NBCE Biochemistry Questions

NBCE Biochemistry Questions Which pair of enzymes listed below is unique to gluconeogensis? A. Pyruvate kinase and pyruvate carboxylase B. Phosphoenolpyruvate carboxykinase and pyruvate carboxylase C. Fructose bispho ...

NBCE Biochemistry Questions Which pair of enzymes listed below is unique to gluconeogensis? A. Pyruvate kinase and pyruvate carboxylase B. Phosphoenolpyruvate carboxykinase and pyruvate carboxylase C. Fructose bisphosphatase and phosphofructokinase D. Pyruvate dehydrogenase and glucose 6-phosphatase - ANS - B. Phosphoenolpyruvate carboxykinase and pyruvate carboxylase Which 2 polysaccharides contain the same types of bonds? A. Cellulose and amylose B. Amylopectin and glycogen C. Glycogen and cellulose D. Amylose and amylopectin - ANS - B. Amylopectin and glycogen Which glycolytic enzyme catalyzes a substrate-level phosphorylation? A. Glucokinase B. Phosphofructokinase C. Phosphoglycerate kinase D. Hexokinase - ANS - C. Phosphoglycerate kinase An example of a food that is an excellent source of soluble fiber is: A. Wheat bran cereal B. Brown rice C. Whole wheat bread D. Oatmeal - ANS - D. Oatmeal Which polysaccharide has the highest proportion of alpha-1,4 glycosidic linkages? A. Starch B. Amylopectin C. Glycogen D. Amylose - ANS - D. Amylose Which sugar has a C-2 carbonyl carbon? A. Fructose B. Galactose C. Glucose D. Mannose - ANS - A. Fructose Which molecule is not essential for the complete degradation of glycogen in muscle and liver? A. Inorganic phosphate B. Glycogen phosphorylase C. Glycogenin D. Glycogen debranching enzyme - ANS - C. Glycogenin Which glucose transporter is saturated or close to saturation only after a carbohydrate-rich meal? A. GLUT-1 B. GLUT-2 C. GLUT-3 D. GLUT-4 - ANS - D. GLUT-4 Which of the following is NOT considered a reducing sugar? A. Glucose B. Fructose C. Sucrose D. Lactose - ANS - C. Sucrose What are carbohydrates that consist of long disaccharide repeats and are important components of connective tissue called? A. Peptidoglycan B. Proteoglycans C. Glycogen D. Glycosaminoglycans - ANS - D. Glycosaminoglycans Conversion of glucose into carbon dioxide and passage of its electrons to molecular oxygen represents the complete ______ of the sugar. A. Oxidation B. Reduction C. Phosphorylation D. Destruction - ANS - A. Oxidation The action of what enzyme during glycolysis directly produces one molecule of NADH per molecule of substrate? A. Hexokinase D B. Phosphofructokinase-1 C. Glyceraldehyde-3-phosphate dehydrogenase D. a-ketoglutarate dehydrogenase - ANS - C. Glyceraldehyde-3-phosphate dehydrogenase An abundance of what substrate will inhibit some of the enzymes of the citric acid cycle? A. Adenosine diphosphate B. Acetyl-coenzyme A C. NADH D. Glucose - ANS - C. NADH What is the major source of energy fuel in the average human diet? A. Carbohydrates B. Ethanol C. Fats D. Proteins - ANS - A. Carbohydrates Starch is the most common digestible polysaccharide in plants and exists mainly as amylose and amylopectin. These polymers are composed of which basic residue? A. D-fructose B. D-galactose C. D-glucose D. D-ribose - ANS - C. D-glucose Which of the following forms of dietary fiber is insoluble? A. Cellulose B. Gum C. Mucilages D. Pectin - ANS - A. Cellulose The hydrolysis of lactose by lactase produces equimolar amounts of which 2 monosaccharides? A. Fructose and glucose B. Fructose and galactose C. Galactose and glucose D. Glucose and glucose - ANS - C. Galactose and glucose Which of the following describes glycogenin? A. it is a protein of muscular glycogen B. it has no enzymatic activity C. it is attached to the non reductive end of glycogen D. It has an amylo-(1,4-1,6)-transglycosylase activity - ANS - A. it is a protein of muscular glycogen Which of the following describes glycogen? A. It is a heteropolysaccharide B. it is a polymer of (a1-4)-linked subunits of glucose, with (a1-6) branches every 24 to 30 residues C. it has many more monosaccharide units than starch D. It is a form of stored energy in cytoplasmic vesicles - ANS - C. it has many more monosaccharide units than starch Which is true of UDP-glucose A. it is a substrate of UDP-glucose pyrophosphorylase B. it contains one sugar with five carbons and one sugar with six carbons C. it is a substrate of the degradation of glycogen D. It is an allosteric activator of glycogen-branching enzyme - ANS - B. it contains one sugar with five carbons and one sugar with six carbons Which is true of glycogen phosphorylase? A. it is active in its b form (phosphorylase b) B. it is phosphorylated by phosphoprotein phosphatase C. when not phosphorylated, it is activated in the presence of glucose 6-phosphate in the liver D. when phosphorylated, it is inactive in the presence of glucose - ANS - D. when phosphorylated, it is inactive in the presence of glucose Which of the following enzymes represents the step where the second high-energy phosphate is invested in glycolysis? A. pyruvate kinase B. 3-phosphoglycerate dehydrogenase C. phosphofructokinase