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Question 1
Incorrect
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A 20-year-old man in India is attacked by a wild dog and subsequently shows symptoms of rabies, including irritability, drooling, and seizures. The virus responsible for rabies is a rhabdovirus, which uses RNA polymerase to create a complementary RNA strand from a single strand of RNA. This newly-synthesised strand then acts as messenger-RNA (mRNA). What is the best description of the rhabdovirus genome?
Your Answer: Single stranded DNA (ssDNA)
Correct Answer: Negative-sense RNA (−RNA)
Explanation:Virus Classification Based on Genome
Viruses are categorized based on their genome, which can either be DNA or RNA. The RNA or DNA can be single or double-stranded. The genome of a virus determines its classification. The rhabdovirus, for instance, contains a single strand of RNA initially, which means that the first, second, and last answer options cannot be correct.
Positive-sense RNA viruses, such as picornavirus, flavivirus, coronavirus, and calicivirus, use the RNA strand directly as mRNA. On the other hand, negative-sense RNA viruses require RNA polymerase to copy the RNA strand and generate a complementary RNA strand, which then acts as mRNA. The rhabdovirus falls under this category. virus classification based on genome is crucial in developing effective treatments and vaccines.
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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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A study investigated the effectiveness of a new statin therapy in preventing ischaemic heart disease in a diabetic population aged 60 and above. Over a period of five years, 1000 patients were randomly assigned to receive the new therapy and 1000 were given a placebo. The results showed that there were 150 myocardial infarcts (MI) in the placebo group and 100 in the group treated with the new statin. What is the number needed to treat to prevent one MI during the study period?
Your Answer: 40
Correct Answer: 20
Explanation:The Glycaemic Index Method is a commonly used tool by dieticians and patients to determine the impact of different foods on blood glucose levels. This method involves calculating the area under a curve that shows the rise in blood glucose after consuming a test portion of food containing 50 grams of carbohydrate. The rationale behind using the GI index is that foods that cause a rapid and significant increase in blood glucose levels can lead to an increase in insulin production. This can put individuals at a higher risk of hyperinsulinaemia and weight gain.
High GI foods are typically those that contain refined sugars and processed cereals, such as white bread and white rice. These foods can cause a rapid increase in blood glucose levels, leading to a surge in insulin production. On the other hand, low GI foods, such as vegetables, legumes, and beans, are less likely to cause a significant increase in blood glucose levels.
Overall, the Glycaemic Index Method can be helpful in making informed food choices and managing blood glucose levels. By choosing low GI foods, individuals can reduce their risk of hyperinsulinaemia and weight gain, while still enjoying a healthy and balanced diet.
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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 65-year-old man visits the clinic with a complaint of experiencing blue vision. He has started taking a high dose of Viagra to treat his erectile dysfunction, and you suspect that this medication may be the reason behind his visual changes. Which enzyme inhibition is primarily responsible for this side effect?
Your Answer:
Correct Answer: PDE-6
Explanation:The Role of Phosphodiesterase-6 in Vision and the Side Effects of Viagra
Phosphodiesterase-6 plays a crucial role in the transmission of visual signals from rod cells in the retina to electrical signals in the brain. This enzyme is activated by changes in rhodopsin, which occur in response to exposure to light. However, high doses of Viagra, which is an inhibitor of PDE-5, can also inhibit PDE-6, leading to side effects such as blue vision. Patients may choose to reduce their dosage or tolerate these side effects in exchange for the improved sexual function that Viagra provides.
Overall, the role of PDE-6 in vision and the potential side effects of Viagra is important for both medical professionals and patients. By weighing the benefits and risks of this medication, individuals can make informed decisions about their sexual health and overall well-being.
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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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Following a meal, what is the primary body tissue where glycogen production occurs?
Your Answer:
Correct Answer: Liver
Explanation:Glycogen Production and Structure
The liver and muscle are the primary sites of glycogen production, which serves as a storage reservoir for excess glucose. In muscle, glycogen provides a readily available source of energy to support muscle contraction and exertion. The process of glycogen formation involves the conversion of glucose into glucose-6-phosphate and glucose-1-phosphate, which are then attached to a larger molecule called UDP. This provides a platform for glucose to be added onto the glycogen polymer in straight chains through an α1-4 glycosidic linkage. Once a chain reaches around 11 residues long, a branching enzyme removes a 6-8 unit fragment to create a new branch. The highly branched structure of glycogen allows for the storage of a large amount of glucose in a relatively small area. The diagram of glycogen structure illustrates its composition of glucose chains linked by α1-4 glycosidic linkage and branch points linked by α1-6 glycosidic linkage.
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This question is part of the following fields:
- Clinical Sciences
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Question 5
Incorrect
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A 25-year-old farmer injures his hand on barbed wire and visits his GP after four days with a painful wound. The wound is swollen, tender, and hot to the touch. Which chemical mediator is responsible for increasing vascular permeability during acute inflammation?
Your Answer:
Correct Answer: Leukotrienes C4, D4, E4 (LTC4, D4, E4)
Explanation:Increased vascular permeability is a key aspect of acute inflammation, caused by chemical mediators such as histamine, serotonin, complement components C3a and C5a, leukotrienes, oxygen free radicals, and PAF. LTB4 causes chemotaxis of neutrophils, TNF causes fever, and glycine is an inhibitory neurotransmitter that does not affect vascular permeability.
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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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Which type of lipoprotein is involved in the development of atherosclerosis observed in coronary artery disease?
Your Answer:
Correct Answer: Low density lipoprotein (LDL)
Explanation:Atherosclerosis: The Gradual Narrowing of Arteries
Atherosclerosis is a gradual process that involves the narrowing of arteries due to the accumulation of lipid-rich deposits within artery walls. This condition can take many years to develop and is the primary cause of coronary heart disease, peripheral vascular disease, and ischemic stroke. When a clot forms over an atherosclerotic plaque, it can lead to a heart attack by blocking blood flow to the cardiac muscle.
Monocytes from the blood absorb oxidized LDL particles to form lipid-laden foam cells, which accumulate in the vessel walls and eventually form fatty streaks and atherosclerotic plaques. These foam cells secrete cytokines and chemokines that promote smooth muscle cell proliferation, contributing to the development of the atherosclerotic plaque. Any damage to the plaque can result in the release of tissue factor, which promotes clot formation.
LDL can easily form oxidized LDL, especially in the presence of haem, which is released from damaged red blood cells in areas of turbulent blood flow. Inflammation, obesity, diabetes, and impaired glucose tolerance can also contribute to the formation of oxidized LDL. the causes and mechanisms of atherosclerosis is crucial in preventing and treating this condition.
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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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Can you provide a definition for pseudostratified epithelium?
Your Answer:
Correct Answer: A single layer of epithelial cells with nuclei at different height
Explanation:Types of Epithelial Tissue
Epithelial tissue is a type of tissue that lines the surfaces of organs, glands, and body cavities. There are different types of epithelial tissue, including simple, stratified, and transitional epithelium. Pseudostratified epithelium is a type of simple epithelium that appears to be several cells deep due to the nuclei being at different heights. This gives the illusion of a stratified epithelium. The lining of the conducting airways, up to the respiratory bronchioles, is lined by ciliated, pseudostratified columnar epithelium.
A simple epithelium is a single layer of epithelial cells with nuclei at the same height, while a stratified epithelium is multiple layers of epithelial cells upon each other, usually stratified squamous. The skin is an example of a stratified epithelium. A transitional epithelium is multiple layers of epithelial cells that stretch over each other. This type of epithelium is found in the ureters and bladder. When contracted, the epithelium is stratified, but when stretched, the epithelial cells slide to give a simple epithelium. This allows for expansion with a minimal increase in wall pressure.
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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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Which of the following tissues does not have considerable levels of AST and is therefore not used as a marker of liver hepatocellular damage?
Your Answer:
Correct Answer: Testes
Explanation:AST and ALT as Markers of Liver Function
AST and ALT are enzymes that are commonly used as markers of liver function. AST is found in metabolically active tissues such as muscle, heart, liver, kidney, and brain, while ALT is mainly found in the liver with very low levels elsewhere. However, because of its wide distribution, AST is not specific as a marker of liver disease. It can also be elevated in myocardial infarction, myositis, and other conditions. Therefore, many laboratories now use ALT preferentially as a more specific test for liver dysfunction.
It is important to note that neither AST nor ALT test the true ‘function’ of the liver. They merely represent markers of hepatocyte disruption or damage. For a better measure of the synthetic function of the liver, the prothrombin time (PT) or INR is used as it produces coagulation factors. It is crucial to interpret the results of AST and ALT tests with caution and in conjunction with other liver function tests to accurately diagnose liver disease.
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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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What respiratory disorder is identified by the existence of Curschmann's spirals and Charcot-Leyden crystals?
Your Answer:
Correct Answer: Asthma
Explanation:Respiratory Pathologies and Their Pathological Features
Asthma is a respiratory pathology that is characterized by an excessive inflammatory response of the small bronchial airways to harmless stimuli. This response involves the infiltration of eosinophils, which can aggregate and form Charcot-Leyden crystals. The accumulation of mucus in the airways can lead to the formation of Curschmann spirals. Bronchiectasis is another respiratory pathology that involves the progressive dilation of the small airways. COPD shares similar features with chronic asthma, but with more marked smooth muscle hyperplasia. Cystic fibrosis has pathological features similar to bronchiectasis, but it predominantly affects the upper lobes. Pulmonary fibrosis is a pathological term for the deposition of excess connective and fibrous tissue in the pulmonary interstitial space. Although there are multiple causes, the underlying pathology is the same.
In summary, respiratory pathologies can have different pathological features, but they all involve some form of inflammation or structural damage to the airways. Asthma, bronchiectasis, COPD, cystic fibrosis, and pulmonary fibrosis are some of the most common respiratory pathologies. their underlying pathology is crucial for developing effective treatments and improving patient outcomes.
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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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You are invited to witness a lumbar puncture on a 32-year-old male.
At what level of the vertebrae does the spinal cord typically terminate?Your Answer:
Correct Answer: L2
Explanation:The Importance of Knowing the Termination of the Spinal Cord
In most adults, the spinal cord ends at the level of L1/L2, while the cauda equina continues downwards within the vertebral column. However, there is some variation in adults, and in children, the spinal cord may extend as far as L3. It is crucial to be aware of this variation because trauma to the spinal cord during lumbar puncture can result in significant paralysis.
Moreover, identifying the interspace L3/4 using Tuffier’s line, which is drawn between both iliac crests, is highly inaccurate. This inaccuracy can lead to an inadvertent high lumbar puncture, which can cause complications. Therefore, it is essential to have a clear of the termination of the spinal cord to avoid any potential harm during medical procedures.
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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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To evaluate the effectiveness of a home cholesterol testing kit, a group of 500 individuals under the age of 40 were recruited. Each participant provided a blood sample for analysis. The results showed that 480 individuals had normal cholesterol levels and 20 individuals had high cholesterol levels. What is the sensitivity of the test?
Your Answer:
Correct Answer: 98%
Explanation:Specificity in Medical Testing
Specificity is a crucial concept in medical testing that refers to the accuracy of a test in identifying individuals who do not have a particular condition. In simpler terms, it measures the proportion of people who are correctly identified as not having the condition by the test. For instance, if a test has a specificity of 98%, it means that 98 out of 100 people who do not have the condition will be correctly identified as negative by the test.
To calculate specificity, we use the formula: Specificity = True Negative / (False Positive + True Negative). This means that we divide the number of true negatives (people who do not have the condition and are correctly identified as negative) by the sum of false positives (people who do not have the condition but are incorrectly identified as positive) and true negatives.
It is important to note that highly specific tests are useful for ruling conditions in, which means that if the test is positive, the person is very likely to have the disease. However, it is rare to find tests with 100% sensitivity and/or specificity, including pregnancy tests. Therefore, it is crucial to interpret test results in conjunction with other clinical information and to consult with a healthcare professional for proper diagnosis and treatment.
In summary, specificity is essential in medical testing as it helps to determine the accuracy of a test in identifying individuals who do not have a particular condition. By using the formula and interpreting test results in conjunction with other clinical information, healthcare professionals can make informed decisions about diagnosis and treatment.
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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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A 35-year-old man arrives at the emergency department with chest pain. He confesses to using cocaine. Upon examination, his heart rate is 110 bpm and his blood pressure is 118/76 mmHg. An ECG reveals T wave inversion in leads V3-V6. What part of his heart has been impacted?
Your Answer:
Correct Answer: Anterolateral
Explanation:ECG Leads and Myocardial Infarction
The T wave inversion on an electrocardiogram (ECG) can indicate a non-ST elevation myocardial infarction (MI) caused by cocaine abuse. The ECG has different leads that correspond to different areas of the heart. The septal leads are V1-V2, the anterior leads are V3-V4, the lateral leads are V5-V6, I, and aVL, and the inferior leads are II, III, and aVF. However, detecting posterior infarcts on a 12-lead ECG can be challenging. Some medical centers use additional ECG leads V7-9 to help identify posterior infarcts.
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This question is part of the following fields:
- Clinical Sciences
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Question 13
Incorrect
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Which muscles are responsible for flexing the hip joint?
Your Answer:
Correct Answer: Psoas
Explanation:Muscles and their Functions in Joint Movement
The hip joint has three main flexors, namely the iliacus, psoas, and rectus femoris muscles. These muscles are responsible for flexing the hip joint, which is the movement of bringing the thigh towards the abdomen. On the other hand, the gluteus maximus and medius muscles are involved in hip extension, which is the movement of bringing the thigh backward.
Moving on to the elbow joint, the bicep femoris muscle is one of the primary flexors. This muscle is responsible for bending the elbow, which is the movement of bringing the forearm towards the upper arm. Lastly, the adductor brevis muscle is responsible for adducting the leg at the hip joint, which is the movement of bringing the leg towards the midline of the body.
In summary, muscles play a crucial role in joint movement. the functions of these muscles can help in identifying and addressing issues related to joint movement and mobility.
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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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What is the intracellular pathway that is triggered by NK cells and CD8+ T cells in infected cells to induce apoptosis?
Your Answer:
Correct Answer: Caspase system
Explanation:Mechanisms of Cell Killing and Metabolic Pathways
NK cells and cytotoxic T cells have two ways of killing virally infected cells. The first way is through the release of perforin and granzyme, which creates small holes in the membrane of the target cell, allowing entry of granzyme. Granzyme then activates the caspase cascade, resulting in apoptosis. The second way is through ligation of Fas-receptors, which triggers the caspase cascade, also resulting in apoptosis.
The pentose phosphate pathway is a metabolic pathway that produces NADPH and riboses, which are 5-carbon sugars. This pathway is involved in the production of energy and biosynthetic precursors for the cell.
The PI3K pathway is an intracellular signaling pathway that is used by some growth-related factors, such as insulin. This pathway plays a crucial role in regulating cell growth, proliferation, and survival.
The protein C cascade is a natural antithrombotic mechanism that helps prevent blood clots from forming. This cascade is activated when there is damage to the blood vessel wall, and it helps to break down blood clots that have already formed.
The Ras-kinase pathway is the main pro-growth pathway that is activated by growth factors. This pathway plays a crucial role in regulating cell growth, proliferation, and differentiation. It is involved in many cellular processes, including cell cycle progression, cell survival, and cell migration.
Overall, these mechanisms and pathways play important roles in maintaining the health and function of cells in the body.
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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 65-year-old African American woman has been diagnosed with iodine deficiency.
What are the primary clinical manifestations of iodine deficiency?Your Answer:
Correct Answer: Impaired memory and concentration
Explanation:The Importance of Iodine in the Diet
Iodine is a crucial mineral that is necessary for the proper functioning of the body. Unfortunately, it is also one of the most common nutrient deficiencies worldwide. This deficiency can lead to a variety of iodine-related disorders, which are considered one of the most common preventable causes of mental incapacity.
One of the primary functions of iodine is the production of thyroid hormones, which are essential for all body cells. These hormones are particularly important for the development of the fetal brain, and a lack of thyroid hormones at this stage can lead to devastating and irreversible effects. Iodine deficiency commonly causes goitre, and the clinical effects are comparable to profound hypothyroidism.
The effects of iodine deficiency can be severe and long-lasting. In utero, it can lead to impaired cognitive function, deafness, and motor defects, a condition known as cretinism. In children and adolescents, it can cause cognitive impairment and poor growth. In adults, it can lead to confusion, poor concentration, and goitre.
Iodine is abundant in the sea, but inland areas are more at risk of iodine deficiency. If the soil is iodine deficient, all plants that grow on it, and livestock that feed upon them, will also be iodine deficient. It is essential to ensure that the diet contains sufficient iodine to prevent these devastating effects.
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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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What medication enhances the body's metabolic rate?
Your Answer:
Correct Answer: Thyroxine
Explanation:Medications and Their Effects on Metabolic Rate
Medications can have varying effects on the body’s metabolic rate. Some medications are known to decrease metabolic rate, such as sedatives, beta blockers like propranolol, sulphonylureas used to treat diabetes, and certain chemotherapy agents. These medications can slow down the body’s processes and lead to a decrease in energy expenditure.
On the other hand, there are medications that can increase metabolic rate. Thyroxine, a hormone produced by the thyroid gland, is known to increase metabolic rate. Recombinant human growth hormone, which is used to treat growth hormone deficiency, can also increase metabolic rate. These medications can speed up the body’s processes and lead to an increase in energy expenditure.
It is important to note that the effects of medications on metabolic rate can vary from person to person and may depend on factors such as dosage and individual health conditions. It is always recommended to consult with a healthcare provider before starting or stopping any medication.
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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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In which section of the digestive system are Brunner's glands located?
Your Answer:
Correct Answer: Duodenum
Explanation:Glands and Structures of the Digestive System
The digestive system is composed of various glands and structures that play important roles in the digestion and absorption of nutrients. One of these structures is the Brunner’s glands, which are coiled glands found in the submucosa of the duodenum. These glands produce an alkaline fluid that helps neutralize the acidic contents of the stomach as they enter the small intestine.
In contrast, salivary glands are typical exocrine glands that are composed of acini and ducts. These glands produce saliva, which contains enzymes that begin the process of breaking down carbohydrates in the mouth.
The stomach has deep pits that contain different cell types, including endocrine cells and goblet cells. These cells secrete various substances that aid in digestion and protect the stomach lining from the corrosive effects of gastric acid.
The jejunum and ileum are parts of the small intestine that have villi, which are finger-like projections that increase the surface area for absorption. At the base of the villi are the crypts of Lieberkuhn, where new enterocytes are produced and migrate up to the tip of the villi. These enterocytes are responsible for absorbing nutrients from the digested food.
Overall, the digestive system is a complex network of glands and structures that work together to ensure the proper digestion and absorption of nutrients from the food we eat.
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This question is part of the following fields:
- Clinical Sciences
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Question 18
Incorrect
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What muscles are responsible for dorsiflexion of the ankle joint?
Your Answer:
Correct Answer: Tibialis anterior
Explanation:Muscles Involved in Ankle and Toe Movements
The tibialis anterior muscle is responsible for dorsiflexion of the ankle joint, which means it helps lift the foot upwards towards the shin. On the other hand, the tibialis posterior, soleus, and gastrocnemius muscles are involved in plantar flexion, which is the movement of pointing the foot downwards. These muscles work together to push the foot off the ground during walking or running.
Another muscle involved in foot movement is the flexor digitorum longus, which is responsible for flexion of the second to fifth toes. This muscle helps curl the toes downwards towards the sole of the foot. All of these muscles play important roles in the complex movements of the foot and ankle, allowing us to walk, run, jump, and perform other activities that require precise control of our lower limbs.
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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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A 58-year-old patient presents to the clinic with a chief complaint of reduced night vision. Upon further examination, it is discovered that the patient has a medical history of pancreatic insufficiency, chronic diarrhea, and malabsorption. Can you identify which vitamin deficiency is commonly linked to issues with night vision?
Your Answer:
Correct Answer: Vitamin A
Explanation:The Role of Vitamin A in Night Vision
Vitamin A is essential for the production of rhodopsin, a protein found in the retina that is responsible for converting light into energy. This process involves the conversion of vitamin A into 11-cis retinal or all-trans retinol, which is stored in the pigment layer of the retina. Isomerase is an enzyme that plays a crucial role in the production of 11-cis retinal, which is then used to produce rhodopsin.
A deficiency in vitamin A can lead to a problem with night vision, as the body is unable to produce enough rhodopsin to respond to changes in light. This can result in difficulty seeing in low light conditions, such as when driving at night or in dimly lit environments. It is important to ensure that the body receives an adequate amount of vitamin A through a balanced diet or supplements to maintain healthy vision.
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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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An 80-year-old woman complains of altered bowel movements and a sigmoidoscopy reveals an abnormal, ulcerated mass in the sigmoid colon. She undergoes anterior resection. Upon pathological examination, it is found that the tumor has invaded the muscularis propria but not the underlying tissues. Out of 36 lymph nodes, two are positive. What is the Dukes stage of this tumor?
Your Answer:
Correct Answer: C
Explanation:Staging Colorectal Cancer: Dukes System
Colorectal cancer can be staged using either the TNM classification system or the simpler Dukes system. Both methods are used to determine the appropriate treatment and prognosis for the patient. The Dukes system categorizes the cancer into four stages based on the extent of its spread.
Stage A refers to cancer that is confined to the mucosa or submucosa only, with a 93% 5-year survival rate. Stage B indicates that the cancer has invaded into the muscularis propria but has not spread beyond it, with a 77% 5-year survival rate. Stage C is characterized by the presence of local lymph node metastases, regardless of the depth of invasion, and has a 48% 5-year survival rate. Finally, Stage D indicates the presence of distant metastases, with a 6% 5-year survival rate. However, if the metastases are isolated to the liver, a 25-40% 5-year survival rate is possible.
In summary, the Dukes system provides a simple and effective way to stage colorectal cancer based on the extent of its spread. This information is crucial in determining the appropriate treatment and predicting the patient’s prognosis.
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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 45-year-old woman is currently being treated with lithium for bipolar depression. It is believed that the drug affects the phosphoinositide cycle, resulting in a decrease in both Km and Vmax. This can be observed on a Lineweaver-Burk plot, where the Y-intercept shifts upwards, the X-intercept shifts to the left, and the slope remains constant. What type of inhibition is being described in this situation?
Your Answer:
Correct Answer: Uncompetitive
Explanation:Types of Reversible Enzyme Inhibition
There are three types of reversible enzyme inhibition: competitive, non-competitive, and uncompetitive. Competitive inhibitors are similar in structure to the substrate and compete for the active site of the enzyme. This results in an increase in Km, but Vmax remains unchanged. Non-competitive inhibitors bind to a different site on the enzyme and do not resemble the substrate. This causes a decrease in Vmax, but Km remains unchanged. Uncompetitive inhibitors bind to the enzyme-substrate complex and render the enzyme inactive, leading to a decrease in both Km and Vmax. On a Lineweaver-Burk plot, the slope increases for competitive and non-competitive inhibitors, but remains the same for uncompetitive inhibitors. The Y-intercept shifts upwards for non-competitive inhibitors, but remains unchanged for competitive and uncompetitive inhibitors. The X-intercept shifts to the right for competitive inhibitors, but remains unchanged for non-competitive and uncompetitive inhibitors. It is important to note that irreversible inhibitors covalently bind to the enzyme and permanently inactivate it, causing the same kinetic effects as non-competitive inhibitors. Dilution is not a mechanism of enzyme inhibition.
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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 random selection of 800 elderly adults agree to participate in a study of the possible effects of drug Y.
They are followed prospectively for a period of ten years to see if there is an association between the incidence of dementia and the use of drug Y.
Which type of study is described here?Your Answer:
Correct Answer: Cohort study
Explanation:Different Types of Research Studies
Cohort studies, also known as longitudinal studies, involve the follow-up of individuals over a defined period of time. These studies can be either prospective or historical. In a prospective cohort study, individuals who are exposed and not exposed to a potential risk factor are followed up, and their disease experience is compared at the end of the follow-up period. On the other hand, a historical cohort study identifies a cohort for whom records of exposure status are available from the past, and their disease experience is measured after a substantial period of time has elapsed since exposure.
In contrast, a case-control study compares patients who have a disease with those who do not have the disease and looks retrospectively at their exposure to risk factors. A cross-over study is similar to a longitudinal study, but the interventions given to each group are crossed over at a set time in the trial design. Finally, a cross-sectional study analyzes data at a certain point in time of a specific population.
Among these types of research studies, randomized controlled clinical trials are considered one of the best for statistical significance. the different types of research studies is crucial in designing and conducting studies that can provide reliable and valid results.
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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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A study recruits a random sample of 5,000 individuals over the age of 50 and asks about their use of herbs and other health supplements. Participants are then followed-up for five years. The study aims to compare the incidence of colon cancer among participants to see if the use of herbs or health supplements has any effect.
What type of study is this?Your Answer:
Correct Answer: Cohort study
Explanation:Different Types of Studies
When it comes to conducting research, it is important to understand the characteristics of different types of studies as they serve different purposes. For instance, a cohort study is typically used to investigate risk factors of diseases. On the other hand, a case-control study begins with identifying cases of a particular disease and controls who are not affected. Unlike a cohort study, a case-control study does not require waiting for the occurrence of the disease.
Qualitative studies, on the other hand, are used to explore variables that are not easily quantifiable, such as opinions and thoughts of patients. These studies are not suitable for studying the incidence and risk of diseases. Lastly, a randomized controlled trial involves researchers assigning treatment instead of participants choosing their own treatment.
In summary, the characteristics of different types of studies is crucial in selecting the appropriate research method for a particular research question.
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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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A 42-year-old patient is exhibiting symptoms of pellagra. What is the underlying cause of this condition?
Your Answer:
Correct Answer: Vitamin B3 deficiency
Explanation:Pellagra: A Vitamin B3 Deficiency
Pellagra is a condition caused by a lack of vitamin B3 (niacin) in the body. It is characterized by various symptoms, including skin changes on sun-exposed areas, an inflamed and swollen tongue, reduced appetite, gastrointestinal upset, anxiety, insomnia, confusion, and in severe cases, hallucinations, paranoia, and severe depression. Niacin can be obtained from the diet through nicotinamide or nicotinic acid, and the body can also produce it from tryptophan found in dietary protein. Good dietary sources of niacin include liver, chicken, nuts, tuna, and white fish. However, the body has limited capacity to store niacin, and symptoms of deficiency can appear within a few weeks.
Niacin deficiency is rare and is associated with low protein diets, malabsorption disorders such as coeliac disease and Crohn’s disease, and heavy alcohol consumption. Additionally, a deficiency of riboflavin and pyridoxine can reduce the body’s ability to produce niacin from tryptophan. It is important to maintain a balanced diet to prevent the development of pellagra and other vitamin deficiencies.
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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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A woman in her 30s presents with an elevated alkaline phosphatase (ALP) level during pregnancy. All other liver function tests are within normal range and she reports feeling well. What is the probable cause of this finding?
Your Answer:
Correct Answer: Placental production of ALP
Explanation:Alkaline Phosphatase and Its Causes
Alkaline phosphatase is an enzyme that can be found in various tissues in the body, making it a common part of liver function tests. An elevated level of ALP can be caused by different factors, including isoenzymes from the liver or bone, as well as the placenta in pregnant women. In children, elevated ALP levels are usually physiological and signify bone growth. However, transient hyperphosphatasia of infancy can cause a more dramatic increase in ALP, which is benign and resolves after a few months.
Liver disease can also cause an increase in ALP, particularly with hepatobiliary obstruction, such as pancreatic carcinoma or a gallstone in the common bile duct. When bile drainage is obstructed, ALP synthesis increases significantly. On the other hand, liver diseases that predominantly cause hepatocellular damage will cause a lesser degree of ALP elevation.
ALP also aids in the calcification process in bone and is found in osteoblasts. Therefore, any disease affecting bone turnover and calcification, including Paget’s disease, vitamin D deficiency, primary and secondary hyperparathyroidism, bone malignancies, and fracture healing, can cause abnormal ALP levels. Paget’s disease, which involves increased bone turnover, is a relatively common finding in older patients and can cause various symptoms such as tender bone/skull overgrowth, sensorineural deafness, pathological fractures, and rarely, high output cardiac failure.
In summary, the causes of elevated ALP levels can help in diagnosing and managing various conditions affecting the liver and bone.
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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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A neonatal hearing screening program screened 10,000 newborns using otoacoustic emissions (OAE), which has a sensitivity of 80%. Out of the screened subjects, 200 failed the test and were invited for a brainstem auditory evoked potential (BAEP) test, which is the gold standard for diagnosing hearing impairment in newborns. The BAEP test confirmed that 100 of the 200 subjects had hearing impairment. What is the correct statement regarding this scenario?
Your Answer:
Correct Answer: If the prevalence of hearing impairment increases, the positive predictive value of OAE will increase
Explanation:The Impact of Disease Prevalence on Screening Test Results
Screening tests are commonly used to detect the presence of a disease in a population. The accuracy of a screening test is typically measured by its sensitivity and specificity, which are not significantly affected by the prevalence of the disease. However, the positive predictive value (PPV) and negative predictive value (NPV) of a screening test can be influenced by disease prevalence.
When the prevalence of a disease increases, the PPV of a screening test will also increase. This means that a positive test result is more likely to be a true positive when the disease is more common in the population. On the other hand, the NPV of a screening test will decrease as disease prevalence increases. This means that a negative test result is less likely to be a true negative when the disease is more prevalent.
Therefore, it is important to consider disease prevalence when interpreting the results of a screening test. A high PPV indicates a greater likelihood of disease presence, while a low NPV suggests a higher risk of false negatives. Healthcare professionals should take into account the prevalence of the disease in the population being screened to accurately interpret the results of a screening test.
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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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What is the substrate utilized for gluconeogenesis in humans?
Your Answer:
Correct Answer: Lactate
Explanation:Substrates for Gluconeogenesis
Gluconeogenesis is the process of creating glucose from non-carbohydrate sources. The main substrates used for gluconeogenesis include lactate, alanine, pyruvate, other amino acids, and glycerol. Lactate is produced in non-hepatic tissues, such as muscle during exercise, and can travel to the liver to be converted back into glucose. This process is known as the Cori cycle. Alanine can also be used as a substrate for gluconeogenesis, as it travels to the liver. Pyruvate, produced during anaerobic circumstances, can be converted into alanine by the enzyme alanine aminotransferase (ALT).
Almost all amino acids present in proteins, except for leucine and lysine, can be converted into intermediates of the Krebs cycle, allowing them to be used for gluconeogenesis. This is a crucial source of new glucose during prolonged fasting. Additionally, the glycerol backbone from dietary triglycerides can be used for gluconeogenesis. However, propionate has a minimal role in humans, despite being a major substrate for gluconeogenesis in animals. the substrates used for gluconeogenesis is important for how the body creates glucose from non-carbohydrate sources.
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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 55-year-old obese male patient complains of a painful and swollen big toe accompanied by a mild fever. Given his history of gout, it is suspected to be the underlying cause of his current symptoms. Which blood test is the most useful in confirming a diagnosis of gout?
Your Answer:
Correct Answer: Serum urate
Explanation:Diagnosing Gout: the Tests and Procedures
Gout is a condition that occurs when urate crystals accumulate in the joints, leading to an intense inflammatory response. While several blood tests can help rule out other conditions, the most specific test for gout is the measurement of serum urate levels. However, it’s important to note that gout can still be present even without hyperuricemia, especially during an acute attack. Chondrocalcinosis, a condition characterized by calcium pyrophosphate deposition, can also be mistaken for gout.
To definitively diagnose gout, a joint aspiration procedure is necessary. This involves extracting fluid from the affected joint and examining it under polarized microscopy. Urate crystals are needle-shaped and exhibit negative birefringence, which is a key characteristic of gout.
In summary, diagnosing gout requires a combination of blood tests and joint aspiration procedures. While serum urate levels are the most specific blood test for gout, joint aspiration is necessary to confirm the presence of urate crystals. By these tests and procedures, healthcare providers can accurately diagnose and treat gout, improving patient outcomes.
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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 known opiate-abuser in his mid-twenties is observed injecting a substance and subsequently collapsing on the street. He is immediately transported to the emergency department. What acid-base disturbance would be anticipated in this scenario?
Your Answer:
Correct Answer: Respiratory acidosis
Explanation:Opiate Injection and Respiratory Acidosis
When a person injects opiates, it can lead to respiratory depression. This means that the person’s breathing will slow down, causing an increase in carbon dioxide (CO2) levels in the body. As a result, the person may experience respiratory acidosis, which is a condition where the blood becomes too acidic due to the buildup of CO2. This can lead to symptoms such as confusion, drowsiness, and shortness of breath. It is important to seek medical attention immediately if someone is experiencing these symptoms after injecting opiates. Proper treatment can help prevent further complications and ensure a safe recovery.
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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 4-year-old girl is rushed to the emergency department by her father due to breathing difficulties. He suspects that she may have ingested a small toy while he was not looking.
Which of the following statements accurately describes the lower respiratory tract?Your Answer:
Correct Answer: The right main bronchus is more vertical than the left
Explanation:Anatomy of the Bronchial Tree
The trachea divides into two bronchi at the sternal angle, with the right bronchus being wider, shorter, and more vertical than the left. This anatomical difference makes it more likely for foreign objects to become lodged in the right bronchus. However, this difference only occurs after the age of one, so younger children are at equal risk for foreign body aspiration in either bronchus.
Each main bronchus further divides into lobar bronchi, with the left having two and the right having three. These lobar bronchi then give rise to tertiary or segmental bronchi, which supply a specific bronchopulmonary segment. These segments are anatomically and functionally separate from each other and can be removed without affecting the surrounding lung tissue.
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This question is part of the following fields:
- Clinical Sciences
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