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Question 1
Correct
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The thalamic nuclei that project over wide regions of the neocortex are:
Your Answer: Specific relay nuclei
Explanation:The thalamus is considered the relay station for sensory and motor stimuli. There are three basic types of thalamic nuclei: relay nuclei, association nuclei and non-specific nuclei. Relay nuclei receive very well defined inputs and project this signal to functionally distinct areas of the cerebral cortex. These include the nuclei that relay primary sensations and also the nuclei involved in feedback of cerebellar signals and basal gangliar output.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 2
Correct
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A 35 year old sales representative presents with severe pain going down her neck and right arm. She admits that this pain is worse on sitting and driving for long periods. Past history is significant for two previous road traffic accidents. Examination reveals weakness and sensory loss over C5/C6 nerve distribution. There is pain with neck movement and particularly extension. Which of the following investigations would be the most helpful in this case?
Your Answer: MRI scan of the cervical spinal cord
Explanation:Cervical radiculopathy is usually due to compression or injury to a nerve root by a herniated disc or degenerative changes. Levels C5 to T1 are the most commonly affected. It is usually, but not always, accompanied by cervical radicular pain, a sharp and shooting pain that travels from the neck and down the upper limb and may be severe. This needs to be differentiated from pain referred from the musculoskeletal (somatic) structures in the neck, which may be aching rather than sharp, and is more severe in the neck than in the upper limb. The neurological signs of cervical radiculopathy depend on the site of the lesion. The patient may have motor dysfunction, sensory deficits or alteration in tendon reflexes. While pain is a common presenting symptom, not all radiculopathies are painful (i.e. only motor deficits may be obvious). CT scanning cannot accurately demonstrate the commonest cause for cervical radiculopathy (disc herniation) without myelography, which requires hospital admission, lumbar puncture and the use of contrast. In patients with cervical radiculopathy, MRI is the imaging technique of choice for the detection of root compression by disc herniation and osteophytes. MRI allows the nerve roots to be directly visualised. Nerve conduction studies are also useful in determining the nerve roots that are involved.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 3
Incorrect
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The following are synthesized in the liver EXCEPT?
Your Answer: Antithrombin-iii
Correct Answer: Cholecystokinin
Explanation:The liver is responsible for the mainstay of protein metabolism, synthesis as well as degradation. It is also responsible for a large part of amino acid synthesis. The liver plays a role in the production of clotting factors as well as red blood cell production. Some of the proteins synthesized by the liver include coagulation factors I (fibrinogen), II (prothrombin), V, VII, VIII, IX, X, XI, XIII, as well as protein C, protein S and antithrombin. The liver is a major site of production for thrombopoietin, a glycoprotein hormone that regulates the production of platelets by the bone marrow. The liver also produces albumin, the most abundant protein in blood serum and angiotensinogen. Cholecystokinin, previously called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 4
Incorrect
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The spinal cord receive its blood supply from the following arteries except:
Your Answer: Radicular arteries
Correct Answer: Lateral spinal artery
Explanation:The spinal cord (SC) is supplied by the single anterior spinal artery which supplies the anterior two thirds of the SC and paired posterior spinal arteries supplying the posterior one third. Anastomoses between the spinal arteries supply the lateral column. These arteries originate near the cervico-occipital junction and therefore have a smaller calibre and often discontinue. Thus, they require reinforcement by segmental/radicular arteries which are branches of the ascending cervical artery, deep cervical artery, intercostal arteries, lumbar arteries and lateral sacral arteries
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This question is part of the following fields:
- Medicine
- Neurology
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Question 5
Correct
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The process by which depolarization of the muscle fiber initiates contraction is called?
Your Answer: Action potential
Explanation:This process is known as an action potential. Upon generation of an action potential when depolarization reaches threshold, it spreads throughout the muscle fiber, resulting in generation of an excitation-contraction coupling leading to contraction of the muscle.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 6
Correct
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The Cellular Theory of Ageing involves?
Your Answer: Loss of telomeres
Explanation:Cellular theories of aging propose that human aging is the result of cellular aging, whereby an increasing proportion of cells reach senescence, a terminal stage at which cells will cease to divide. This will limit the body’s ability to regenerate and to respond to injury or stress. Telomeres are bits of DNA on the ends of chromosomes that protect chromosomes from sticking to each other or tangling, which could cause DNA to abnormally function. As cells replicate, telomeres shorten at the end of chromosomes, and this process correlates to senescence or cellular aging.
Other theories include:
- The Free Radical Theory: Implicates the gradual accumulation of oxidative cellular damage as a fundamental driver of cellular aging. This theory has evolved over time to emphasize the role of free radical induced mitochondrial DNA (mtDNA) mutations and the accumulation of mtDNA deletions. Given the proximity of mtDNA to the electron transport chain, a primary producer of free radicals, it postulates that the mutations would promote mitochondrial dysfunction and concomitantly increase free radical production in a positive feedback loop. It is known that diet, lifestyle, drugs (e.g. tobacco and alcohol) and radiation etc., are all accelerators of free radical production within the body.
- Error theory: based on the idea that errors can occur in the transcription of the synthesis of DNA. These errors are perpetuated and eventually lead to systems that do not function at the optimum level. The organism’s aging and death are attributable to these events (Sonneborn, 1979).
- The Cross-Linking Theory: also referred to as the Glycosylation Theory of Aging. In this theory it is the binding of glucose (simple sugars) to protein, (a process that occurs under the presence of oxygen) that causes various problems. Once this binding has occurred the protein becomes impaired and is unable to perform as efficiently. Living a longer life is going to lead to the increased possibility of oxygen meeting glucose and protein and known cross-linking disorders include senile cataract and the appearance of tough, leathery and yellow skin.
- The Neuroendocrine Theory First proposed by Professor Vladimir Dilman and Ward Dean MD, this theory elaborates on wear and tear by focusing on the neuroendocrine system. This system is a complicated network of biochemicals that govern the release of hormones which are altered by the walnut sized gland called the hypothalamus located in the brain. The hypothalamus controls various chain-reactions to instruct other organs and glands to release their hormones etc. The hypothalamus also responds to the body hormone levels as a guide to the overall hormonal activity. But as we grow older the hypothalamus loses it precision regulatory ability and the receptors which uptake individual hormones become less sensitive to them. Accordingly, as we age the secretion of many hormones declines and their effectiveness (compared unit to unit) is also reduced due to the receptors down-grading
- The Membrane Theory of Aging: According to this theory it is the age-related changes of the cell’s ability to transfer chemicals, heat and electrical processes that impair it. As we grow older the cell membrane becomes less lipid (less watery and more solid). This impedes its efficiency to conduct normal function and in particular there is a toxic accumulation
- The Decline Theory: The mitochondria are the power producing organelles found in every cell of every organ. Their primary job is to create Adenosine Triphosphate (ATP) and they do so in the various energy cycles that involve nutrients such as Acetyl-L-Carnitine, CoQ10 (Idebenone), NADH and some B vitamins etc. Enhancement and protection of the mitochondria is an essential part of preventing and slowing aging. Enhancement can be achieved with the above mention nutrients, as well as ATP supplements themselves.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 7
Correct
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When looking at the JVP what does the c wave signify:
Your Answer: Isovolumetric ventricular contraction
Explanation:The C wave signifies a rise in the atrial pressure during isovolumetric contraction due to the tricuspid valve bulging into the atria.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 8
Correct
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The cells that secrete HCL are found in which part of the stomach?
Your Answer: Body
Explanation:The stomach can be divided in to different regions. Cardia, fundus, body, antrum and pylorus from proximal end to distal end respectively. Different cell types are distributed accordingly among the regions of the stomach. Cells that secret HCl in the gastric mucosa are known as parietal cells and are abundant in the gastric body region. They have receptors for acetylcholine stimulated via the vagus nerve, histamine receptors and gastrin receptors which stimulate gastric acid secretion. G cells that secret gastrin are abundant in the antrum.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 9
Correct
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The following contributes to the rate of depolarization?
Your Answer: All of the options given
Explanation:Depolarization occurs due to impulses generated by the SA node. As the heart beats to the rhythm of the SA node, certain factors will effect the rate of depolarization. All the mentioned options effect the rate of depolarization.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 10
Incorrect
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Carcinogens found in cigarette smoke can transform proto-oncogenes to oncogenes through:
Your Answer: Inhibiting tumour suppressor genes.
Correct Answer: Point mutations in genomic DNA
Explanation:80% of the pancreatic cancers are environmentally influenced by smoking which increases the risk by 50%. Mutation can occur in the KRAS, p16, SMAD4, and TP53 genes among other tumour suppression genes. Smoking can be implicated in transformation of all these genes. Apart from KRAS all the genes are inactivated in pancreatic cancer. As KRAS is the most commonly altered gene, mutation occurs as point mutation. As smoking is the most common aetiology in pancreatic cancer, and KRAS is the most important gene that is altered. Most commonly cigarette smoke causes point mutation.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 11
Incorrect
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Question 12
Correct
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Which of the following drug can cause galactorrhoea?
Your Answer: Metoclopramide
Explanation:Metoclopramide causes extrapyramidal effects (especially in children and young adults), hyperprolactinaemia, and occasionally tardive dyskinesia on prolonged administration. Also reported are drowsiness, restlessness, diarrhoea, depression, neuroleptic malignant syndrome, rashes, pruritus, oedema.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 13
Correct
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The spinothalamic tracts are particularly concerned with:
Your Answer: Pain and temperature sensations
Explanation:The spinothalamic tracts are part of the anterolateral system in the spinal cord and are responsible for transmitting sensory information related to pain, temperature, and crude touch from the peripheral nervous system to the thalamus in the brain. This sensory information is then relayed to the cerebral cortex for processing. The spinothalamic tracts are divided into two main pathways:
- Lateral spinothalamic tract: Transmits pain and temperature sensations.
- Anterior spinothalamic tract: Transmits crude touch and pressure sensations.
Control of posture: The reticulospinal and vestibulospinal tracts are primarily involved in the control of posture and balance. These tracts originate in the brainstem and help maintain posture by influencing the motor neurons that control axial and proximal muscles.
Voluntary skilled movements: The corticospinal tracts (also known as the pyramidal tracts) are responsible for voluntary skilled movements. These tracts originate in the motor cortex and descend through the brainstem and spinal cord to synapse on motor neurons that control fine motor movements, especially of the distal limbs.
Muscular tone: Muscular tone is primarily regulated by several tracts, including the reticulospinal and vestibulospinal tracts. Additionally, the rubrospinal tract (originating from the red nucleus in the midbrain) also contributes to motor control and muscle tone, particularly of the upper limbs.
Visual input: The optic tracts and pathways (including the optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, and optic radiations) are responsible for transmitting visual information from the retina to the primary visual cortex in the occipital lobe. This pathway processes visual input, including aspects such as color, motion, and depth perception.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 14
Correct
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Which of the following is true regarding platelets?
Your Answer: Normally have a half-life of about 8 days
Explanation:Platelets have no cell nucleus: they are fragments of cytoplasm that are derived from the megakaryocytes of the bone marrow, and then enter the circulation. They have a half life of 5-9 days.
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This question is part of the following fields:
- Haematology
- Medicine
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Question 15
Correct
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The energy needed for glycogen synthesis comes from which compound?
Your Answer: UTP
Explanation:Glycogen synthesis is, unlike its breakdown, endergonic—it requires the input of energy. Energy for glycogen synthesis comes from uridine triphosphate (UTP)
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 16
Incorrect
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In which of the following are the enzymatic mechanisms for producing aldosterone found?
Your Answer: Zona fasciculate
Correct Answer: Zona glomerulosa
Explanation:The zona glomerulosa is the outermost layer of the adrenal gland. In it, aldosterone is secreted as a response to an increase in potassium levels, decreased blood flow, or renin. This secretion is regulated by the renin-angiotensin system.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 17
Incorrect
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A 43 year old female presents with an array of symptoms including weakness, lethargy, dysphagia, dry mouth, gritty sensation in her eyes and increased photosensitivity. In order to confirm the suspected diagnosis, which of the following tests should be performed?
Your Answer: Schirmer’s test
Correct Answer: Labial gland biopsy
Explanation:To confirm the diagnosis, especially in patients with negative anti-Ro or anti-La antibodies, labial gland biopsy is done. In performing a labial biopsy, the surgeon typically makes a shallow 1/2 inch wide incision on either side of the inner lip after numbing the area with a local anaesthetic. Schirmer’s test determines whether the eye produces enough tears to keep it moist. This test can be done for ocular symptoms of Sjogren syndrome but is of no diagnostic importance as it can be positive with many other diseases.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 18
Correct
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If O2 makes up 21% of air, then at one atmosphere (760mmHg) it would be expected that the PO2 of inspired air should be 0,21 x 760 = 160mmHg. In the alveoli the actual measure is 149mmHg because…
Your Answer: Water is equilibrated with air
Explanation:There are several factors that determine the value of alveolar partial oxygen pressure including: the pressure of outside air, the partial pressure of inspired oxygen and carbon dioxide, the rates of total body oxygen consumption and carbon dioxide production, the rates of alveolar ventilation and perfusion. The alveolar partial pressure is lower than the atmospheric oxygen partial pressure. One reason is, as the air enters the lungs, it is humidified by the upper airway and thus the partial pressure of water vapour reduces the oxygen partial pressure as water is equilibrated with air.
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This question is part of the following fields:
- Medicine
- Respiratory
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Question 19
Correct
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Which of the following is the correct way to calculate the anion gap?
Your Answer: (Na + K) – (HCO3 + Cl)
Explanation:The anion gap is the difference between the measured cations (positively charged ions) and the measured anions (negatively charged ions) in serum, plasma, or urine. The magnitude of this difference in the serum is often calculated in medicine when attempting to identify the cause of metabolic acidosis. Anion Gap = ([Na+] + [K+]) − ([Cl−] + [HCO−3])
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This question is part of the following fields:
- Medicine
- Renal
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Question 20
Correct
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The residual cleft of the intermediate lobe of the pituitary is lined by follicles resembling which human gland?
Your Answer: Thyroid
Explanation:The cells located between the two main pituitary lobes form what is known as the intermediate pituitary. This area secretes melanocyte-stimulating hormone and it is only a few cell layers thick. It is rich in follicles filled with colloid, and lined by basophilic cells. This configuration resembles that of another important gland: the thyroid.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 21
Correct
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The primary auditory cortex is:
Your Answer: Brodmann area 41
Explanation:A Brodmann area in the brain is defined by cytoarchitecture, histology and organization of cells:Primary Sensory 3,1,2Primary Motor 4Premotor 6Primary Visual 17Primary Auditory 41Brocas 44
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This question is part of the following fields:
- Medicine
- Neurology
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Question 22
Incorrect
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What percentage of blood is supplied to the liver by the portal vein?
Your Answer: 45%
Correct Answer: 75%
Explanation:The portal vein supplies 75% of the blood to the liver and exceeds the arterial supply of the organ.
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 23
Correct
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Which one of the following antibiotics is safest to use in pregnancy?
Your Answer: Erythromycin
Explanation:Antibiotics that should be avoided in pregnancy are included in the mnemonic: Countless SAFe Moms Take Really Good Care -Clarithromycin, Sulphonamides, Aminoglycosides, Fluoroquinolones, Metronidazole, Tetracyclines, Ribavirin, Griseofulvin, Chloramphenicol
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 24
Incorrect
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The percentage of blood supplied to the liver by the hepatic artery is?
Your Answer: 75%
Correct Answer: 25%
Explanation:The liver receives a dual blood supply from the hepatic portal vein and hepatic arteries. The hepatic portal vein delivers approximately 75% of the liver’s blood supply, and carries venous blood drained from the spleen, gastrointestinal tract, and its associated organs. The hepatic arteries supply arterial blood to the liver, accounting for the remaining quarter of its blood flow. Oxygen is provided from both sources; approximately half of the liver’s oxygen demand is met by the hepatic portal vein, and half is met by the hepatic arteries
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 25
Incorrect
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The process whereby DNA fragments are separated by size and charge is called:
Your Answer: PCR
Correct Answer: Gel electrophoresis
Explanation:Fragments of DNA of varying length can be separated on the basis of their charge and their size by a process called gel electrophoresis. Because DNA contains negatively charged phosphate groups, it will migrate in an electric field toward the positive electrode. Shorter chains migrate more rapidly through the pores of the gel, and thus separation depends on length. DNA bands in the gel can be visualized by various techniques including staining with dyes and autoradiography.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 26
Correct
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Regarding restriction fragment length polymorphisms (RFLP) and Gene Knockout Mouse Models. All are true except:
Your Answer: In knockout mouse models a gene is turned on through targeted mutation
Explanation:In RFLP, polymorphism occurs in 98% of the non coding genome, resulting in no phenotypical change in the organism. A gene is not turned on by a mutation, rather the mutation at the restriction site will alter the DNA and the DNA will now form fragments of different lengths. PCR is a better technique than RFLP.
A knockout, as related to genomics, refers to the use of genetic engineering to inactivate or remove one or more specific genes from an organism. Scientists create knockout organisms to study the impact of removing a gene from an organism, which often allows them to then learn something about that gene’s function.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 27
Incorrect
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Concerning the functional unit of the liver, which segment is most susceptible to hypoxic damage?
Your Answer: Zone 4
Correct Answer: Zone 3
Explanation:From a metabolic perspective, the functional unit is the hepatic acinus (terminal acinus), each of which is centred on the line connecting two portal triads and extends outwards to the two adjacent central veins. The periportal zone I is nearest to the entering vascular supply and receives the most oxygenated blood, making it least sensitive to ischemic injury while making it very susceptible to viral hepatitis. Conversely, the centrilobular zone III has the poorest oxygenation, and will be most affected during a time of ischemia.
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This question is part of the following fields:
- Hepatobiliary
- Medicine
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Question 28
Correct
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The coronary arteries supply which part of the heart’s subendocardial region exclusively in diastole?
Your Answer: Left ventricle
Explanation:It is only during diastole that the blood flows to the subendocardial portion of the left ventricle, as the heart muscle relaxes and the coronary arteries regain their patency.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 29
Correct
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Question 30
Incorrect
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The nucleus tractus solitaries is medullary nucleus that processes the following inputs except:
Your Answer: Taste from the anterior 2/3 of the tongue (CN VII)
Correct Answer: Sensory input from the semi-circular canal (CN VIII)
Explanation:Located in the brain stem is a series of purely sensory nuclei known as tractus solitaries. Inputs of the nucleus tractus solitaries include:Taste information from the facial nerve (anterior 2/3 of the tongue), glossopharyngeal nerve (posterior 1/3) and vagus nerve (small area on the epiglottis).Sensory information from the ear (auricular branch of the vagus nerve).Chemoreceptors and mechanoreceptors of the general visceral afferent pathway (GVA) in the carotid body via glossopharyngeal nerve, aortic bodies, and the sinoatrial node, via the vagus nerve.Chemically and mechanically sensitive neurons of the general visceral afferent pathway (GVA) with endings located in the heart, lungs, airways, gastrointestinal system, pharynx, and liver via the glossopharyngeal and vagus nerves.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 31
Correct
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What effect does osmotic diuresis have on net Na+ excretion?
Your Answer: Markedly increased Na+ excretion
Explanation:Osmotic diuresis is the increase of urination rate caused by the presence of certain substances in the small tubes of the kidneys. The excretion occurs when substances such as glucose enter the kidney tubules and cannot be reabsorbed (due to a pathological state or the normal nature of the substance). The substances cause an increase in the osmotic pressure within the tubule, causing retention of water within the lumen, and thus reduces the reabsorption of water, increasing urine output (i.e. diuresis). Sodium, chloride, potassium are markedly excreted in osmotic diuresis.
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This question is part of the following fields:
- Medicine
- Renal
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Question 32
Correct
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Adrenergic stimulation will lead to myocyte relaxation via the following mechanisms
Your Answer: Increased phosphorylation of phosholamban
Explanation:Phosphorylation of phospholamban, which increases calcium ATPase activity and sequestration of calcium in the sarcoplasmic reticulum. An increased rate of relaxation is explained because cAMP also activates the protein phospholamban, situated on the membrane of the SR, that controls the rate of uptake of calcium into the SR. The latter effect explains enhanced relaxation (lusitropic effect).
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 33
Correct
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A 55-year-old diabetic male presents with a feeling of generally being unwell. He also has a history of atrial fibrillation and epilepsy. His main complaint is a blue tinge to his vision. Which one of his medications is most likely to be responsible?
Your Answer: Sildenafil
Explanation:Blue tinge of vision/cyanopsia is caused due to the intake of sildenafil citrate.Sildenafil citrate (Viagra) is the first oral drug to be widely approved for the treatment of erectile dysfunction. It is a potent and selective inhibitor of type-V phosphodiesterase, the primary form of the enzyme found in human penile erectile tissue, thereby preventing the breakdown of cyclic guanosine monophosphate (cGMP), the intracellular second messenger of nitric oxide.Uses:It is used for the treatment of erectile dysfunction, idiopathic pulmonary hypertension, premature ejaculation, high altitude illness, penile rehabilitation after radical prostatectomy, angina pectoris, and lower urinary tract symptoms.Adverse effects:Mild headache, flushing, dyspepsia, cyanopsia, back pain, and myalgias – due to a high concentration of PDE11 enzyme in skeletal muscle, which shows significant cross-reactivity with the use of tadalafil.It can also cause hypotension, dizziness, and rhinitis.Note: Xanthopsia (yellow-green vision) may occur secondary to treatment with digoxin.
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This question is part of the following fields:
- Medicine
- Pharmacology
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Question 34
Correct
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Which of the following prevents auto-digestion of the stomach by gastric secretions:
Your Answer: Trefoil peptides and mucus- bicarbonate layer.
Explanation:Pepsinogen is the inactive form of pepsin, a protein digesting enzyme. Bombesin is a peptide which stimulates gastrin secreting cells in the stomach increasing production of gastric acid. Ecl or enterochromaffin cells are neuroendocrine cells that aid in the production of gastric acid via the release of histamine. Oxyntic cells are also known as parietal cells and are the main cells secreting gastric hydrochloric acid (HCl). Gastric acid and pepsin are harmful agents for the gastric mucosa and can result in autodigestion. It is therefore protected by several agents including bicarbonate which neutralizes the acidity of gastric acid while Trefoil peptides are a component of gastric mucosa that form a gel like layer in the gastric epithelium protecting it from harmful agents.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 35
Correct
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The collection of genes that are termed the major histocompatibility complex (MHC) are found on:
Your Answer: Short arm of chromosome 6
Explanation:Histocompatibility, or tissue compatibility, is the property of having the same, or sufficiently similar, alleles of a set of genes called human leukocyte antigens (HLA). HLA is the human form of the major histocompatibility complex (MHC) genes found in all vertebrates. On a population level there is a great number of different alleles at each HLA locus on the short arm of chromosome 6
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This question is part of the following fields:
- Immunology
- Medicine
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Question 36
Correct
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Question 37
Correct
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Which are the main hormones secreted by the posterior pituitary gland.
Your Answer: Oxytocin and vasopressin
Explanation:The posterior pituitary gland secretes oxytocin and vasopressin (antidiuretic hormone). These hormones are stored in Herring bodies before being secreted into the bloodstream.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 38
Incorrect
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A lesion that interrupts one optic nerve causes blindness:
Your Answer: In the eye on the contralateral side
Correct Answer: In the eye on the same side as the optic nerve
Explanation:The optic nerve on each side contains medial and lateral fibers originating from the retina. Medial fibers cross at the optic chiasm and become the optic tract ending in the visual cortex of the occipital lobe. If there is a lesion interrupting the “optic nerve” on one side, the same side eye will be completely blind.
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This question is part of the following fields:
- Medicine
- Neurology
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Question 39
Correct
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Question 40
Correct
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The postextrasystolic potentiation of myocardial contractility is due to:
Your Answer: Increase in intracellular Ca2+
Explanation:The postextrasystolic potentiation of myocardial contractility Is not due to ventricular filling. It occurs in isolated locations in the heart and is due to increase availability of intracellular calcium.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 41
Incorrect
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Which of the following options best describes rheumatoid factor?
Your Answer: IgM against the Fc portion of IgA
Correct Answer: IgM against the Fc portion of IgG
Explanation:Rheumatoid factor is an IgM antibody that targets the Fc portion of IgG.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 42
Correct
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A 72 year old female, known with rheumatoid arthritis for last 17 years, presents with recurrent attacks of red eyes with a sensation of grittiness. Which of the following is most likely cause of the red eyes?
Your Answer: keratoconjunctivitis sicca
Explanation:Rheumatoid arthritis is an inflammatory systemic disease associated with some extraarticular manifestations. Keratoconjunctivitis sicca, episcleritis, scleritis, corneal changes, and retinal vasculitis are the most common ocular complications among extraarticular manifestations of RA. The overall prevalence of keratoconjunctivitis sicca also known as dry eye syndrome among patients of RA is 21.2% and is the most common with sense of grittiness in the eyes.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 43
Correct
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A case-control study is being designed to look at the relationship between eczema and a new vaccine for yellow fever. What is the usual outcome measure in a case-control study?
Your Answer: Odds ratio
Explanation:A case–control study (also known as case–referent study) is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute. Case–control studies are often used to identify factors that may contribute to a medical condition by comparing subjects who have that condition/disease (the cases) with patients who do not have the condition/disease but are otherwise similar (the controls).An odds ratio (OR) is a statistic that quantifies the strength of the association between two events, A and B. The odds ratio is defined as the ratio of the odds of A in the presence of B and the odds of A in the absence of B or vice versa.
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This question is part of the following fields:
- Medicine
- Research Skills
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Question 44
Correct
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In the cardiac cycle, all of the following are true except:
Your Answer: Mitral valve is closed by contraction of papillary muscles
Explanation:Mitral valve is closed by contraction of papillary muscles: This statement is incorrect. The mitral valve closes due to the pressure difference between the left ventricle and the left atrium at the onset of ventricular systole. The papillary muscles contract to prevent prolapse of the valve into the atrium but do not cause the valve to close.
The left ventricular volume is maximal at the end of atrial systole: This statement is true. At the end of atrial systole, the atria have pushed the remaining blood into the ventricles, making the ventricular volume maximal (end-diastolic volume).
The left ventricular pressure is maximal just before the aortic valve opens: This statement is true. Left ventricular pressure peaks just before the aortic valve opens, as the ventricle contracts to overcome the pressure in the aorta.
The ejection fraction is about 55%: This statement is true. The ejection fraction, which is the percentage of blood ejected from the ventricles with each contraction, is typically around 55%.
The ‘a’ wave is due to atrial systole: This statement is true. The ‘a’ wave on the venous pressure curve corresponds to atrial systole, reflecting the increased pressure from atrial contraction.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 45
Correct
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The process of DNA amplification and quantification is called:
Your Answer: PCR
Explanation:PCR/polymerase chain reaction is a procedure carried out in a test tube that can be used on the smallest amount of DNA to amplify it, allowing for millions of copies of specific nucleotides to be made.
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This question is part of the following fields:
- Genetics
- Medicine
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Question 46
Incorrect
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Question 47
Correct
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The oligosaccharidases responsible for further digestion of starch after breakdown by the above mentioned enzymes is located where?
Your Answer: Brush border of small intestine
Explanation:The final step in digestion of carbohydrates, which is conversion of disaccharides to absorbable monosaccharides occurs on the small intestinal epithelial cells. The enzymes responsible for this final stage of digestion are not freely found in the intestinal lumen, but they are found as integral membrane proteins in the plasma membrane of the epithelial cell. The apical plasma membrane of the intestinal epithelial cell has numerous microvilli known as the brush border. Thus, the enzymes embedded in those microvilli are referred to as brush border enzymes.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 48
Correct
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Regarding carbohydrates absorption;
Your Answer: Intestinal absorption of sugars is inhibited by the drug phlorizin
Explanation:The main role of insulin is in the uptake of glucose from blood to tissues where it is metabolised. Glycose transporters in the intestines do not depend on the action of insulin. Phlorizin is a competitive inhibitor of SGLT1 and SGLT2 because it competes with glucose for the binding site, reducing intestinal and renal glucose transport.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 49
Correct
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Sympathetic supply to the stomach is derived from
Your Answer: T5-T9 spinal segments via the coeliac ganglion
Explanation:Parasympathetic innervation to the stomach is from the vagus nerve and the sympathetic innervation is from the T5-T9 spinal segments via the coeliac ganglion through the greater splanchnic nerve.
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This question is part of the following fields:
- Gastrointestinal
- Medicine
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Question 50
Incorrect
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With regard to the cell membrane:
Your Answer:
Correct Answer: It consists of an outer hydrophilic & an inner hydrophobic layer
Explanation:The cell membrane consists primarily of a thin layer of amphipathic phospholipids that spontaneously arrange with the hydrophobic tail regions on the inside and the hydrophilic head regions outside. Membranes typically have a large content of proteins, around 50% of membrane volume.
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This question is part of the following fields:
- Cell Biology
- Medicine
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