Medical Biochemistry II — MBMB 2200 Paper A OmpathStudy

Continued from $1. MEDICAL BIOCHEMISTRY II - ANSWER KEY MBMB2200 - Paper A --- SECTION A: MULTIPLE CHOICE QUESTIONS [35 MARKS] Question 1 Smooth muscles are confined to the following tissues, except: A. Uterus B. Arteries C. Heart D. Veins E. GIT system Answer: C. Heart Explanation: The heart contains cardiac muscle, which is striated and involuntary, not smooth muscle. Smooth muscle is found in the uterus, blood vessels (arteries and veins), and the gastrointestinal tract. --- Question 2 The following are components of the reticulo-endothelial system, except: A. The spleen B. The pancreas C. The liver D. The bone marrow E. The blood Answer: B. The pancreas Explanation: The reticuloendothelial system includes organs involved in immune function and phagocytosis: spleen, liver, bone marrow, and circulating blood cells. The pancreas is primarily an endocrine and exocrine gland, not part of the reticuloendothelial system. --- Question 3 The following statements are true regarding cerebral metabolism, except: A. Brain receives a constant supply of glucose through the blood stream and cannot store glycogen B. Ketone and glucose can both be fuel molecules for the brain C. Ketone bodies and lactate are important substrates for energy and synthesis of lipids and amino acids D. The brain cells adapt quickly and utilize ketone bodies in the event of starvation E. Normally, glucose is the sole preferred fuel of the brain Answer: D. The brain cells adapt quickly and utilize ketone bodies in the event of starvation Explanation: Brain adaptation to ketone bodies takes several days to weeks, not quickly. The brain normally uses glucose but can adapt to use ketones during prolonged starvation or metabolic states like ketosis. --- Question 4 Erythrocyte Production: A. Is inhibited by anemia due to blood loss B. Production is impaired at high altitude C. Production is stimulated by erythropoietin D. Are produced by the bone marrow of almost every bone in the body during the first 5 years of life E. Are not produced in the fetal liver Answer: C. Production is stimulated by erythropoietin Explanation: Erythropoietin, produced by the kidneys, stimulates red blood cell production in response to hypoxia. Blood loss actually stimulates (not inhibits) erythropoiesis, and high altitude also stimulates production due to lower oxygen levels. --- Question 5 Bile salts: A. Are converted to secondary bile salts in the liver B. Inhibit fat digestion C. Inhibit intestinal motility D. Help digestion of proteins E. Stimulate bile secretion from the liver Answer: E. Stimulate bile secretion from the liver Explanation: Bile salts facilitate fat digestion and absorption. Secondary bile salts are formed in the intestine by bacterial action, not in the liver. They enhance, not inhibit, fat digestion. --- Question 6 Individuals at risk of developing fatal Rh incompatibility are: A. Any Rh+ fetus B. Second Rh- fetus of Rh+ mother C. Second Rh+ fetus of Rh- mother D. Rh- mother E. Rh- father Answer: C. Second Rh+ fetus of Rh- mother Explanation: Rh incompatibility occurs when an Rh- mother carries an Rh+ fetus. The second pregnancy is at risk because the mother was sensitized during the first pregnancy and developed antibodies against Rh+ blood. --- Question 7 The following are functions of the liver, except: A. Secretion of bile B. Storage of glycogen C. Synthesis of clotting factors D. Synthesis of immunoglobulins E. Detoxification of xenobiotics Answer: D. Synthesis of immunoglobulins Explanation: Immunoglobulins (antibodies) are synthesized by plasma cells, not the liver. The liver performs all other listed functions: bile secretion, glycogen storage, clotting factor synthesis, and detoxification. --- Question 8 In the vitreous humor glucose is converted to sorbitol by the enzyme: A. Sorbitol dehydrogenase B. Aldolase reductase C. Aldose reductase D. Aldose dehydrogenase E. None of the above Answer: C. Aldose reductase Explanation: Aldose reductase converts glucose to sorbitol in the polyol pathway. This is particularly important in diabetic complications where excess glucose leads to sorbitol accumulation in tissues like the eye. --- Question 9 Substances which are inactivated and excreted by the liver include the following except: A. Amino acids B. Drugs C. Steroid hormones D. Enzymes E. Bilirubin Answer: A. Amino acids Explanation: Amino acids are not typically "inactivated" by the liver; they are metabolized for energy or used in protein synthesis. The liver does inactivate and excrete drugs, steroid hormones, enzymes, and bilirubin. --- Question 10 One of the following statements is true regarding bile: A. Bile is synthesized in the gall bladder B. Bile salts are hydrophobic molecules C. Most bile salts are absorbed in the terminal ileum D. Bile salts are the breakdown products of hemoglobin E. The secretion of bile is controlled by cholecystokinin Answer: C. Most bile salts are absorbed in the terminal ileum Explanation: About 95% of bile s