40 out of 50 patients with echocardiography-established heart failure. However, the test was also positive for 20 patients with no signs of heart failure. What is the positive predictive value of the test?
Your Answer: 0.66
Explanation:Positive predictive value = TP (true positives) / [TP + FP (false positives)] = 40 / (40 + 20) = 0.66
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This question is part of the following fields:
- Clinical Sciences
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Question 12
Correct
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A 22-year-old man is investigated for visual loss and diagnosed with Leber's optic atrophy. Given the mitochondrial inheritance of this condition, which one of the following relatives is most likely to be also affected?
Your Answer: Sister
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. Mitochondrial inheritance therefore has the following characteristics:
– Inheritance is only via the maternal line
– All children of affected males will not inherit the disease
– All children of affected females will inherit it -
This question is part of the following fields:
- Clinical Sciences
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Question 13
Incorrect
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The average weight of 64 patients with type 2 diabetes mellitus was 81 kg, with a standard deviation of 12 kg. What is the standard error of the mean?
Your Answer: Square root (64 / 12)
Correct Answer: 1.5
Explanation:The SEM is dependent on the variation in the population and the number of the extracted samples. A large variation in the population causes a large difference in the sample means, ultimately resulting in a larger SEM. However, as more samples are extracted from the population, the sample means move closer to the population mean, which results in a smaller SEM. In short, the SEM is an indicator of how close the sample mean is to the population mean. Standard error of the mean = standard deviation / square root (number of patients)
The standard error of the mean is calculated by the standard deviation / square root (number of patients)= 12 / square root (64) = 12 / 8 = 1.5
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This question is part of the following fields:
- Clinical Sciences
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Question 14
Correct
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A 60-year-old male presents with dyspnoea and an urgent chest X-ray is scheduled. Sputum cultures reveal pneumonia and he receives treatment with erythromycin. What is the mechanism of action of this drug?
Your Answer: Inhibit 50S subunit of ribosomes
Explanation:Erythromycin is a bacteriostatic antibiotic. This means it stops the further growth of bacteria rather than directly destroying it. This is achieved by inhibiting protein synthesis. Erythromycin binds to the 23S ribosomal RNA molecule in the 50S subunit of the bacterial ribosome. This causes a blockage in the exiting of the peptide chain that is growing. Given that humans have 40S and 60S subunits, and do not have 50S subunits, erythromycin does not affect protein synthesis in human tissues.
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This question is part of the following fields:
- Clinical Sciences
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Question 15
Incorrect
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A study is developed to look at the potential of hip protectors to reduce femoral neck fractures in elderly nursing home patients. The study included 800 patients randomly selected with an average age of 82 years of age. The data was collected over a two year period and the patients were randomly put in the standard care group or the hip protector group. From the 400 patients assigned to the hip protector group, 10 had a femoral neck fracture over the two year period. From the 400 patients assigned to the standard care group, 20 had a femoral neck fracture over the two year period. What is the correct value regarding the absolute risk reduction?
Your Answer:
Correct Answer: 0.025
Explanation:Absolute risk reduction (ARR) – also called risk difference (RD) – is the most useful way of presenting research results to help your decision-making. In this example, the ARR is 8 per cent (20 per cent – 12 per cent = 8 per cent). This means that, if 100 children were treated, 8 would be prevented from developing bad outcomes. Another way of expressing this is the number needed to treat (NNT). If 8 children out of 100 benefit from treatment, the NNT for one child to benefit is about 13 (100 ÷ 8 = 12.5). CER = 20 / 400 = 1 / 20 = 0.05, EER = 10 / 400 = 0.025, ARR =CER – EER = 0.025
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This question is part of the following fields:
- Clinical Sciences
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Question 16
Incorrect
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You want to measure the potential benefit of creating a service dedicated to patients with multiple sclerosis in the local area. Which factor would determine how many resources will be required?
Your Answer:
Correct Answer: Prevalence
Explanation:To describe how often a disease or another health event occurs in a population, different measures of disease frequency can be used. The prevalence reflects the number of existing cases of a disease. In contrast to the prevalence, the incidence reflects the number of new cases of disease and can be reported as a risk or as an incidence rate. Prevalence and incidence are used for different purposes and to answer different research questions.
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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 is true regarding Escherichia coli infection?
Your Answer:
Correct Answer: E coli is an important cause of neonatal meningitis
Explanation:Escherichia coli (also known as E. coli) is a gram-negative, facultatively anaerobic, rod-shaped bacterium commonly found in the lower intestine of warm-blooded organisms. Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in their hosts, and are occasionally responsible for product recalls due to food contamination. The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2, and preventing colonization of the intestine with pathogenic bacteria. Virulent strains can cause gastroenteritis, urinary tract infections, and neonatal meningitis.
The most common causes of neonatal meningitis is bacterial infection of the blood, known as bacteremia (specifically Group B Streptococci (GBS; Streptococcus agalactiae), Escherichia coli, and Listeria monocytogenes). Although there is a low mortality rate in developed countries, there is a 50% prevalence rate of neurodevelopmental disabilities in E. coli and GBS meningitis -
This question is part of the following fields:
- Clinical Sciences
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Question 18
Incorrect
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Choose the correct statement regarding endothelin:
Your Answer:
Correct Answer: Endothelin antagonists are useful in primary pulmonary hypertension
Explanation:Current guidelines recommend the use of ambrisentan, Bosentan (recommendation I, level of evidence A) and macitentan (I, B) in patients with PAH and WHO functional class II and III. In WHO functional class IV, the first-line drug is Epoprostenol and the recommendation for Endothelin receptor antagonists is weaker (IIb, C).
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This question is part of the following fields:
- Clinical Sciences
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Question 19
Incorrect
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Which of following does not promote the release of endothelin?
Your Answer:
Correct Answer: Prostacyclin
Explanation:Prostacyclin (PGI2) generated by the vascular wall is a potent vasodilator, and the most potent endogenous inhibitor of platelet aggregation so far discovered. Prostacyclin inhibits platelet aggregation by increasing cyclic AMP levels. Prostacyclin is a circulating hormone continually released by the lungs into the arterial circulation. Circulating platelets are, therefore, subjected constantly to prostacyclin stimulation and it is via this mechanism that platelet aggregability in vivo is controlled.
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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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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 21
Incorrect
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A cohort study is being designed to look at the relationship between smoking and prostate cancer. What is the usual outcome measure in a cohort study?
Your Answer:
Correct Answer: Relative risk
Explanation:A cohort study is a particular form of longitudinal study that samples a cohort (a group of people who share a defining characteristic, typically those who experienced a common event in a selected period, such as birth or graduation), performing a cross-section at intervals through time.
The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. Relative risk is used in the statistical analysis of the data of experimental, cohort and cross-sectional studies, to estimate the strength of the association between treatments or risk factors, and outcomes. -
This question is part of the following fields:
- Clinical Sciences
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Question 22
Incorrect
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Each one of the following statements regarding atrial natriuretic peptide are true, except:
Your Answer:
Correct Answer: Secreted mainly by the left atrium
Explanation:Atrial natriuretic peptide (ANP) is a 28-amino acid peptide that is synthesized, stored, and released by atrial myocytes in response to atrial distension, angiotensin II stimulation, endothelin, and sympathetic stimulation (beta-adrenoceptor mediated). ANP is synthesized and secreted by cardiac muscle cells in the walls of the atria in the heart. The main physiological actions of natriuretic peptides is to reduce arterial pressure by decreasing blood volume and systemic vascular resistance. It causes a reduction in expanded extracellular fluid (ECF) volume by increasing renal sodium excretion.
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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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Primarily, funnel plots are used to do what?
Your Answer:
Correct Answer: Demonstrate the existence of publication bias in meta-analyses
Explanation:Funnel plots are graphical tools to assess and compare clinical performance of a group of care professionals or care institutions on a quality indicator against a benchmark. Incorrect construction of funnel plots may lead to erroneous assessment and incorrect decisions potentially with severe consequences.
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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 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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Question 25
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 26
Incorrect
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A case-control study is developed to assess passive smoking as a risk factor for the development of asthma in children. The total number of patients recruited for this study is 200. 40 out of the 200 patients report at least one parent smoking in the house when they were younger. 200 more people without asthma are recruited and 20 out of them report that at least one parent smoked in the house when they were younger. What is the odds ratio of patients with asthma having been exposed to passive smoking during their childhood?
Your Answer:
Correct Answer: 2.25
Explanation:An odds ratio (OR) is a measure of association between an exposure and an outcome. The OR represents the odds that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. Odds ratios are most commonly used in case-control studies, however they can also be used in cross-sectional and cohort study designs as well (with some modifications and/or assumptions). Where
a = Number of exposed cases
b = Number of exposed non-cases
c = Number of unexposed cases
d = Number of unexposed non-cases
OR=(a/c) / (b/d) = ad/bc
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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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Which of the following phases determines the length of the cell cycle?
Your Answer:
Correct Answer: G1
Explanation:The duration of these cell cycle phases varies considerably in different kinds of cells. For a typical rapidly proliferating human cell with a total cycle time of 24 hours, the G1 phase might last about 11 hours, S phase about 8 hours, G2 about 4 hours, and M about 1 hour. The proliferation of most animal cells is similarly regulated in the G1 phase of the cell cycle. In particular, a decision point in late G1, called the restriction point in animal cells, is the point at which the cell becomes committed to the cell cycle and after which extracellular proliferation stimulants are no longer required.. Although the proliferation of most cells is regulated primarily in G1, some cell cycles are instead controlled principally in G2.
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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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Which one of the following statements regarding nitric oxide is incorrect?
Your Answer:
Correct Answer: Promotes platelet aggregation
Explanation:Nitric oxide, known as an endothelium-derived relaxing factor (EDRF), is biosynthesized endogenously from L-arginine, oxygen, and NADPH by various nitric oxide synthase (NOS) enzymes and is a signaling molecule in many physiological and pathological processes in humans.
One of the main enzymatic targets of nitric oxide is guanylyl cyclase. The binding of nitric oxide to the haem region of the enzyme leads to activation, in the presence of iron. -
This question is part of the following fields:
- Clinical Sciences
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Question 29
Incorrect
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Cholecystokinin is secreted from:
Your Answer:
Correct Answer: I cells in upper small intestine
Explanation:Cholecystokinin (CCK) was discovered in 1928 in jejunal extracts as a gallbladder contraction factor. It was later shown to be member of a peptide family, which are all ligands for the CCK1 and CCK2 receptors. CCK peptides are known to be synthetized in the small intestinal endocrine I-cells and cerebral neurons.
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This question is part of the following fields:
- Clinical Sciences
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Question 30
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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SESSION STATS - PERFORMANCE PER SPECIALTY
