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Question 1
Incorrect
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Regarding the innervation of cerebral blood vessels, which of the following triggers a vasoconstrictor effect?
Your Answer: Substance P
Correct Answer: Neuropeptide-Y
Explanation:Substance P is a potent vasodilator, VIP or vasoactive intestinal peptide has vasodilator properties in the intestines. PHM 27 is a potent calcitonin receptor agonist; endogenous analogue of human VIP. CGRP or Calcitonin Gene-Related Peptide is a vasodilator which is found to play an important role in migraines. Neuropeptide Y is a strong vasoconstrictor.
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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 33 year old female presents with dyspnoea, myalgia, arthralgia and a skin rash. The presence of which of the following antibodies would be the most specific for SLE?
Your Answer: Anti-Sm
Explanation:Anti-Sm antibodies are essential for diagnosis of SLE, especially in anti-dsDNA-negative patients. ANA are also found in 95% of the patients with SLE but they may also occur with other conditions like Juvenile inflammatory arthritis, chronic activity hepatitis, and Sjogren’s syndrome. Anti-Ro, although also found with SLE are more characteristic of Sjogren Syndrome. RF is usually associated with rheumatoid arthritis and cANCA with Wegener’s granulomatosis, Churg Strauss, and microscopic polyangiitis.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 3
Correct
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Depolarization spreads rapidly through cardiac muscle fibers because of the presence of:
Your Answer: Gap junctions
Explanation:The cardiac muscles have gap junctions in between the cells. They allow for the formation of low resistance passages, which allow ions to diffuse through every muscle fiber rapidly and result in the cardiac muscles functioning as a syncytium, without any protoplasmic bridges involved.
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This question is part of the following fields:
- Cardiovascular
- Medicine
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Question 4
Incorrect
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In the urea cycle, which substance is formed in the mitochondria?
Your Answer: Ornithine
Correct Answer: Carbamoyl phosphate
Explanation:Before the urea cycle begins ammonia is converted to carbamoyl phosphate in the mitochondria.
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This question is part of the following fields:
- Medicine
- Metabolism
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Question 5
Incorrect
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A 28 year old man was rushed to the hospital after experiencing sudden onset chest pain while playing football. He has never felt such pain in the past. However, one of his uncles had a similar sudden discomfort at a young age and he passed away following a heart problem. The following vitals are recorded on examination:BP: 101/74 mmHgRR: 22 breaths/minPR: 87 beats/min Physical examination reveals abnormally long fingers and on asking the man to hold the opposite wrist, the thumb and little finger overlap each other. He is not taking any medication regularly and past medical/surgical history is not significant. He admits to smoking half pack of cigarettes/day for the last 10 years but denies abusing any illicit drugs. Which of the following explanation most likely explains the disease process in this man?
Your Answer: Impaired hydroxylation of lysine and proline amino acids on collagen
Correct Answer: A defect of the glycoprotein structure which usually wraps around elastin
Explanation:Aortic dissection is defined as separation of the layers within the aortic wall. Tears in the intimal layer result in the propagation of dissection (proximally or distally) secondary to blood entering the intima-media space. This can be caused as a result of both congenital or acquired factors like chronic uncontrolled hypertension. This patient shows no sign of hypertension but his physical examination hints towards Marfan Syndrome. Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder affecting the microfibrils and elastin in connective tissue throughout the body. MFS is associated with pathological manifestations in the cardiovascular system (e.g., mitral valve prolapse, aortic aneurysm, and dissection), the musculoskeletal system (e.g., tall stature with disproportionately long extremities, joint hypermobility), and the eyes (e.g., subluxation of the lens of the eye). Decreased collagen production occurs in ageing, hydroxylation defects are present in vitamin C deficiency, copper deficiency affecting lysyl oxidase enzyme occurs in Menke’s disease.
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This question is part of the following fields:
- Connective Tissue
- Medicine
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Question 6
Incorrect
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In which phase do chromosomes in the nucleus become condensed into well-defined chromosomes?
Your Answer: Prophase
Correct Answer: Metaphase
Explanation:Prophase begins when the nucleus envelope disintegrates and the chromosomes start to condense. The chromosomes consist of two sister chromatids that are joined at a constriction known as centromere. When the cell reaches the metaphase the chromosomes are completely condensed and ready to align on the equatorial plate
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This question is part of the following fields:
- Genetics
- Medicine
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Question 7
Incorrect
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Which cell type functions as the critical bridge between innate and adaptive immune systems, by activating naïve T lymphocytes?
Your Answer: Natural killer cells
Correct Answer: Dendritic cells
Explanation:Dendritic cells are antigen presenting cells. They express class II MHC and T cell co-stimulatory molecules. They bind antigens and present them to native T cells and in the process activate the specific T cell against that antigen.
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This question is part of the following fields:
- Immunology
- Medicine
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Question 8
Correct
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Emulsification of dietary lipids is brought about by
Your Answer: Bile salts
Explanation:Digestion of fats can begin in the mouth where lingual lipase breaks down some short chain lipids into diglycerides. However fats are mainly digested in the small intestine. The presence of fat in the small intestine produces hormones that stimulate the release of pancreatic lipase from the pancreas and bile from the liver which helps in the emulsification of fats for absorption of fatty acids.
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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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What is the most important source of heat production in the body?
Your Answer: Skeletal muscle contraction
Explanation:Thermogenesis is the process by which organisms produce heat. Through skeletal muscle contraction, or shivering, ATP is converted into kinetic energy, some of which converts into heat. These muscle contractions produce about 70% of total body heat.
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This question is part of the following fields:
- Endocrinology
- Medicine
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Question 10
Correct
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The process by which DNA fragments are separated by gel and transferred onto a membrane sheet is called:
Your Answer: Southern blotting
Explanation:A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization. The other forms of blotting involve the use of RNA and proteins.
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This question is part of the following fields:
- Genetics
- Medicine
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