Practice Chem 103

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Chemistry

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Jan 9, 2024

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Chemistry 103.3 – Spring 2022 Final Exam - May 20, 2022 Name: (print)___________________________________ Part 1: Circle the best answer for each question. 2 pts each (50 points) 1. A glucogenic amino acid may feed its carbon skeleton into each intermediate pool listed below EXCEPT: A. Malate B. Succinate C. a -Ketoglutarate D. Acetyl-CoA E. Fumarate 2. Which of the following molecules carries an amino group from the tissues to the liver? A. Fructose B. Chylomicrons C. Ketone bodies D. Glutamine E. Lactate 3. Which pathway listed below operates in liver but not in muscle? A. Glycolysis B. Glycogen breakdown C. Glycogen synthesis D. Gluconeogenesis with release of free glucose E. Insulin-stimulated pathways 4. When blood glucose is abnormally low, the pancreas releases: A. Epinephrine B. Insulin C. Thyroxin D. Glucagon E. Cholesterol 5. Which statement below about fatty acid degradation is false ? A. It involves cycles of cleaving a 2-carbon fragment from the carboxyl end (the b -carbon). B. It takes place in the mitochondrial matrix. C. ATP is required to convert each FA to a CoA derivative. D. Each cycle requires 2 NAD+ molecules. E. Each fatty acid is initially converted to a carnitine derivative. 1

6. Which statement about the Citric Acid Cycle is false ? A. One 6C molecule is converted to a 4C molecule B. Oxidative decarboxylation occurs twice C. The cycle is activated by an increase in [AMP] D. Ketogenic amino acids feed into the a -ketoglutarate pool. E. High levels of ATP suppresses the activity of the Cycle 7. Fructose-2,6-bisphosphate is A. An activator of PFK-1 B. Depleted by the downstream effects of glucagon C. An activator of glycogen breakdown D. An inhibitor of the Citric Acid Cycle E. An intermediate of the glycolytic pathway 8. The structure of urea is H 2 N-C(=O)-NH 2. Which statement below about the Urea Cycle is FALSE ? A. It occurs entirely in the mitochondrial matrix. B. Arginine can be synthesized by this pathway. C. Fumarate is a product of the pathway. D. NH 4 + donates one of the amino groups of urea. E. Aspartate donates one of the amino groups of urea. 9. The first 5 reactions of glycolysis are referred to as the "energy investment" portion of the process because these steps A. consume ATP instead of producing it B. generate waste products which cost ATP for disposal C. produce NADH which is less energy-rich than ATP D. involve several endergonic isomerizations E. none of the above 10. In contrast to transamination, deamination of an amino acid results in A. a new amino acid B. free NH 4 + C. glutamine D. transfer of amino group to another molecule 11. One of the enzymes involved in glycolysis is phosphofructokinase. What type of biochemical reaction does it catalyze? A. Transfer of a carbonyl group from glucose to fructose. B. Removal of a phosphate group from fructose-6-phosphate. C. Transfer of a phosphate group from ATP to fructose-6-phosphate. D. Transfer of a phosphate group from fructose-1,6-bisphosphate to fructose. E. None of the above 2

12. One round of fatty acid synthesis results in A. consumption of 2 NADH/H+ B. consumption of 2 FADH 2 C. release of 1 NADH/H+ and 1 ATP D. consumption of 2 NADPH/H+ E. release of 2 NADPH/H+ 13. The major site of formation of acetoacetate from fatty acids is the: A. adipose tissue B. intestinal mucosa C. muscle D. liver E. kidney 14. Which intermediate of the Citric Acid Cycle can be increased by direct transamination of ASP? A. fumarate B. isocitrate C. succinate D. oxaloacetate E. citrate 15. Of the glycolytic enzymes given below, which one can be regulated by phosphorylation by PKA? A. aldolase B. glyceraldehyde-3-P dehydrogenase C. pyruvate kinase D. phosphoglycerate kinase E. hexokinase 16. Which statement about Acetyl-CoA carboxylase is false ? A. it is the key regulatory step of the fatty acid synthesis pathway B. it is activated by phosphorylation by PKA C. it can be found in the cytoplasm D. the reaction requires CO 2 E. it is activated by insulin action 17. NADH produced by glycolysis under anaerobic conditions will be re-oxidized in the cytosol by which of the following enzymes so that glycolysis continues? A. succinate dehydrogenase B. glyceraldehyde-3-P dehydrogenase C. lactate dehydrogenase D. a -ketoglutarate dehydrogenase E. substrate-level phosphorylation 3

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