3.Biochemistry Prep Pyq.PDF

NAD and NADP coenzymes are also involved in a variety of oxidation-reduction reactions as a part of oxidoreductases enzymes e.g. Incorrect options Option A: Riboflavin The coenzyme forms of riboflavin are FAD and FMN They are also involved in oxidation-reduction reactions, e.g., succinate dehydrogenase, fatty acyl CoA dehydrogenase Option B: Thiamine Thiamine pyrophosphate (TPP) is the active coenzyme form of thiamine It is used by enzymes pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase for oxidative decarboxylation. Option D: Biotin Biotin is an essential cofactor for all carboxylase enzymes such as pyruvate carboxylase, acetyl-CoA carboxylase, propionyl-CoA carboxylase, and 3-methylcrotonyl-CoA-carboxylase Page 19 125 Previous Year Questions 1. Which glycosaminoglycan (GAG) is present in synovial fluid? A. Heparin B. Keratan sulfate C. Chondroitin sulfate D. Hyaluronic acid ---------------------------------------- 2. Which of the following GAG has anticoagulant activity A. Heparin B. Keratan sulfate C. Chondroitin sulfate D. Hyaluronic acid ---------------------------------------- 3. A patient came to the hospital with a complaint of abdominal pain. Routine investigations were unremarkable. On observation, the urine turned black on standing. Which of the following enzymes is likely to be defective in this patient? A. Homogentisate oxidase B. Xanthine oxidase C. Phenylalanine hydroxylase D. Dihydric orotate dehydrogenase ---------------------------------------- 4. Which absorbs least water? A. Mucilage B. Cellulose C. Gums D. Pectin ---------------------------------------- 5. Enzyme deficient in Gaucher disease : A. Betagalacto cerebrosidase B. Betaglucocerebrosidase C. Glucose-6-phosphate D. Alpha glucocerebrosidase ---------------------------------------- 6. In a patient who has experienced prolonged starvation, which of the following tests would yield positive results when conducted on their urine? 126 A. Benedict's test B. Rothera's test C. Biuret test D. Emulsion test ---------------------------------------- 7. The meal that exhibits the highest thermic effect is characterized by A. Protein B. Fat C. Carbohydrates D. Mixed meal having all 3 in equal amount ---------------------------------------- 8. How many calories are provided by a TPN bag containing 100g of glucose, 30g of amino acids, and 40g of lipids? A. 840 KCal B. 880 KCal C. 640 Kcal D. 680 Kcal ---------------------------------------- 9. Glucose is stored in the form of glycogen because A. It is compact B. It has multiple reducing ends C. It can be stored at multiple organs D. It can provide glucose for about 1 week when needed ---------------------------------------- 10. The given chemical structure is of Page 2 127 A. Keratan sulfate B. Chondroitin sulfate C. Heparin D. Dermatan sulfate ---------------------------------------- 11. Low glycemic index food is? A. Easily digestible B. Increases plasma glucose C. Has slower absorption D. Increase glycogen deposits ---------------------------------------- 12. The graph shown below is the titration curve of a biochemical compound. Which of the following statement is true? A. The maximum buffering capacity of the compound is represented by points A and B B. The points A and B represent the range of maximum ionization of the amine and carboxyl group C. The compound has three ionizable side chains D. The compound has one ionizable group ---------------------------------------- 13. Which of the following statements is false regarding proteoglycans? Page 3 128 A. Carries negative charge B. Chondroitin sulfate is a glycosaminoglycans C. Made of amino acids and sugars D. Holds less water ---------------------------------------- 14. Which of the options listed below possesses both protective and lubricating qualities? A. Collagen B. Mucin C. Albumin D. Immunoglobulin ---------------------------------------- 15. Which of the following enzymes is irreversible step in gluconeogenesis? A. Pyruvate carboxylase B. Phosphoenolpyruvate carboxylase C. Pyruvate kinase D. Glucose-6-phosphatase ---------------------------------------- 16. What is the likely diagnosis for a 36-year-old man who has been experiencing bluish-black discoloration of the sclera and pinna for the past 6 months, along with a history of black urine upon standing since childhood? A. Phenylketonuria B. Alkaptonuria C. Tyrosinemia D. Maple syrup urine disease ---------------------------------------- Correct Answers Question Correct Answer Question 1 4 Question 2 1 Question 3 1 Question 4 2 Question 5 2 Question 6 2 Question 7 1 Question 8 2 Page 4 129 Question 9 1 Question 10 2 Question 11 3 Question 12 1 Question 13 4 Question 14 2 Question 15 3 Question 16 2 Solution for Question 1: Correct option: Option: d Hyaluronic acid is a type of glycosaminoglycan (GAG) that is found in high concentrations in synovial fl uid, which is the fluid that lubricates and cushions the joints. It is a major component of the synovial fluid and plays a crucial role in maintaining the viscoelastic properties of the fluid, allowing for smooth joint movement. Incorrect options: Option a. Heparin: Heparin is a GAG primarily found in mast cells and is an important anticoagulant in t he bloodstream. It is not typically found in significant amounts in synovial fluid. Heparin functions by inh ibiting blood clotting factors and preventing the formation of blood clots. Option b. Keratan sulfate: Keratan sulfate is a GAG that is commonly found in various connective tissu es, including cartilage, cornea, and bone. It contributes to the structural integrity of these tissues. While it may be present in trace amounts in synovial fluid, it is not the main GAG found in this fluid. Option c. Chondroitin sulfate: Chondroitin sulfate is another GAG that is widely distributed in connectiv e tissues, including cartilage, bone, and skin. It provides structural support and helps maintain tissue h ydration. Although chondroitin sulfate may be present in small quantities in synovial fluid, it is not the pr imary GAG found in significant concentrations in this fluid. Solution for Question 2: Correct Option: Option A. Heparin is a glycosaminoglycan (GAG) that possesses anticoagulant activity. It acts as a natural antico agulant by inhibiting the activity of various clotting factors in the blood, particularly thrombin and factor Xa. Heparin is primarily synthesized and stored in mast cells, and it is released into the bloodstream w hen needed to prevent the formation of blood clots. Incorrect Options: Option B. Keratan sulfate: Keratan sulfate is a GAG that is mainly found in connective tissues such as cartilage and cornea. It does not possess anticoagulant properties. Page 5 130 Option C. Chondroitin sulfate: Chondroitin sulfate is another GAG that is abundant in various connectiv e tissues, including cartilage and tendons. It does not have anticoagulant activity. Option D. Hyaluronic acid: Hyaluronic acid is a GAG that is widely distributed throughout the body, incl uding in synovial fluid, skin, and connective tissues. It does not have anticoagulant properties. Solution for Question 3: Correct Option: A The patient's black urine suggests the presence of a condition called alkaptonuria. Alkaptonuria is a rare inherited disorder caused by a deficiency of the enzyme homogentisate oxidase. This enzyme is responsible for the breakdown of homogentisic acid, a product of the metabolism of the amino acids phenylalanine and tyrosine. When homogentisate oxidase is deficient, homogentisic acid accumulates in the body and is excreted in the urine, leading to the characteristic dark or black urine on standing. Incorrect options: Option B. Xanthine oxidase: Xanthine oxidase deficiency is associated with a condition called xanthinur ia, which results in the accumulation of xanthine and hypoxanthine. It does not cause black urine or ab dominal pain, so it is not the likely enzyme defect in this case. Option C. Phenylalanine hydroxylase: Phenylalanine hydroxylase deficiency is seen in a condition calle d phenylketonuria (PKU). PKU is characterized by the inability to metabolize phenylalanine properly, le ading to its accumulation in the body. PKU does not cause black urine, so it is not the likely enzyme de fect in this case. Option D. Dihydric orotate dehydrogenase: There is no known enzyme called dihydric orotate dehydro genase. Therefore, this option is incorrect. Solution for Question 4: Correct Option B: Cellulose is a polysaccharide found in the cell walls of plants. It is a complex carbohydrate that forms a rigid structure and is not soluble in water. Due to its structure and composition, cellulose has the ability to absorb the least amount of water compared to the other options. Incorrect options: Option A. Mucilage: Mucilage refers to a sticky substance produced by plants. It has the ability to absorb and hold water, acting as a gel-like sub stance. Mucilage has high water-holding capacity and can absorb significant amounts of water. Option C. Gums: Gums, such as gum arabic or guar gum, are complex carbohydrates derived from pla nts. They have the ability to absorb water and form a gel-like consistency. Gums are commonly used a s thickening agents and can absorb significant amounts of water. Option D. Pectin: Pectin is a polysaccharide found in the cell walls of fruits and vegetables. It is known for its ability to form gels and is commonly used as a thickening agent in food processing. Pectin has the capacity to absorb and hold water. Page 6 131 Solution for Question 5: Correct option B "Betaglucocerebrosidase" (correct option): This term appears to be a variation of the correct enzyme name, which is "beta-glucocerebrosidase." In Gaucher disease, there is a deficiency or malfunction of this enzyme, leading to the accumulation of glucocerebroside within cells, particularly macrophages. This accumulation can cause damage to various tissues and organs in the body. Incorrect options: Option A. "Betagalacto cerebrosidase": This is not the correct enzyme deficient in Gaucher disease. It seems to be a combination of the terms "beta-galactosidase" and "cerebrosidase." Beta-galactosidase is deficient in another genetic disorder known as GM1 gangliosidosis, while cerebrosidase is not specifi cally associated with any known diseases. Option C. "Glucose-6-phosphate": This is not the enzyme deficient in Gaucher disease. Glucose-6-pho sphate is a molecule involved in various metabolic pathways, including glucose metabolism and the pe ntose phosphate pathway. It is not directly related to Gaucher disease. Option D. "Alpha glucocerebrosidase": This is an incorrect term. The correct enzyme deficient in Gauc her disease is "beta-glucocerebrosidase." The term "alpha glucocerebrosidase" does not refer to any k nown enzyme or condition. Solution for Question 6: Option B. Rothera's test: Rothera's test is done for the detection of ketone bodies which are produced as a result of starvation/fasting. The purple color ring at the junction of 2 liquids is a positive test. Given positive by acetoacetate and acetone Incorrect Choices: Option A. Benedict test: Used for the detection of reducing sugars in a complex Simple carbohydrates containing a free ketone or aldehyde functional group can be identified with this test. The test is based on Benedict’s reagent (also known as Benedict’s solution) When exposed to reducing sugars, the reactions undergone by Benedict’s reagent result in the formation of a brick-red precipitate, which indicates a positive Benedict test. Option C. Biuret test: The Biuret test is used to detect the presence of proteins. The test is done for copper ions in an alkaline solution can form a complex with the peptide bonds in proteins, resulting in a change in color, from blue to violet. Page 7 132 Option D. Emulsion test: The emulsion test is a method to determine the presence of lipids using wet chemistry. Solution for Question 7: The thermic effect of food (TEF) refers to the increase in energy expenditure that occurs after consumi ng a meal. It is the energy required for the digestion, absorption, and metabolism of nutrients. The TEF varies depending on the macronutrient composition of the meal. Correct Option A: Protein: Protein has the highest thermic effect among the three macronutrients. Approximately 20-30% of the energy from protein is used during the digestion and metabolism process. This means that cons uming a meal rich in protein can significantly increase energy expenditure compared to meals with othe r macronutrients. Incorrect Options: Option B: Fat: This option is incorrect. Fat has a lower thermic effect compared to protein. Only about 0 -5% of the energy from fat is used during digestion and metabolism. This means that consuming a high-fat meal results in a lower increase in energy expenditure compared to a high-protein meal. Option C: Carbohydrates: This option is incorrect. Carbohydrates have a moderate thermic effect. Appr oximately 5-10% of the energy from carbohydrates is used during digestion and metabolism. While car bohydrates do increase energy expenditure, they have a lower thermic effect compared to protein. Option D: Mixed meal having all three in equal amount: This option is incorrect. While a mixed meal co ntaining protein, fat, and carbohydrates will require energy for digestion and metabolism of all three ma cronutrients, the thermic effect will still be higher for protein compared to the other macronutrients. Solution for Question 8: Correct Option B: To calculate the number of calories delivered in the TPN (Total Parenteral Nutrition) bag, we need to k now the caloric value of each macronutrient. The caloric values per gram for each macronutrient are as follows: Glucose: 4 calories per gram Amino acids: 4 calories per gram Lipids (fats): 9 calories per gram Now let's calculate the calories for each component of the TPN bag: Now, let's add up the calories from each component: 400 calories (glucose) + 120 calories (amino acids) + 360 calories (lipids) = 880 calories Therefore, the correct option is b) 880 Kcal, as it represents the total amount of calories delivered in th e TPN bag. Incorrect options: Page 8 133 Option A. 840 KCal: This option doesn't take into account the calories from lipids, resulting in an incorr ect lower value. Option C. 640 Kcal: This option only considers the calories from glucose and amino acids, excluding th e calories from lipids. Option D. 680 Kcal: This option only considers the calories from glucose and amino acids, excluding th e calories from lipids. Solution for Question 9: Correct Option A: Glucose is stored in the form of glycogen because it is a compact and highly branched molecule. Glycogen is a polysaccharide composed of many glucose mol ecules linked together through alpha-1,4-glycosidic bonds and branched with alpha-1,6-glycosidic bond s. By storing glucose as glycogen, the body can efficiently pack a large amount of glucose molecules into a compact and readily available form. This compact storage all ows for efficient storage of glucose within cells, especially in tissues such as the liver and muscles, wh ere glycogen serves as a reserve energy source. When the body needs energy, glycogen can be quickly broken down into individual glucose molecules through a process called glycogenolysis. This enables the release of glucose into the bloodstream to pr ovide energy for various tissues and organs. Incorrect Options: Option B. It has multiple reducing ends: While it is true that glycogen has multiple reducing ends due to its branched structure, this is not the primary reason why glucose is stored as glycogen. The compact nature of glycogen is the main reason for its storage. Option C. It can be stored at multiple organs: Although glycogen can be stored in multiple organs, such as the liver and muscles, this is not the main reason why glucose is stored as glycogen. The compact nature of glycogen is the primary reason for its storage. Option D. It can provide glucose for about 1 week when needed: The storage capacity of glycogen vari es depending on the individual and their glycogen reserves. However, the storage duration of glycogen is not precisely limited to one week. It can vary based on factors such as activity level, diet, and individ ual metabolic rate. Solution for Question 10: Correct Option B: Chondroitin sulfate is a glycosaminoglycan (GAG) that is a major component of the extracellular matrix and connective tissues in the body. It consists of repeating units of N-acetylgalactosamine (GalNAc) an d glucuronic acid (GlcA) or iduronic acid (IdoA). Chondroitin sulfate provides structural support and ela sticity to various tissues, including cartilage, tendons, ligaments, and skin. Incorrect Options: Page 9 134 Options A. Keratan sulfate: Keratan sulfate is another type of glycosaminoglycan. It consists of repeati ng units of galactose and N-acetylglucosamine. It is commonly found in the cornea of the eye and cartil age, and it helps maintain the structural integrity of these tissues. Options C. Heparin: Heparin is a different type of glycosaminoglycan that is highly sulfated. It consists of repeating units of glucuronic acid and N-acetylglucosamine. Heparin is an anticoagulant and is prim arily produced and stored in mast cells. It plays a role in preventing blood clotting. Options D. Dermatan sulfate: Dermatan sulfate is another glycosaminoglycan that is composed of repe ating units of iduronic acid and N-acetylgalactosamine. It is found in various tissues, including skin, blo od vessels, and heart valves. Dermatan sulfate provides structural support and flexibility to these tissue s. Solution for Question 11: Correct option C Has slower absorption: This option is correct. Low glycemic index foods are characterized by carbohydrates that are digested and absorbed more slowly by the body. This slow absorption leads to a slower and more controlled release of glucose into the bloodstream, resulting in a more stable and sustained blood glucose response. Incorrect options: Option A. Easily digestible: This option is incorrect. The digestibility of food is not directly related to its glycemic index. The glycemic index measures how quickly carbohydrates in food are broken down and absorbed, which is not solely determined by digestibility. Option B. Increases plasma glucose: This option is incorrect. Foods with a high glycemic index tend to cause a rapid increase in blood glucose levels, while low glycemic index foods result in a slower and more gradual increase in blood glucose levels. Option D. Increase glycogen deposits: This option is incorrect. Glycogen deposits refer to the storage f orm of glucose in the body, primarily found in the liver and muscles. The glycemic index of a food does not directly influence glycogen deposits. Instead, it reflects how quickly carbohydrates from the food ar e converted into glucose and affect blood glucose levels. Solution for Question 12: Correct Option: Option a. The statement "The maximum buffering capacity of the compound is represented by points A and B" is true. Points A and B on the titration curve correspond to the region where the compound acts as a buffer. In this region, the compound can effectively resist changes in pH by accepting or donating protons. Incorrect Option: Option b. The statement "The points A and B represent the range of maximum ionization of the amine and carboxyl group" is incorrect. Points A Page 10 135 and B do not represent the maximum ionization of the amine and carboxyl groups specifically. They re present the region of maximum buffering capacity, but the overall ionization of the amine and carboxyl groups can occur over a broader pH range. Option c. The statement "The compound has three ionizable side chains" is incorrect. Glycine, being a simple amino acid, does not have any ionizable side chains. It has a carboxyl group (COOH) and an amine group (NH2), both of which can undergo ionization. Optiond. The statement "The compound has one ionizable group" is incorrect. Glycine has two ionizabl e groups: the carboxyl group (COOH) and the amine group (NH2). These groups can gain or lose proto ns (H+) depending on the pH of the solution. Solution for Question 13: Correct Option: Option d. Holds less water: This is the correct option. Proteoglycans have a high capacity to hold water due to the presence of the highly hydrophilic glycosaminoglycan (GAG) chains. The negatively charge d GAGs attract water molecules, allowing proteoglycans to maintain hydration within tissues. Therefore , the statement that proteoglycans hold less water is not true. Incorrect option: Option a. Carries negative charge: This is a true statement about proteoglycans. Proteoglycans are heavily glycosylated molecules composed of a core protein and long chains of repeating disaccharides called glycosaminoglycans (GAGs). The GAG chains are negatively charged due to the presence of sulfate and carboxylate groups, giving proteoglyc ans an overall negative charge. Option Chondroitin sulfate is a good glycosaminoglycan (GAG) that is commonly found as a component of proteoglycans. Chondroitin sulfate chains can attach to a core protein to form a proteoglycan structure. Optionc. Made of amino acids and sugars: This is a true statement about proteoglycans. Proteoglycans consist of a core protein that is composed of amino acids and long chains of sugars called glycosaminoglycans (GAGs). The GAGs are made up of repeat ing disaccharide units, which include a sugar and an amino sugar. Solution for Question 14: Correct Ans. B Mucin is a glycoprotein that is a major component of mucus. Mucus is a slimy and viscous substance that lines various surfaces in the body, such as the respiratory tract, gastrointestinal tract, and reproductive tract. Mucin plays a crucial role in protecting these surfaces by trapping pathogens, dust, and other foreign particles, preventing them from entering the body. Additionally, mucin acts as a lubricant, reducing friction and facilitating the movement of materials across the epithelial surfaces. Therefore, option B is the correct answer. Incorrect option: Page 11 136 Option A: Collagen Collagen is a fibrous protein found in connective tissues such as skin, tendons, and bones. It provides structural support and strength to tissues and is not primarily known for its protectiv e or lubricating properties. Therefore, option A is incorrect. Option C: Albumin Albumin is a protein found in blood plasma and is involved in maintaining osmotic pr essure and transporting various substances. While albumin has important physiological functions, it do es not have a prominent role in providing protection or lubrication. Therefore, option C is incorrect. Option D: Immunoglobulin Immunoglobulins, also known as antibodies, are proteins produced by the i mmune system in response to foreign substances (antigens). They play a crucial role in the immune re sponse, recognizing and binding to specific antigens to neutralize or eliminate them. Immunoglobulins primarily function in immunity rather than providing protection or lubrication. Therefore, option D is incorrect. Solution for Question 15: Correct Answer: C: Pyruvate kinase: Pyruvate kinase is not directly involved in gluconeogenesis. It catalyzes the conversion of phosphoenolpyruvate (PEP) to pyruvate in the final step of glycolysis, which is the breakdown of glucose to produce energy. Incorrect Option Option A. Pyruvate carboxylase: Pyruvate carboxylase is an enzyme that plays a key role in gluconeogenesis. It catalyzes the conversion of pyruvate to oxaloacetate, which is an important intermediate in the gluconeogenesis pathway. Option B. Phosphoenolpyruvate carboxylase: Phosphoenolpyruvate carboxylase is also involved in gluconeogenesis. It catalyzes the conversion of oxaloacetate to phosphoenolpyruvate (PEP), another crucial intermediate in the gluconeogenesis pathway. Option D. Glucose-6-phosphatase: Glucose-6-phosphatase is an enzyme that is essential for gluconeogenesis. It catalyzes the hydrolysis of glucose-6-phosphate to produce glucose, which can be released into the bloodstream. Solution for Question 16: Correct Option B: Alkaptonuria Alkaptonuria is an uncommon hereditary condition. It occurs when the body cannot make enough homogentisic dioxygenase (HGD). This enzyme is utilized to degrade the hazardous chemical homogentisic acid. When the body does not make enough HGD, homogentisic acid accumulates. The accumulation of homogentisic acid causes discoloration and brittleness of bones and cartilage. This usually results in osteoarthritis, particularly in your spine and big joints. When exposed to air, in those with alkaptonuria urine turns dark brown or black. Page 12 137 Incorrect Options: Option A: PKU is defined by the absence or deficiency of an enzyme called phenylalanine hydroxylase (PAH), which is responsible for the amino acid phenylalanine's processing. As a result of too much phenylalanine in the body, untreated individuals may have a musty or mouse-like odor in their breath, skin, or urine. Such a condition is not mentioned here. Therefore, the diagnosis cannot be PKU. Option C: Patients with tyrosinemia are unable to completely break down (metabolize) the amino acid t yrosine. By-products of this amino acid build up, causing a variety of symptoms. These by-products als o cause body fluids like urine and sweat to smell like boiled cabbage. Such a condition is not mentioned here. Therefore, the diagnosis cannot be Tyrosinemia. Option D: Patients with MSUD are unable to break down amino acids called leucine, isoleucine, and va line. Very high levels of these amino acids are harmful. One of the characteristic symptoms of MSUD is sweet-smelling urine, which gives the condition its name. The patient in this case does not present suc h a condition. Hence, the case does not suggest MSUD. Page 13 138 Previous Year Questions 1. In a patient who hails from a Mediterranean country and travels to Africa, they contract malaria. After receiving treatment with primaquine, the patient subsequently develops hemolytic anemia. Which pathway deficiency in the enzyme could potentially be responsible for this condition? A. Glycolysis B. Gluconeogenesis C. Hexose monophosphate (HMP) pathway D. Luebering-Rapoport pathway ---------------------------------------- 2. Which enzyme deficiencies could potentially be the cause of exercise intolerance and cramps in an adolescent male patient? A. Myophosphorylase B. Hexokinase C. Glucose-6-phosphatase D. Hepatic glycogen phosphorylase ---------------------------------------- 3. What is the enzyme defect if a child with anemia, thrombocytopenia, bony pain, and hepatosplenomegaly shows a "crumpled tissue paper" appearance on light microscopy of bone marrow aspirate? A. Glucocerebrosidase B. Sphingomyelinase C. Hexosaminidase D. Glucose6-phosphatase ---------------------------------------- 4. In a fasting state, glucagon promotes the production of glucose by which of the following pathways? A. Glycolysis and gluconeogenesis B. Gluconeogenesis and glycogenolysis C. Glycogenesis and gluconeogenesis D. Only gluconeogenesis ---------------------------------------- 5. In Von Gierke's disease, which enzyme is commonly observed to be deficient? A. Glucose-6-phosphatase B. Branching enzyme C. Debranching enzyme D. Muscle glycogen phosphorylase ---------------------------------------- 139 6. Which of the subsequent cellular pathways is found solely within the cytoplasm of a cell? A. Beta oxidation B. TCA cycle C. Glycolysis D. Urea cycle ---------------------------------------- 7. A 4-year-old child presents with easy fatigability. The mother also complains that the child has increased hunger between meals, which is relieved after food. Liver biopsy revealed no glycogen. The most likely deficient enzymeis? A. Branching enzyme B. Glycogen synthase C. Debranching enzyme D. Glucose-6-phosphatase ---------------------------------------- 8. In the OPD, a patient with liver damage presented, and the image shows their eyes being examined. Which of the following factors is responsible for causing this condition? A. Copper B. Glucose C. Galactose D. Mannose ---------------------------------------- 9. A patient who was in excruciating pain all over his body was taken to the hospital. In recent years, he has experienced these incidents frequently. When exercising vigorously, the ache begins. Anemia was detected on blood examination along with elongated RBC as opposed to concave ones. It was determined that he had sickle cell anemia. What substitution takes place in sickle cell anemia? A. Substitution of valine by glutamic acid at the 6th position B. Substitution of glutamic acid by valine at the 6th position C. Substitution of valine by glutamic acid at the 5th position D. Substitution of glutamic acid by valine at the 5th position Page 2 140 ---------------------------------------- 10. Glycogen phosphorylase is activated by: A. Calcium B. Glucose-6-phosphate C. Insulin D. Protein phosphatase ---------------------------------------- 11. What is the source of fructosamine formation through glycation? A. Fructose B. Albumin C. Urea D. Glycosaminoglycan ---------------------------------------- 12. What is the cause of Pompe disease? A. Lysosomal acid alpha glucosidase B. β-hexosaminidase-A C. β–galactocerebrosidase D. β-glucocerebrosidase ---------------------------------------- 13. Which of the following glycosaminoglycans (GAGs) are responsible for corneal transparency? A. Keratan sulfate B. Chondroitin sulfate C. Heparin sulfate D. Hyaluronic acid ---------------------------------------- 14. In this scenario, what is the origin of the blood glucose measured at 7 am the following morning for an individual who had dinner at 8 pm the previous night? A. Hepatic glycogenolysis B. Hepatic gluconeogenesis C. Muscle glycogenolysis D. Dietary glucose ---------------------------------------- 15. In the diagram provided, which enzymes are identified as E1 and E2, responsible for the conversion of pyruvate to acetyl CoA? Page 3 141 A. Pyruvate dehydrogenase and dihydrolipoyl transacetylase B. Pyruvate carboxylase and dihydrolipoyl transacetylase C. Pyruvate dehydrogenase and dihydropoyl dehydrogenase D. Pyruvate carboxylase and dihydrolipoyl dehydrogenase ---------------------------------------- 16. Gluconeogenesis is inhibited by A. Insulin B. Glucagon C. Lactate D. None of above ---------------------------------------- 17. Which specific glucose transporter is present in the skeletal muscle? A. GLUT 1 B. GLUT 2 C. GLUT 3 D. GLUT 4 ---------------------------------------- 18. "What is the most frequently occurring amino acid in collagen?" A. Proline B. Lucine C. Arginine D. Glycine ---------------------------------------- 19. Which is the enzyme activated by a decrease in insulin: glucagon ratio? A. Glucokinase B. Hexokinase C. Phosphofructokinase Page 4 142 D. Glucose 6-phosphatase ---------------------------------------- 20. Which enzyme is responsible for the deficiency causing classical galactosemia? A. Aldose reductase B. Galactokinase C. Galactose-1-phosphate uridyl transferase D. UDP galactose-4-epimerase ---------------------------------------- 21. Which one of the following choices does not represent a function of glucagon? A. Glycolysis B. Gluconeogenesis C. Glycogenolysis D. Ketogenesis ---------------------------------------- 22. A 10-year-old boy rapidly develops hypoglycemia after moderate activity. Blood examination reveals raised levels of ketone bodies, lactic acid, and triglycerides. On examination, the liver and kidneys are found to be enlarged. Which of the following deficiencies would be seen in the liver of this child? A. Glucose-6-phosphate B. Glucose-1-phosphate C. Glucose-1,6-diphosphate D. Glycosaminoglycans ---------------------------------------- 23. What is the primary source of reducing equivalents for liver fatty acid synthesis? A. Hexose monophosphate shunt pathway B. Glycolysis C. Tricarboxylic acid cycle D. Uronic acid pathway ---------------------------------------- 24. Which one of the options provided does not serve as a substrate for the synthesis of glucose? A. Acetyl coenzyme A B. Glycerol C. Alanine D. Lactate ---------------------------------------- 25. What is the main substrate and metabolic fuel used by RBCs during fasting period? Page 5 143 A. Ketone bodies B. Glucose C. Free fatty acids D. Amino acids ---------------------------------------- 26. Which of the following diagnostic markers is/are not correctly matched? 1. Beta glucocerebrosidase Von Gierke disease 2. Lipase Acute pancreatitis 3. Ceruloplasmin Hepatolenticular degeneration 4. High LDH1: LDH2 ratio Myocardial infarction 1. Beta glucocerebrosidase Von Gierke disease 2. Lipase Acute pancreatitis 3. Ceruloplasmin Hepatolenticular degeneration 4. High LDH1: LDH2 ratio Myocardial infarction A. 1 only B. 1 and 2 C. 1, 2 and 4 D. 2, 3 and 4 ---------------------------------------- 27. Does Von Gierke's disease result in an enzyme deficiency? A. Liver phosphorylase B. Lysosomal glucosidase C. Hepatic glycogen synthase D. Glucose 6-phosphatase ---------------------------------------- 28. Which enzyme is likely to be deficient in a 4-year-old child who presents with a habit of biting their lips and fingers, and has a missing portion of fingers on their left hand? Further evaluation shows delayed developmental milestones. The parents report that two male cousins on the mother's side have similar symptoms and have been diagnosed with a genetic disorder. Laboratory reports indicate hyperuricemia. A. Purine nucleoside phosphorylase B. Hypoxanthine -guanine phosphoribosyl transferase C. Adenine phosphoribosyl transferase D. Adenosine deaminase ---------------------------------------- 29. A newborn baby refuses breast milk since the 2nd day of birth but accepts glucose water. He develops vomiting and severe jaundice by the 5th day. Benedict’s test was positive for urine, and blood glucose was low. The most likely cause is due to the deficiency of: A. Aldose reductase B. Galactokinase Page 6 144 C. Galactose-1-phosphate uridyl transferase D. UDP galactose-4- epimerase ---------------------------------------- 30. Which of the following is the best screening investigation for metabolic disorders? A. Western blot B. Tandem mass spectrometry C. PCR D. Gel electrophoresis ---------------------------------------- 31. Which metabolic pathway is hindered by Fluoroacetate, a constituent found in pesticides? A. TCA cycle B. Glycolytic pathway C. Oxidative phosphorylation D. ETC ---------------------------------------- 32. If an individual is following a diet solely comprised of carbohydrates, what would be the respiratory quotient? A. 0.7 B. 0.8 C. 1 D. 1.2 ---------------------------------------- 33. The best method to measure HbA1C is --- A. Isoelectric focusing B. Affinity chromatography C. Ion exchange chromatography D. Electrophoresis ---------------------------------------- 34. Which of the following enzymes are involved in gluconeogenesis? A. Pyruvate carboxylase B. Phosphoenol pyruvate kinase C. Hexokinase D. Pyruvate kinase E. Glucose 6 phosphatase A. A, B and E only B. B and C only C. A and E only D. A, B and C only ---------------------------------------- 35. The infant is suffering from which of the following abnormalities? Page 7 145 A. Snowflake cataract B. Oil drop cataract C. Her’s disease D. Von gierke’s disease ---------------------------------------- 36. Which glycogen storage disease is associated with the alkaline pH of skeletal muscle after strenuous exercise? A. Mc Ardle's disease B. Von — Gierke's disease C. Her's disease D. Pompe's disease ---------------------------------------- 37. What is the enzyme that is shared by both glycolysis and gluconeogenesis? A. Pyruvate kinase B. Phosphofructokinase C. Phosphoenolpyruvate carboxy kinase D. Phosphoglycerate kinase ---------------------------------------- 38. Ketosis is common in type 1 DM due to: Decreased beta-oxidation of fatty acids Increased mobilization of fat from the adipose cell Decreased acetyl CoA in TCA cycle Increase beta-hydroxy butyryl synthase A. 1, 2, and 3 B. 1,2,3 and 4 C. 4 only D. 1 and 2 only ---------------------------------------- 39. Which enzymes show deficiency in Von Gierke's disease? A. Liver glycogen phosphorylase Page 8 146 B. Muscle glycogen phosphorylase C. Glycogen debranching enzyme D. Glucose-6-phosphatase ---------------------------------------- 40. A young boy presents to the OPD with fatigue and muscle cramps, on exertion. Then he becomes normal after resting for a while. These episodes are recurrent after a period of activity. He has decreased serum lactate and glucose levels. Which of the following diseases is he most likely to be suffering from? A. McArdle disease B. Hers disease C. Cori's disease D. Pompe's disease ---------------------------------------- Correct Answers Question Correct Answer Question 1 3 Question 2 1 Question 3 1 Question 4 2 Question 5 1 Question 6 3 Question 7 2 Question 8 1 Question 9 2 Question 10 1 Question 11 2 Question 12 1 Question 13 1 Question 14 1 Question 15 1 Question 16 1 Question 17 4 Question 18 4 Question 19 4 Question 20 3 Page 9 147 Question 21 1 Question 22 1 Question 23 1 Question 24 1 Question 25 2 Question 26 1 Question 27 4 Question 28 2 Question 29 3 Question 30 2 Question 31 1 Question 32 3 Question 33 3 Question 34 3 Question 35 2 Question 36 1 Question 37 4 Question 38 1 Question 39 4 Question 40 1 Solution for Question 1: Correct Option C: Primaquine is a drug frequently prescribed to treat malaria brought on by Plasmodium ovale and Plasmodium vivax. It functions by interfering with the malarial parasite's Hexose monophosphate (HMP) pathway, which causes an accumulation of harmful metabolites that eventually kills the parasite. However, the Hexose monophosphate (HMP) pathway is also crucial for producing NADPH, which is required for the cellular antioxidant defense system and for the regeneration of reduced glutathione, in human red blood cells. In reaction to oxidative stress, hemolytic anemia can result from a deficit of the enzyme glucose-6-phosphate dehydrogenase (G6PD), which is implicated in the HMP pathway. It is likely that the patient's hemolytic anemia was caused by an underlying G6PD deficiency that was brought on by the use of primaquine. This is a well-known adverse effect of primaquine therapy in G6PD deficient patients. Therefore, the deficiency of an enzyme is involved in the Hexose monophosphate (HMP) pathway. Page 10 148 Incorrect Options: Option A. Glycolysis: The metabolic process known as glycolysis turns glucose into pyruvate while also producing ATP and NADH. Glycolytic enzyme deficits are not frequently linked to hemolytic anemia. Option B. Gluconeogenesis: The metabolic process known as "gluconeogenesis" produces glucose from non-carbohydrate precursors such lactate, glycerol, and amino acids. Hypoglycemia can result from gluconeogenic enzyme deficiencies, however hemolytic anemia is rarely a side effect. Option D. Luebering-Rapoport pathway: The 2,3-bisphosphoglycerate (2,3-BPG) produced by the Luebering-Rapoport route, a metabolic mechanism in red blood cells, aids in the release of oxygen from hemoglobin. Hemolytic anemia is not often linked to deficiencies in the enzymes that make up this pathway. Solution for Question 2: Correct Option A: A rare genetic condition known as McArdle disease, or myophosphorylase deficiency, affects how the body uses glycogen for energy. When energy is required, glycogen, a complex carbohydrate stored in the muscles and liver, is converted into glucose. In muscle tissue, the enzyme myophosphorylase aids in the conversion of glycogen to glucose-1-phosphate. Myophosphorylase insufficiency results in the absence or improper activity of this enzyme. Exercise intolerance is the outcome of this inability to break down the glycogen in muscle tissue. Page 11 149 Muscle cramps, stiffness, and weakness are common signs of exercise intolerance in patients with myophosphorylase deficiency. The sensations typically appear minutes after beginning exercise, and a brief period of rest can help to alleviate them. Therefore, myophosphorylase enzyme deficiencies could be the cause of cramps on exertion. Incorrect Options: Option B. Hexokinase: The conversion of glucose to glucose-6-phosphate, the initial step in glycolysis, is catalyzed by hexokinase. This insufficiency would lead to a reduction in glucose uptake and could result in symptoms like exhaustion and weakness, but not exercise intolerance or cramps while exerting oneself. Option C. Glucose-6-phosphatase: The final stage in gluconeogenesis and glycogenolysis, the conversion of glucose-6-phosphate to glucose, is carried out by glucose-6-phosphatase. This deficiency would produce hypoglycemia and poor liver glucose release, but not exercise intolerance or cramping while exerting oneself. Option D. Hepatic glycogen phosphorylase: While myophosphorylase is in charge of breaking down glycogen in muscle tissue, hepatic glycogen phosphorylase is in charge of doing so in the liver. Therefore, a hepatic glycogen phosphorylase deficiency would primarily impact the liver and not cause exercise intolerance or cramping when exerting oneself. Solution for Question 3: Correct Option A: Gaucher disease, a lysosomal storage condition brought on by a lack of the enzyme glucocerebrosidase, is consistent with the symptoms and signs that are currently present, including Page 12 150 anemia, thrombocytopenia, bone pain, and hepatosplenomegaly. A sphingolipid found in cellular membranes called glucocerebroside is broken down by the enzyme glucocerebrosidase. Hepatosplenomegaly, anemia, thrombocytopenia, and bony pain are all symptoms of Gaucher disease, which is caused by the buildup of glucocerebroside in cells, mainly in the liver, spleen, and bone marrow. A defining feature of Gaucher disease is the "crumpled tissue paper" appearance on light microscopy of bone marrow aspirate. Gaucher cells, which are Lipid laden macrophages. Therefore, the enzyme effect is called Glucocerebrosidase. Incorrect Options: Option B. Sphingomyelinase: Niemann-Pick disease, which can also manifest as hepatosplenomegaly, anemia, and thrombocytopenia, is caused by a deficiency in this enzyme. In contrast to the "crumpled tissue paper" appearance, the bone marrow findings in Niemann-Pick disease typically consist of foamy histiocytes Page 13 151 macrophages with lipid-filled cytoplasm. Foam cells (Lipid laden macrophage) Cherry red spots on macula Progressive neurodegenerative condition In contrast to the "crumpled tissue paper" appearance, the bone marrow findings in Niemann-Pick disease typically consist of foamy histiocytes macrophages with lipid-filled cytoplasm. Foam cells (Lipid laden macrophage) Cherry red spots on macula Progressive neurodegenerative condition In contrast to the "crumpled tissue paper" appearance, the bone marrow findings in Niemann-Pick disease typically consist of foamy histiocytes macrophages with lipid-filled cytoplasm. Foam cells (Lipid laden macrophage) Cherry red spots on macula Progressive neurodegenerative condition Option C. Hexosaminidase: Tay-Sachs disease, Lysosomal storage illness that can induce hepatosplenomegaly but normally does not result in anemia, thrombocytopenia, or bone discomfort, has a deficiency in this enzyme. Progressive neurodegeneration and developmental delay. Hyperreflexia Hyperacusis Cherry red spots on macula In Tay-Sachs disease, the bone marrow findings might have a "onion skin" appearance but not "crumpled tissue paper" appearance. Lysosomal storage illness that can induce hepatosplenomegaly but normally does not result in anemia, thrombocytopenia, or bone discomfort, has a deficiency in this enzyme. Progressive neurodegeneration and developmental delay. Hyperreflexia Hyperacusis Cherry red spots on macula In Tay-Sachs disease, the bone marrow findings might have a "onion skin" appearance but not "crumpled tissue paper" appearance. Lysosomal storage illness that can induce hepatosplenomegaly but normally does not result in anemia, thrombocytopenia, or bone discomfort, has a deficiency in this enzyme. Progressive neurodegeneration and developmental delay. Hyperreflexia Hyperacusis Cherry red spots on macula In Tay-Sachs disease, the bone marrow findings might have a "onion skin" appearance but not "crumpled tissue paper" appearance. Option D. Glucose6-phosphatase: Glycogen storage disease type I (von Gierke disease), which can induce hepatosplenomegaly and bone pain but normally does not cause anemia or thrombocytopenia, is caused by a deficiency in this enzyme. Von Gierke illness may result in an increase in glycogen-containing cells, but not the look of "crumpled tissue paper" in the bone marrow. Page 14 152 Findings are severe fasting hypoglycemia, increase glycogen in liver and kidney, increase lactate, increase triglyceride and increase uric acid. Deficiency of glucose 6 phosphate. Treatment: Frequent oral glucose and avoid fructose and galactose. Impaired gluconeogenesis and glycogenolysis. Solution for Question 4: Explanation: Gluconeogenesis is a metabolic process in the body in which glucose is produced from a non-carbohydrate substrate of carbon. Glycogenolysis is biochemical process in which glycogen is broken down into glucose and glucose-1-phosphate. During the fasting state, glucose is produced from glycogen in the liver which is called glycogenolysis and also via gluconeogenesis from glycerol and oxaloacetate. Incorrect Choices: a. Glycolysis is a chain of reactions that produce energy from glucose by breaking into two molecules of three carbon molecule compounds called pyruvates. Hence, this is incorrect. c. Glycogenesis is formation of glycogen from primary carbohydrate that is stored in the muscle, liver cells of animals from the glucose molecule. Hence, this is incorrect. d. Gluconeogenesis and glycogenolysis are both pathways used in the production of glucose during the fast. Solution for Question 5: Correct Option A: Von Gierke's disease, or glycogen storage disease type Ia, is a rare genetic disorder characterized by the deficiency of glucose-6-phosphatase. This enzyme plays a key role in gluconeogenesis and glycogenolysis. It cleaves a phosphate group from glucose-6-phosphate to generate glucose, which is then released into the bloodstream to maintain normal blood sugar levels. Without glucose-6-phosphatase, glycogen accumulates in the liver and kidneys, leading to hepatomegaly, hypertriglyceridemia, and hypoglycemia. Therefore, the enzyme found to be deficient in Von Gierke's disease is glucose-6-phosphatase. Page 15 153 Incorrect Options: Option B - Branching enzyme: Branching enzyme is an enzyme that plays a key role in glycogen synth esis. It forms the branching points that allow glycogen to compactly store glucose. Mutations in the bra nching enzyme gene can lead to glycogen storage disease type IV, characterized by accumulating a poorly branched glycogen molecule. Option C - Debranching enzyme: Debranching enzyme is an enzyme that plays a key role in glycogen breakdown. It is responsible for removing the branches of glycogen to generate glucose-1-phosphate, which can then be converted to glucose-6-phosphate for further metabolism. Deficiencies in debranchi ng enzymes can lead to glycogen storage disease type III, characterized by accumulating a poorly branched glycogen molecule. Option D - Muscle glycogen phosphorylase: Muscle glycogen phosphorylase is an enzyme that plays a key role in glycogen breakdown in muscle cells. It is responsible for breaking down glycogen into gluco se-1-phosphate, which is then converted to glucose-6-phosphate for further metabolism. Mutations in t he muscle glycogen phosphorylase gene can lead to glycogen storage disease type V, also known as McArdle disease, characterized by muscle weakness and cramping. Solution for Question 6: Correct Option C: Glycolysis is the only metabolic pathway among the four that exclusively occurs in the cytoplasm of both eukaryotic and prokaryotic cells. Glycolysis is a central pathway of cellular metabolism and is the primary energy source for many cell types. The process involves the breakdown of glucose into pyruvate, which can then be further processed to produce ATP. Incorrect Options: Option A - Beta oxidation: It is a metabolic process by which fatty acids are broken down into acetyl-Co A molecules, which can then enter the TCA cycle to produce ATP. This process occurs in the mitochon dria of eukaryotic cells, where enzymes responsible for beta-oxidation are located in the mitochondrial Page 16 154 matrix and inner membrane. Option B - TCA cycle: Also known as the citric acid cycle or Krebs cycle, is a series of metabolic reacti ons in eukaryotic cells’ mitochondria. The cycle generates ATP molecules from the breakdown of carbo hydrates, fats, and proteins. Many enzymes involved in the TCA cycle are located in the mitochondrial matrix, while others are embedded in the inner membrane. Option D - Urea cycle: It is a metabolic pathway that occurs in the liver of animals and some microorga nisms. It involves the conversion of ammonia, a toxic waste product of protein metabolism, into urea, w hich is less toxic and can be excreted in the urine. The enzymes responsible for the urea cycle are loca ted in both the cytoplasm and mitochondria of liver cells. Solution for Question 7: Correct Option B - Glycogen synthase: The patient presents with exercise intolerance, hypoglycemia, and an absence of glycogen in the liver. The most likely deficient enzyme is glycogen synthase and is also known as glycogen storage disorder type 0. Glycogen synthase acts on UDP glucose and converts it into glycogen primer in the liver and muscles thus helping in the storage of glucose. When this enzyme is deficient, no glycogen is formed, and no glucose is released in the fasting state, leading to hypoglycemia between meals and exercise intolerance occurs due to the absence of glycogen in muscles. Incorrect Options: Option A - Branching Enzyme: Deficiency of branching enzyme typically leads to a specific glycogen st orage disease called glycogen storage disease type IV (Anderson disease), characterized by accumula tion of the glycogen without branches (abnormal glycogen) in the liver and presents with hepatomegaly leading to liver cirrhosis. Option C - Debranching enzyme: Deficiency of the debranching enzyme typically leads to a specific gly cogen storage disease called glycogen storage disease type III (also known as Cori disease), characte rized by exercise intolerance, hypoglycemia, and an abnormal glycogen with multiple branches will acc umulate. Option D - Glucose 6 phosphatase: Deficiency of glucose 6 phosphatase results in glycogen storage disease type I (also known as von Gierke disease), characteri zed by hypoglycemia, doll-like facies, xanthoma, ketosis, and hepatomegaly. Solution for Question 8: The condition being described is Wilson's disease, an inherited disorder characterized by the abnormal accumulation of copper in various tissues, including the liver, brain, and eyes. Thus, copper is respons ible for this condition. In Wilson's disease, there is a defect in the transport of copper, leading to its buildup in the liver and subsequent release into the bloodstream. Excess copper is then deposited in various organs, including the eyes. Page 17 155 The copper deposition in the eyes can cause a characteristic finding called Kayser-Fleischer rings, which are golden-brown to greenish-brown rings seen around the cornea. The accumulation of copper in the liver can damage the liver, resulting in hepatocellular dysfunction, inflammation, and fibrosis. This can manifest as hepatomegaly (enlarged liver), jaundice, fatigue, and other symptoms of liver dysfunction. Incorrect Choices: Option b. Glucose is not responsible for the condition described. Glucose is a simple sugar and the body’s primary energy source. While liver damage can occur due to various causes, glucose itself is not a direct factor responsible for liver damage in this scenario. Option c. Galactose is not responsible for the condition described. Galactose is a sugar found in milk and dairy products. Galactosemia is a rare genetic disorder characterized by the inability to metabolize galactose, leading to its accumulation in the body. However, galactose is not directly associated with the liver damage described in the question. Option d. Mannose is not responsible for the condition described. Mannose is a sugar that plays a role in glycoprotein synthesis and cellular communication. However, it is not associated with the specific liver damage depicted in the question Solution for Question 9: In sickle cell anemia, there is a single-point mutation in the gene encoding the beta-globin subunit of hemoglobin. This mutation leads to the substitution of glutamic acid by valine at the 6th position of the beta-globin chain. Normal hemoglobin, known as hemoglobin A (HbA), consists of two alpha-globin chains and two beta-globin chains. In sickle cell anemia, the mutation causes the production of abnormal hemoglobin called hemoglobin S (HbS). The substitution of glutamic acid for valine at the 6th position alters the physical properties of hemoglobin. Under certain conditions, such as low oxygen tension, HbS molecules can polymerize and form long, rigid fibers inside the red blood cells (RBCs). This polymerization leads to the characteristic sickle shape of RBCs and results in decreased flexibility and increased fragility of the cells. The sickle-shaped RBCs can get stuck in small blood vessels, leading to vaso-occlusive crises and causing pain, organ damage, and various complications associated with sickle cell anemia Incorrect Choices: Option a: In sickle cell anemia, there is a substitution of glutamic acid, not valine, at the 6th position of the beta-globin chain of hemoglobin. Option c: The substitution in sickle cell anemia occurs at the 6th position, not the 5th position. Option d: The substitution in sickle cell anemia occurs at the 6th position, not the 5th position Page 18 156 Solution for Question 10: Correct Option A - Calcium: Glycogen phosphorylase is activated by calcium ions. Calcium ions play a key role in regulating many physiological processes in the body, including muscle contraction, neurotransmitter release, and enzyme activation. In the case of glycogen phosphorylase, calcium ions bind to a regulatory protein called calmodulin, which activates an enzyme called phosphorylase kinase. Phosphorylase kinase, in turn, activates glycogen phosphorylase by phosphorylating it. This allows glycogen to be broken down into glucose-1-phosphate, which can be used by cells for energy. Incorrect Options: Option B, C and D are incorrect Solution for Question 11: Correct Option B - Albumin: Fructosamine is formed by the non-enzymatic glycation of serum albumin, which is the most abundant protein in the blood. Serum albumin has a long half-life, and the level of fructosamine in the blood can serve as a useful clinical marker of glycemic control over a period of several weeks. The formation of fructosamine occurs through the reaction of the amino groups of lysine and other amino acids in serum albumin with reducing sugars, such as glucose or fructose. Incorrect Options: Options A, C and D are not involved in the formation of fructosamine. Solution for Question 12: Correct Option A: Lysosomal acid alpha glucosidase Pompe disease, also known as Glycogen Storage Disease Type II, is caused by a deficiency of the enzyme lysosomal acid alpha glucosidase (also called acid maltase or acid alpha-glucosidase). This enzyme is responsible for breaking down glycogen, a complex sugar molecule, into glucose within the lysosomes of cells. The breakdown of glycogen is crucial for providing a source of energy for cells. In Pompe disease, the deficiency or malfunction of lysosomal acid alpha glucosidase leads to the accumulation of glycogen within various tissues and organs, particularly in skeletal and cardiac muscles. This buildup of glycogen impairs the normal function of these tissues, resulting in the signs and symptoms associated with Pompe disease. Incorrect Options The other enzymes mentioned in the options are associated with different disorders: Option B: β-hexosaminidase-A: Deficiency of this enzyme is seen in Tay-Sachs disease, a rare inherited disorder that affects the central nervous system. Page 19 157 Option C: β-galactocerebrosidase: Deficiency of this enzyme is seen in Krabbe disease, an autosomal recessive disorder characterized by the accumulation of a fatty substance called galactocerebroside. Option D: β-glucocerebrosidase: Deficiency of this enzyme is seen in Gaucher disease, a lysosomal storage disorder characterized by the accumulation of glucocerebroside in cells. In summary, Pompe disease is caused by a deficiency of lysosomal acid alpha glucosidase. Solution for Question 13: Correct Option A: Corneal transparency is maintained by a well-organized arrangement of collagen fibers and the presence of specific glycosaminoglycans (GAGs) within the cornea. GAGs are long, unbranched polysaccharides composed of repeating disaccharide units. They contribute to the hydration, structure, and function of various tissues. Keratan sulfate is a type of GAG that is specifically responsible for maintaining corneal transparency. It is predominantly found within the cornea and helps to regulate the spacing and alignment of collagen fibrils, allowing light to pass through the cornea without significant scattering. Keratan sulfate interacts with collagen and other proteoglycans to form a specialized matrix that provides transparency and structural integrity to the cornea. Incorrect Options: Option B: Chondroitin sulfate: Chondroitin sulfate is a GAG found in various connective tissues, such a s cartilage and tendons. While it plays an important role in these tissues, it is not primarily responsible f or corneal transparency. Option C: Heparin sulfate: Heparin sulfate is a GAG that is found in various tissues and acts as an anti coagulant. It has diverse functions in different organs but is not specifically associated with corneal tran sparency. Option D: Hyaluronic acid: Hyaluronic acid is a GAG that is widely distributed in various tissues and is i nvolved in multiple biological processes. While it is present in the cornea and contributes to its hydratio n and viscoelastic properties, it is not the primary GAG responsible for maintaining corneal transparenc y. Solution for Question 14: Correct Option A: Hepatic glycogenolysis refers to the breakdown of glycogen stored in the liver into gl ucose. During periods of fasting or between meals, when the body requires a steady supply of glucose to maintain blood glucose levels, the liver plays a crucial role in releasing gluc ose into the bloodstream through glycogenolysis. The glycogen stored in the liver is broken down into g lucose-6-phosphate and subsequently converted into glucose, which is then released into the bloodstre am. Incorrect Options: Option B: Hepatic gluconeogenesis: Hepatic gluconeogenesis refers to the synthesis of glucose from n on-carbohydrate sources, such as amino acids, lactate, or glycerol. While gluconeogenesis can contrib ute to maintaining blood glucose levels during prolonged fasting or in certain metabolic states, it is not t he primary source of blood glucose immediately after a meal. Page 20 158 Option C: Muscle glycogenolysis: Muscle glycogenolysis refers to the breakdown of glycogen stored in muscle tissue. While muscle glycogen can be broken down to provide glucose for energy within the mu scle cells, it does not significantly contribute to blood glucose levels. Option D: Dietary glucose: Dietary glucose refers to the glucose obtained directly from the ingestion of carbohydrates in the diet. However, in this case, the person has tested their blood glucose levels after f asting overnight, so the contribution of dietary glucose to blood glucose at this specific time would be m inimal. Solution for Question 15: Correct Option A: The conversion of pyruvate to acetyl CoA is a key step in cellular respiration and occurs in the mitochondria. It involves a multi-enzyme complex called the pyruvate dehydrogenase complex (PDC). The enzymes marked as E1 and E2 in the diagram correspond to specific components of the PDC: Incorrect Options: Option B: Pyruvate carboxylase and dihydrolipoyl transacetylase: Pyruvate carboxylase is involved in a different metabolic pathway called gluconeogenesis, where it converts pyruvate into oxaloacetate. It is not directly involved in the conversion of pyruvate to acetyl CoA. Option C: Pyruvate dehydrogenase and dihydropoyl dehydrogenase: There is no enzyme called "dihyd ropoyl dehydrogenase" involved in the conversion of pyruvate to acetyl CoA. The correct enzyme invol ved in transferring electrons in the PDC is dihydrolipoyl dehydrogenase. Solution for Question 16: Page 21 159 Correct option: Option: A Insulin Insulin inhibits gluconeogenesis, which is the process of synthesizing glucose from non-carbohydrate s ources such as amino acids, lactate, and glycerol. When insulin levels are high, such as in the fed stat e, it signals that there is sufficient glucose available for energy metabolism, and there is no need to pro duce additional glucose. Insulin promotes glucose uptake by cells, increases glycogen synthesis, and i nhibits the breakdown of glycogen (glycogenolysis) and gluconeogenesis. Incorrect options: Option B. Glucagon, on the other hand, stimulates gluconeogenesis. Glucagon is released when blood glucose levels are low, signaling a need to produce glucose to maintain an adequate energy supply. Gl ucagon promotes the breakdown of glycogen to release glucose (glycogenolysis) and stimulates gluco neogenesis to generate glucose from non-carbohydrate sources. Option C. Lactate can be converted into pyruvate through a process called lactate conversion, and pyr uvate can be further used in gluconeogenesis. Therefore, lactate can contribute to gluconeogenesis un der certain conditions, such as during exercise or in the liver. Option D. None of the above is incorrect Solution for Question 17: Correct option : Option D. GLUT 4 is the glucose transporter that is primarily found in skeletal muscle cells, as well as adipose tis sue. It plays a crucial role in the uptake of glucose from the bloodstream into these target tissues. Incorrect options : Option A. GLUT 1 is a glucose transporter found in various tissues, including red blood cells, the brain, and endothelial cells. It facilitates the basal uptake of glucose in these cells. Option B. GLUT 2 is mainly found in the liver, pancreas, and small intestine. It has a role in glucose upt ake and release in these organs, such as the uptake of glucose from the intestine and the release of gl ucose from the liver. Option C. GLUT 3 is predominantly expressed in neurons and is responsible for glucose transport acro ss the blood-brain barrier. It ensures a constant supply of glucose to meet the high energy demands of the brain. Solution for Question 18: Correct option : Option D. The most common amino acid found in collagen is Glycine. Glycine makes up approximately one-third of the amino acids in the collagen protein. Its small size allows for the close packing of collagen helices , contributing to the structural stability of collagen. Page 22 160 Incorrect options: Option A. Proline: Proline is also present in collagen, but it is not the most common amino acid. Proline plays a crucial role in the formation of collagen helices by introducing kinks in the protein structure. Option B. Leucine: Leucine is not the most common amino acid in collagen. Leucine is a hydrophobic amino acid and is not typically abundant in collagen. Option C. Arginine: Arginine is present in collagen but is not the most common amino acid. Arginine re sidues in collagen contribute to the formation of intermolecular cross-links, which enhance the stability and tensile strength of collagen fibers. Solution for Question 19: Correct Option: D Glucose 6-phosphatase: Glucose 6-phosphatase is an enzyme primarily found in the liver and kidney. It plays a crucial role in glucose metabolism by catalyzing the hydrolysis of glucose 6-phosphate to free glucose and inorganic phosphate. This enzyme is responsible for the final step in gluconeogenesis and glycogenolysis, where glucose is released into the bloodstream. During times of decreased insulin and increased glucagon, such as fasting or low blood sugar, glucagon stimulates the activation of glucose 6-phosphatase, increasing glucose production. Incorrect options: Option A. Glucokinase: Glucokinase is an enzyme primarily found in the liver and pancreas. It catalyze s the phosphorylation of glucose to form glucose 6-phosphate, an important step in glycolysis and glyc ogen synthesis. The glucokinase activity decreases with a decrease in the insulin: glucagon ratio. Option B. Hexokinase: Hexokinase is an enzyme found in various tissues. It also catalyzes the phosph orylation of glucose to form glucose 6-phosphate. The hexokinase activity decreases with a decrease in the insulin: glucagon ratio. Option C. Phosphofructokinase: Phosphofructokinase is an enzyme involved in regulating glycolysis, s pecifically the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate. A decrease in the insul in: glucagon ratio decreases its activity. Phosphofructokinase activity is regulated by various factors, in cluding ATP, ADP, and citrate concentration. Solution for Question 20: Correct option C: Galactose-1-phosphate uridyl transferase Classical Galactosemia is due to the deficiency of the enzyme Galactose-1-phosphate uridyl transferase (GALPUT). It is a rare congenital autosomal recessive disorder. In this condition, galactose levels are increased in circulation and urine. The accumulated galactose-1-phosphate is converted into dulcitol by the enzyme aldose reductase. This accumulation of Dulcitol is associated with the development of cataracts., and impairment of organs such as the liver and kidney. Incorrect options: Option A: Aldose reductase: This enzyme is responsible for the conversion of the already accumulated Galactose-1-phosphate in the cells into dulcitol. Its deficiency does not cause classic Galactosemia. Page 23 161 Option B: Galactokinase: This enzyme is responsible for the conversion of galactose to galactose-1-ph osphate. The deficiency of galactokinase causes Galactosemia type II. Option D: UDP galactose-4-epimerase: This enzyme is responsible for the conversion of UDP-Galacto se to UDP-Glucose. The deficiency of this enzyme causes a rare condition called epimerase deficiency galactosemia. Solution for Question 21: Correct option A: Glycolysis Glucagon is a hormone secreted by the alpha cells of islets of Langerhans in the pancreas. This hormone is responsible for regulating the blood glucose level. Glucagon does not play a role in Glycolysis which is the process of breakdown of glucose as it reduces blood glucose levels. On the contrary, glucagon increases the synthesis of glucose (gluconeogenesis) and the breakdown of glycogen in the liver to release glucose (Glycogenolysis). The levels of Glucagon in blood increase in fasting state. Incorrect options: Option B: Gluconeogenesis: This is the synthesis of glucose from non-carbohydrate sources in the liver. Glucagon acts on the liver and promotes gluconeogenesis. This causes an increase in blood glucose levels. Option C: Glycogenolysis: This is the process of breakdown of glycogen in the liver to produce glucose. This process is promoted by glucagon. Option D: Ketogenesis: Glucagon promotes the breakdown of fatty acids to produce ketone bodies. Thi s process is called Ketogenesis. Solution for Question 22: Correct option A: Glucose-6-phosphate The given features are consistent with the diagnosis of VON GIERKE DISEASE. In this disease, there is a deficiency of the enzyme glucose 6 phosphatase. It is the most common glycogen storage disorder. Features include: Severe Hypoglycemia Doll-like faces Xanthomas Ketosis Lactate acidosis Hyperuricemia Severe Hypoglycemia Doll-like faces Xanthomas Ketosis Lactate acidosis Hyperuricemia Severe Hypoglycemia Doll-like faces Page 24 162 Xanthomas Ketosis Lactate acidosis Hyperuricemia Incorrect options: Option B: Glucose-1-phosphate reacts in the presence of phosphorylase with aldoses and ketoses to yi eld disaccharides and ultimately produce glycogen and phosphoric acid. Also called Cori ester. Option C: Glucose-1,6-diphosphate is the central regulator in glycogen metabolism, glycolysis, amino s ugar formation as well as bacterial cell wall and capsule formation. Option D: Glycosaminoglycans are heteropolysaccharides and consist of various sulfate-free and sulfat e-containing compounds. Glycosaminoglycans play an important role in cell signaling and development , angiogenesis, anti-coagulation, tumor progression, axonal growth, and metastasis. Solution for Question 23: Correct option A: Hexose monophosphate shunt pathway is the primary source of reducing equivalents for liver fatty acid synthesis It does not generate ATP but has two major functions: The formation of NADPH for the synthesis of fatty acids and steroids The synthesis of ribose for nucleotide and nucleic acid formation The pentose phosphate pathway is active in the liver, adipose tissue, adrenal cortex, thyroid, erythrocytes, testis, and lactating mammary gland. Its activity is low in the non-lactating mammary gland and skeletal muscle. Those tissues in which the pathway is active use NADPH in reductive synthesis, eg, of fatty acids, steroids, amino acids via glutamate dehydrogenase, and reduced glutathione. The formation of NADPH for the synthesis of fatty acids and steroids The synthesis of ribose for nucleotide and nucleic acid formation The pentose phosphate pathway is active in the liver, adipose tissue, adrenal cortex, thyroid, erythrocytes, testis, and lactating mammary gland. Its activity is low in the non-lactating mammary gland and skeletal muscle. Those tissues in which the pathway is active use NADPH in reductive synthesis, eg, of fatty acids, steroids, amino acids via glutamate dehydrogenase, and reduced glutathione. The formation of NADPH for the synthesis of fatty acids and steroids The synthesis of ribose for nucleotide and nucleic acid formation The pentose phosphate pathway is active in the liver, adipose tissue, adrenal cortex, thyroid, erythrocytes, testis, and lactating mammary gland. Its activity is low in the non-lactating mammary gland and skeletal muscle. Those tissues in which the pathway is active use NADPH in reductive synthesis, eg, of fatty acids, steroids, amino acids via glutamate dehydrogenase, and reduced glutathione. Incorrect options: Option B: Glycolysis: Glucose is metabolized to pyruvate by the pathway of glycolysis, which can occur anaerobically (in the absence of oxygen) when the end product is lactate. Glycolysis is the cytosolic pa thway of all mammalian cells for the metabolism of glucose (or glycogen) to pyruvate and lactate. Page 25 163 Option C: Tricarboxylic acid cycle: The citric acid cycle is the final common pathway for the aerobic oxi dation of carbohydrates, lipids, and proteins because glucose, fatty acids, and most amino acids are m etabolized to acetyl-CoA or intermediates of the cycle. Option D: Uronic acid pathway: In the liver, the uronic acid pathway catalyzes the conversion of glucos e to glucuronic acid, ascorbic acid, and pentoses. It is also an alternative oxidative pathway for glucose but does not lead to the generation of ATP. Solution for Question 24: Substrates of gluconeogenesis are mostly 3C compounds including any TCA cycle intermediate. Acetyl COA is not a TCA cycle intermediate, it is a part of a link reaction so it cannot act as a substrate for gluconeogenesis. On the other hand, glycerol, alanine, and lactate are all amino acids that participate in the Krebs cycle and can generate glucose. Incorrect Choices: Option b. Glycerol is a 3C compound which are substrates of gluconeogenesis. Option c. Alanine is a 3C compound that is the substrate of gluconeogenesis. Option d. lactate is a 3C compound that is a substrate of gluconeogenesis. Solution for Question 25: Correct Choice: B RBCs cannot use fatty acid or ketone bodies as fuel during fasting as they do not have mitochondria w here beta-oxidation of fatty acid occurs. Since ketone bodies and free fatty acids are utilized via beta-o xidation which occurs in mitochondria, RBCs cannot utilize them. Therefore, RBC uses glucose as a substrate for energy production in the fed, fasting, and starvation state. Incorrect Choices: Option A: Ketone body: They are used as a substrate for energy production during starvation phase by vital organs brain and heart primarily. Muscles use FA and ketone bodies for energy during starvation t o avoid using proteins as fuel to prevent muscle loss. Option C: Amino acid: It is used by liver as a fuel in starvation state. It is the major source of fuel for the body in a starvation state. Option D: Free fatty acid: It is used as a fuel in fasting state by Heart (uses fatty acid in both fed and fasting state ) Liver Muscle Adipose tissue (uses fatty acid in both fasting and starvation state) Solution for Question 26: Page 26 164 Correct Choice: A Von Gierke disease is a glycogen storage disease. The enzyme deficient is glucose 6 phosphatase present in the liver. Incorrect Choices: Solution for Question 27: Correct Choice. D Explanation: Von Gierke disease is an autosomal recessive disorder in which the body cannot break down glycogen. It is caused by a deficiency of an enzyme named glucose-6-phosphate translocase that releases glucose from glycogen. It transports glucose-6-phosphate into the endoplasmic reticulum for further metabolism. Glucose 6-phosphatase catalyzes the terminal phases of both hepatic gluconeogenesis and glycogenolysis. In glycogen storage disease type 1b (GSD-1b), glucose-6-phosphate accumulates intracellularly. This causes abnormal amounts of glycogen to build up in certain tissues. When glycogen is not broken down properly, it leads to low blood sugar. If a person has this disease, test results will show low blood sugar and high levels of lactate (produced from lactic acid), blood fats (lipids), and uric acid Incorrect Choices: Option A. Liver phosphorylase deficiency is known as Hers disease. Option B. Lysosomal acid α-glucosidase (GAA) deficiency results in Pompe disease, a rare lysosomal storage disease. Option C. Type 0 glycogen storage disease (GSD0) is caused by a deficiency of hepatic glycogen synthase Solution for Question 28: Correct Choice. B Explanation: Hypoxanthine phosphoribosyltransferase (HPRT) deficiency is an X-linked disorder characterized by uric acid overproduction and variable neurologic impairment. The total deficiency of HPRT is diagnostic of Lesch-Nyhan syndrome manifested by choreoathetosis, spasticity, mental retardation, and self-injurious behaviour. Page 27 165 Incorrect Choices: Option A: Purine nucleoside phosphorylase deficiency is not related to Lesch-Nyhan syndrome. Purine nucleoside phosphorylase deficiency is inherited in an autosomal recessive pattern. Option C: Adenine phosphoribosyl transferase is inherited in an autosomal recessive manner. Deficien cy is characterised by excessive production and renal excretion of 2,8-dihydroxyadenine (DHA), which leads to kidney stone formation and crystal-induced kidney damage (i.e., DHA crystal nephropathy). Option D: Adenosine deaminase is inherited in an autosomal recessive pattern. Adenosine deaminase (ADA) deficiency damages the immune system and causes severe combined immunodeficiency (SCID ). Solution for Question 29: Correct Option C: Galactose-1-phosphate uridyl transferase The question presented is a case of galactosemia. This occurs due to the deficiency of galactose-1-phosphate uridyl transferase. Due to the deficiency of galactose-1-phosphate uridyl transferase, there is an excess accumulation of Galactose-1-Phoshate in the liver and brain that causes jaundice, vomiting, hepatomegaly, and mental retardation. Galactosemia is seen mainly in the first week of birth with the symptoms of jaundice. Incorrect Options: Option A - Aldose reductase: Aldose reductase is an enzyme involved in the conversion of glucose to s orbitol. Deficiency of aldose reductase is not associated with the symptoms described in the question, such as refusal of breast milk, vomiting, severe jaundice, positive Benedict's test for urine, and low bloo d glucose levels. Therefore, aldose reductase deficiency is an incorrect option. Option B - Galactokinase: Galactokinase is an enzyme involved in the conversion of galactose to galac tose-1-phosphate. Deficiency of galactokinase leads to a condition known as galactokinase deficiency or galactosemia type II. However, galactokinase deficiency typically presents with symptoms like the pr esence of galactose in the blood and urine, cataracts, and sometimes intellectual disability. It does not typically cause the specific symptoms mentioned in the question, such as refusal of breast milk, severe Page 28 166 jaundice, and low blood glucose levels. Therefore, galactokinase deficiency is an incorrect option. Option D - UDP galactose-4-epimerase: UDP galactose-4-epimerase is an enzyme involved in the con version of UDP-galactose to UDP-glucose. Deficiency of UDP galactose-4-epimerase leads to a conditi on known as epimerase deficiency galactosemia. However, this condition typically presents with sympt oms similar to classic galactosemia, including failure to thrive, hepatomegaly (enlarged liver), jaundice, and developmental delay. It does not typically present with the specific symptoms described in the que stion, such as refusal of breast milk, severe jaundice, and low blood glucose levels. Therefore, UDP ga lactose-4-epimerase deficiency is an incorrect option. Solution for Question 30: Correct Option B: When it comes to screening for metabolic disorders, tandem mass spectrometry (TMS) is considered the best investigation method. TMS is a powerful analytical technique that allows for the detection and quantification of a wide range of metabolites in biological samples. Tandem mass spectrometry involves ionizing and fragmenting molecules in a controlled manner, followed by measuring the mass-to-charge ratios of the resulting ions. By analyzing the patterns of metabolite fragmentation, TMS can identify and quantify specific metabolites associated with various metabolic disorders. Metabolic disorders often involve abnormalities in the metabolism of specific substances, such as amino acids, organic acids, and fatty acids. TMS can detect and measure these metabolites accurately, making it an excellent screening tool for a variety of metabolic disorders. Incorrect options: Option A: Western blot: Western blot is a technique used to detect and analyze specific proteins in a sa mple. While it is valuable for protein analysis and identification, it is not the most suitable method for sc reening metabolic disorders, which primarily involve abnormalities in metabolite levels rather than prote in expression. Option C: PCR (Polymerase Chain Reaction): PCR is a molecular biology technique used to amplify sp ecific DNA sequences. While it is useful for detecting genetic mutations associated with certain metabo lic disorders, it is not the best screening investigation for all metabolic disorders. PCR is more commonl y used for targeted testing when a specific genetic mutation is suspected. Option D: Gel electrophoresis: Gel electrophoresis is a technique used to separate molecules based o n their size and charge. It is commonly used in protein and nucleic acid analysis. While gel electrophor esis can provide valuable information in certain metabolic disorders, it is not as comprehensive or spec ific as tandem mass spectrometry for screening a wide range of metabolic disorders. Solution for Question 31: Correct Option A: Fluoroacetate is a toxic compound that can be found in certain pesticides. It inhibits the TCA cycle, which is a central metabolic pathway involved in the aerobic metabolism of carbohydrates, fats, and amino acids. Page 29 167 In the TCA cycle, acetyl-CoA derived from various fuel sources enters the cycle and undergoes a series of enzymatic reactions to produce energy-rich molecules such as NADH and FADH2. These energy carriers then participate in oxidative phosphorylation and the electron transport chain (ETC) to generate ATP, the cell's primary energy currency. When fluoroacetate enters the cell, it is converted to fluorocitrate, which is structurally similar to citrate, an intermediate in the TCA cycle. Fluorocitrate can competitively inhibit the enzyme aconitase, which is involved in the conversion of citrate to isocitrate in the TCA cycle. By inhibiting aconitase, fluoroacetate disrupts the normal flow of reactions in the TCA cycle, leading to a decrease in ATP production. Incorrect options: Option B: Glycolytic pathway: The glycolytic pathway, also known as glycolysis, is a separate metaboli c pathway that takes place in the cytoplasm of the cell. It involves the breakdown of glucose to produce pyruvate and a small amount of ATP. Fluoroacetate does not directly inhibit the glycolytic pathway. Option C: Oxidative phosphorylation: Oxidative phosphorylation is the process that occurs in the mitoc hondria, where ATP is generated through the transfer of electrons from NADH and FADH2 to the electr on transport chain (ETC). While fluoroacetate indirectly affects oxidative phosphorylation by inhibiting t he TCA cycle, it does not directly target oxidative phosphorylation itself. Option D: ETC (Electron Transport Chain): The electron transport chain is a series of protein complexe s located in the inner mitochondrial membrane. It is responsible for the transfer of electrons and the ge neration of a proton gradient, which drives ATP synthesis. Although fluoroacetate indirectly affects the ETC by inhibiting the TCA cycle, it does not directly target the ETC. Solution for Question 32: Correct Option C: The respiratory quotient (RQ) is the ratio of the volume of carbon dioxide (CO2) produced to the volume of oxygen (O2) consumed during cellular respiration. It represents the substrate being metabolized for energy production. Different substrates, such as carbohydrates, fats, and proteins, have different respiratory quotients due to variations in their chemical composition and metabolic pathways. An exclusive carbohydrate diet means that the individual is only consuming carbohydrates as their source of energy. Carbohydrates are primarily metabolized through aerobic glycolysis and the citric acid cycle (also known as the Krebs cycle) in the mitochondria. During these metabolic processes, carbohydrates are completely oxidized to produce CO2 and water. The stoichiometry of carbohydrate metabolism results in the production of equal amounts of CO2 and O2 consumed. Since the respiratory quotient is the ratio of CO2 produced to O2 consumed, an exclusive carbohydrate diet would result in an RQ of 1. This means that for every molecule of oxygen consumed, an equal number of molecules of carbon dioxide is produced. IIncorrect options: Option A: 0.7: An RQ of 0.7 is typically associated with fat metabolism, as fats require more oxygen co nsumption relative to carbon dioxide production compared to carbohydrates. Option B: 0.8: An RQ of 0.8 is also commonly associated with fat metabolism, as fats have a slightly lower ratio of CO2 production to O2 consumption compared to carbohydrates. Page 30 168 Option D: 1.2: An RQ of 1.2 is not physiologically possible. It would imply more CO2 production than O 2 consumption, which is not consistent with normal cellular respiration. Solution for Question 33: Correct Option C. HbA1C, also known as glycated hemoglobin, is a form of hemoglobin that is used as a marker for long-term glucose control in individuals with diabetes. Measuring HbA1C levels provides valuable information about average blood glucose levels over a period of approximately 2-3 months. Ion exchange chromatography is considered the best method to measure HbA1C. In this technique, a sample containing hemoglobin, including HbA1C, is passed through a column containing an ion exchange resin. The resin has charged groups that attract and bind certain types of molecules based on their charge properties. In the case of HbA1C, it has a net negative charge due to glycation, which enables its separation from other forms of hemoglobin. By using ion exchange chromatography, HbA1C can be isolated and quantified accurately, providing a reliable measurement of glycated hemoglobin levels. This method has been widely adopted in clinical laboratories for HbA1C testing. Incorrect Options: Option A. Isoelectric focusing: Isoelectric focusing is a technique used to separate molecules based on their isoelectric points (pI). It is commonly used in protein analysis. However, it is not the preferred met hod for measuring HbA1C levels. Option B. Affinity chromatography: Affinity chromatography is a technique that utilizes specific interactions between a target molecule and a ligand immobilized on a so lid support. While it can be used for certain protein separations, it is not commonly used for measuring HbA1C levels. Option D. Electrophoresis: Electrophoresis is a general technique that involves the movement of charg ed particles in an electric field to separate molecules based on their size, charge, or other properties. A lthough electrophoresis can be used to separate different forms of hemoglobin, it is not the method of c hoice for measuring HbA1C levels, as it may not provide the same level of accuracy and precision as i on exchange chromatography. Solution for Question 34: Correct Option C: A, and E only: This option includes pyruvate carboxylase and glucose 6 phosphatase, which are indeed involved in gluconeogenesis. Pyruvate carboxylase is involved in gluconeogenesis. It catalyzes the conversion of pyruvate to oxaloacetate, which is an important intermediate in the gluconeogenic pathway. Glucose 6 phosphatase is also involved in gluconeogenesis. It catalyzes the final step of gluconeogenesis, which is the hydrolysis of glucose 6-phosphate to glucose. Pyruvate carboxylase is involved in gluconeogenesis. It catalyzes the conversion of pyruvate to oxaloacetate, which is an important intermediate in the gluconeogenic pathway. Page 31 169 Glucose 6 phosphatase is also involved in gluconeogenesis. It catalyzes the final step of gluconeogenesis, which is the hydrolysis of glucose 6-phosphate to glucose. Pyruvate carboxylase is involved in gluconeogenesis. It catalyzes the conversion of pyruvate to oxaloacetate, which is an important intermediate in the gluconeogenic pathway. Glucose 6 phosphatase is also involved in gluconeogenesis. It catalyzes the final step of gluconeogenesis, which is the hydrolysis of glucose 6-phosphate to glucose. Option A: A, B, and E only: This option includes pyruvate carboxylase, phosphoenol pyruvate kinase, and Glucose 6 phosph atase. However, this is incorrect because phosphoenol pyruvate kinase is not involved in gluconeogen esis. Option B: B and C only: This option includes phosphoenol pyruvate kinase and hexokinase. However, t his is incorrect because both enzymes are not involved in gluconeogenesis. Phosphoenol pyruvate kin ase is an enzyme involved in glycolysis, and hexokinase is responsible for the phosphorylation of gluco se during glycolysis. Option D: A, B, and C only: This option includes pyruvate carboxylase, phosphoenol pyruvate kinase, a nd hexokinase. However, this is incorrect because phosphoenol pyruvate kinase and hexokinase are n ot involved in gluconeogenesis. Both enzymes are part of the glycolysis pathway and catalyze reaction s in the opposite direction of gluconeogenesis. Solution for Question 35: Correct Answer B. The given image is of a Bilateral Oil drop cataract seen in galactosemia patients. Incorrect Options: Option A. Snowflake cataract is typically inherited as an autosomal dominant trait, meaning that it can be passed down from one affected parent to their offspring. However, in some cases, it can also occur sporadically without a family history. Option C. Her’s disease: The given image is not of her’s disease Option D. Von Gierke's disease, also known as glycogen storage disease type I (GSD I), is an inherited metabolic disorder that affects the body's ability to break down and use glycogen, a stored form of glucose (sugar). The disease is caused by a deficiency in the enzyme glucose-6-phosph atase, which is responsible for the final step in glycogen breakdown. This deficiency leads to impaired glucose release from glycogen in the liver, resulting in the accumulation of glycogen in liver

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