Biochemistry Finals Practice Questions PDF

BIOCHEMISTRY -FINALS PRACTICE QUESTIONS WITH ANSWERS TOPIC: INTRODUCTION TO BIOCHEMISTRY SET 1. 1. Which of the following best describes biochemistry? a) The study of chemical processes in rocks...

BIOCHEMISTRY -FINALS PRACTICE QUESTIONS WITH ANSWERS TOPIC: INTRODUCTION TO BIOCHEMISTRY SET 1. 1. Which of the following best describes biochemistry? a) The study of chemical processes in rocks b) The study of the structure and function of biomolecules c) The study of chemical elements in the air d) The study of chemical reactions in non-living systems Answer: b) 2. What are the main classes of bioorganic substances? a) Carbohydrates, lipids, proteins, nucleic acids b) Water and inorganic salts c) Enzymes and hormones d) Vitamins and minerals Answer: a) 3. Which of the following is NOT a function of lipids? a) Forming cell membranes b) Catalyzing biochemical reactions c) Serving as an energy source d) Acting as chemical messengers Answer: b) 4. What is the primary function of enzymes in biochemical reactions? a) To store genetic information https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 1 of 77 :  b) To catalyze and accelerate chemical reactions c) To serve as structural components d) To provide energy for cells Answer: b) 5. Which molecule is considered the powerhouse of the cell? a) Nucleus b) Ribosome c) Mitochondria d) Chloroplast Answer: c) 6. In which organelle does protein synthesis primarily occur? a) Nucleus b) Mitochondria c) Ribosome d) Lysosome Answer: c) 7. What is the role of nucleic acids in the cell? a) Providing energy b) Storing genetic information and directing protein synthesis c) Structuring cell walls d) Catalyzing enzymatic reactions Answer: b) 8. What is the primary purpose of the cell membrane? a) To synthesize proteins b) To separate the internal environment from the external environment c) To generate energy d) To transport DNA Answer: b) 9. Which of the following best defines metabolism? a) The process of cell division b) The synthesis of nucleic acids c) The set of life-sustaining chemical reactions in organisms d) The formation of organelles Answer: c) https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 2 of 77 :  10. Which organelle is involved in packaging and distributing proteins? a) Ribosome b) Nucleus c) Golgi apparatus d) Lysosome Answer: c) 11. Which type of biomolecule is primarily responsible for catalyzing chemical reactions in cells? a) Proteins b) Lipids c) Carbohydrates d) Nucleic acids Answer: a) 12. Where does photosynthesis occur in plant cells? a) Mitochondria b) Ribosomes c) Chloroplasts d) Lysosomes Answer: c) 13. What is the function of lysosomes? a) To produce ATP b) To digest unwanted materials in the cell c) To synthesize lipids d) To store genetic material Answer: b) 14. What is the main function of the endoplasmic reticulum? a) Protein and lipid synthesis b) Energy production c) Digestion of macromolecules d) Transport of genetic material Answer: a) 15. What does the nucleus of a cell contain? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 3 of 77 :  a) Lipids and proteins b) Enzymes and ribosomes c) Genetic material (DNA) d) Carbohydrates and RNA Answer: c) 16. Which of the following describes the structure of the cell membrane? a) A rigid carbohydrate layer b) A bilayer of phospholipids c) A protein-only membrane d) A single layer of nucleic acids Answer: b) 17. What is the function of peroxisomes in the cell? a) Energy production b) Protein synthesis c) Breakdown of hydrogen peroxide d) Genetic information storage Answer: c) 18. Which element is NOT one of the most common in living organisms? a) Carbon b) Oxygen c) Nitrogen d) Calcium Answer: d) 19. What happens in oxidation-reduction reactions in metabolism? a) Energy is stored in ATP b) Electrons are transferred between molecules c) Water is broken down into hydrogen and oxygen d) Proteins are synthesized from amino acids Answer: b) 20. Which cellular organelle is known as the "information center"? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 4 of 77 :  a) Endoplasmic reticulum b) Nucleus c) Golgi apparatus d) Lysosome Answer: b) SET 2. 1. Which of the following molecules is most abundant in living cells? a) Lipids b) Carbohydrates c) Proteins d) Water Answer: d) 2. Which type of bond connects the nucleotides in a DNA strand? a) Hydrogen bonds b) Peptide bonds c) Glycosidic bonds d) Phosphodiester bonds Answer: d) 3. What is the primary role of carbohydrates in cells? a) To store genetic information b) To provide energy c) To catalyze reactions d) To synthesize proteins Answer: b) 4. Which of the following macromolecules acts as the main structural component of cell membranes? a) Proteins b) Carbohydrates c) Lipids d) Nucleic acids Answer: c) https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 5 of 77 :  5. What is the primary storage form of glucose in animals? a) Starch b) Glycogen c) Cellulose d) Sucrose Answer: b) 6. Which of the following is NOT a property of enzymes? a) They are reusable b) They lower the activation energy of a reaction c) They are consumed during the reaction d) They are specific to their substrates Answer: c) 7. What type of molecule is ATP? a) Carbohydrate b) Lipid c) Nucleotide d) Protein Answer: c) 8. Which process involves the breakdown of glucose to produce energy? a) Photosynthesis b) Glycolysis c) Protein synthesis d) DNA replication Answer: b) 9. In which cellular organelle does oxidative phosphorylation occur? a) Nucleus b) Ribosome c) Mitochondria d) Chloroplast Answer: c) 10. Which of the following best describes an amino acid? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 6 of 77 :  a) A component of DNA b) A building block of proteins c) A storage form of glucose d) A type of lipid Answer: b) 11. What is the role of RNA in protein synthesis? a) To store genetic information b) To transport amino acids to ribosomes c) To catalyze biochemical reactions d) To provide energy Answer: b) 12. Which of the following structures is found in plant cells but not in animal cells? a) Cell membrane b) Nucleus c) Mitochondria d) Cell wall Answer: d) 13. Which part of the enzyme binds to the substrate? a) Active site b) Inhibitor c) Coenzyme d) Allosteric site Answer: a) 14. What is the main function of chloroplasts? a) ATP production b) Protein synthesis c) Photosynthesis d) DNA replication Answer: c) 15. Which molecule carries the genetic code from the nucleus to the ribosome for protein synthesis? a) DNA b) mRNA https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 7 of 77 :  c) tRNA d) rRNA Answer: b) 16. What is the backbone of a protein molecule composed of? a) Sugar-phosphate b) Amino acids c) Fatty acids d) Nucleotides Answer: b) 17. Which of the following molecules is primarily involved in long-term energy storage in animals? a) Glucose b) Fatty acids c) Amino acids d) Ribose Answer: b) 18. What is the function of the Golgi apparatus in the cell? a) Synthesizing proteins b) Modifying and packaging proteins c) Producing ATP d) Storing genetic information Answer: b) 19. Which of the following is NOT a function of nucleic acids? a) Storing genetic information b) Providing cellular energy c) Directing protein synthesis d) Transmitting genetic information Answer: b) 20. What is the role of cholesterol in cell membranes? a) To catalyze reactions b) To maintain membrane fluidity c) To transport molecules across the membrane d) To store energy https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 8 of 77 :  Answer: b) TOPIC: CARBOHYDRATES 1. What are carbohydrates chemically classified as? a) Hydrocarbons b) Polyhydroxyaldehydes or polyhydroxyketones c) Amino acids d) Proteins Answer: b) 2. Which of the following is NOT a function of carbohydrates? a) Providing energy b) Structural components of DNA and RNA c) Storing genetic information d) Forming part of cell membranes Answer: c) 3. What is the empirical formula of carbohydrates? a) CnH2nOn b) CnHnOn c) CnH2n+1On d) CnH2n-2On Answer: a) 4. Which of the following is the simplest form of carbohydrates? a) Disaccharides b) Polysaccharides c) Monosaccharides d) Oligosaccharides Answer: c) 5. Glucose is classified as a(n): a) Ketose b) Aldohexose c) Pentose https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 9 of 77 :  d) Disaccharide Answer: b) 6. Which disaccharide is found in milk? a) Maltose b) Sucrose c) Lactose d) Fructose Answer: c) 7. What is the linkage type found in cellulose? a) α-1,4-glycosidic b) β-1,4-glycosidic c) α-1,6-glycosidic d) β-1,6-glycosidic Answer: b) 8. Which of the following is the sweetest sugar? a) Glucose b) Galactose c) Fructose d) Sucrose Answer: c) 9. What is the function of glycogen in animals? a) Immediate energy source b) Long-term energy storage c) Structural component d) Genetic material Answer: b) 10. The primary structural polysaccharide in plants is: a) Glycogen b) Starch c) Cellulose d) Chitin Answer: c) 11. Which sugar is a component of RNA? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 10 of 77 :  a) Glucose b) Ribose c) Fructose d) Galactose Answer: b) 12. Which molecule is known as blood sugar? a) Sucrose b) Glucose c) Fructose d) Galactose Answer: b) 13. Which reaction forms a glycosidic bond between two monosaccharides? a) Hydrolysis b) Oxidation c) Condensation d) Phosphorylation Answer: c) 14. What is the reducing disaccharide found in beer and germinating grains? a) Lactose b) Sucrose c) Maltose d) Cellobiose Answer: c) 15. Which of the following is NOT a reducing sugar? a) Maltose b) Lactose c) Sucrose d) Glucose Answer: c) 16. What polysaccharide gives a blue color when treated with iodine? a) Glycogen https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 11 of 77 :  b) Starch (amylose) c) Cellulose d) Chitin Answer: b) 17. In what form is glucose stored in the liver and muscle of animals? a) Amylopectin b) Glycogen c) Starch d) Cellulose Answer: b) 18. What type of glycosidic bond is found in sucrose? a) α-1,4-glycosidic b) β-1,4-glycosidic c) α-1,2-glycosidic d) β-1,6-glycosidic Answer: c) 19. Which of the following is a homopolysaccharide? a) Hyaluronic acid b) Starch c) Heparin d) Chondroitin sulfate Answer: b) 20. What is the repeating unit in cellulose? a) D-glucose b) D-fructose c) D-galactose d) Ribose Answer: a) 21. Which of the following is NOT true about amylopectin? a) It is a branched polysaccharide b) It has α-1,4-glycosidic bonds c) It contains β-1,4-glycosidic bonds d) It has α-1,6-glycosidic bonds https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 12 of 77 :  Answer: c) 22. What enzyme is responsible for the digestion of starch in humans? a) Lactase b) Amylase c) Maltase d) Sucrase Answer: b) 23. Which polysaccharide is found in the exoskeleton of arthropods? a) Starch b) Chitin c) Glycogen d) Cellulose Answer: b) 24. What is the name of the sugar derivative that results from the reduction of glucose? a) Glucitol (Sorbitol) b) Gluconic acid c) Glucose-6-phosphate d) Glucuronate Answer: a) 25. Which polysaccharide serves as a lubricant in joints? a) Cellulose b) Hyaluronic acid c) Chitin d) Amylopectin Answer: b) 26. In the structure of D-glucose, what is the name of the anomer where the OH group on the anomeric carbon is below the plane of the ring? a) β-D-glucose b) α-D-glucose https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 13 of 77 :  c) L-glucose d) β-D-fructose Answer: b) 27. Which of the following is a trisaccharide? a) Raffinose b) Sucrose c) Lactose d) Maltose Answer: a) 28. Which polysaccharide contains a mixture of α-1,3 and β-1,4-glycosidic linkages? a) Starch b) Amylose c) Carageenan d) Glycogen Answer: c) 29. Which sugar is involved in cell recognition processes? a) Fructose b) Glucose c) Galactose d) Mannose Answer: d) 30. What is the common term for invert sugar? a) Glucose b) Maltose c) Hydrolyzed sucrose d) Amylose Answer: c) 31. Which enzyme is deficient in individuals with lactose intolerance? a) Amylase b) Sucrase c) Lactase d) Maltase https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 14 of 77 :  Answer: c) 32. Which disaccharide contains a β-1,4-glycosidic bond between glucose and galactose? a) Maltose b) Lactose c) Sucrose d) Cellobiose Answer: b) 33. Which polysaccharide can humans not digest? a) Glycogen b) Amylose c) Cellulose d) Amylopectin Answer: c) 34. Which sugar alcohol is commonly used as a sweetener in chewing gum? a) Sorbitol b) Fructose c) Galactose d) Ribose Answer: a) 35. Which polysaccharide plays a structural role in cartilage? a) Starch b) Glycogen c) Chondroitin sulfate d) Amylopectin Answer: c) 36. Which enzyme breaks down sucrose into glucose and fructose? a) Sucrase b) Lactase c) Amylase d) Maltase https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 15 of 77 :  Answer: a) 37. What is the general role of glycoproteins? a) Energy storage b) Catalyzing metabolic reactions c) Cell-cell recognition and communication d) Serving as structural components Answer: c) 38. What is the source of dietary fiber in food? a) Digestible carbohydrates b) Starch c) Indigestible carbohydrates d) Protein Answer: c) 39. What is the consequence of a lack of dietary fiber? a) Soft stools b) Increased plaque formation c) Decreased cholesterol levels d) Weight loss Answer: b) 40. What glycosaminoglycan is used as an anticoagulant? a) Hyaluronic acid b) Heparin c) Chondroitin sulfate d) Glycogen Answer: b) TOPIC: LIPIDS 1. What defines a lipid? a) A molecule that contains nitrogen b) A water-soluble organic compound c) An organic compound insoluble in water but soluble in non-polar solvents d) A compound made up of amino acids Answer: c) https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 16 of 77 :  2. Which of the following is NOT a classification of lipids based on their biochemical function? a) Energy storage lipids b) Membrane lipids c) Vitamins d) Emulsification lipids Answer: c) 3. What is the primary function of triacylglycerols? a) Membrane formation b) Energy storage c) Hormone production d) Cell signaling Answer: b) 4. Which of the following lipids is involved in membrane structure? a) Triacylglycerols b) Phospholipids c) Eicosanoids d) Steroid hormones Answer: b) 5. Which of the following is a saturated fatty acid? a) Oleic acid b) Linoleic acid c) Stearic acid d) Arachidonic acid Answer: c) 6. What does the term "polyunsaturated" mean in relation to fatty acids? a) The fatty acid has no double bonds b) The fatty acid has one double bond c) The fatty acid has two or more double bonds d) The fatty acid is fully hydrogenated Answer: c) 7. What are omega-3 fatty acids known for? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 17 of 77 :  a) Their ability to synthesize proteins b) Their role in heart health and inflammation reduction c) Their high saturation level d) Their function as enzymes Answer: b) 8. Which type of lipid is the main component of biological membranes? a) Steroid hormones b) Triacylglycerols c) Phospholipids d) Waxes Answer: c) 9. What is the key structural feature of a phospholipid? a) One fatty acid attached to glycerol b) Two fatty acids and a phosphate group attached to glycerol c) A single long-chain alcohol and a fatty acid d) Four fused carbon rings Answer: b) 10. Which lipid is classified as a steroid? a) Cholesterol b) Stearic acid c) Lecithin d) Triglyceride Answer: a) 11. What is the function of bile acids in lipid digestion? a) Breaking down proteins into amino acids b) Emulsifying dietary fats c) Synthesizing fatty acids d) Storing energy in adipocytes Answer: b) 12. Which of the following is an essential fatty acid? a) Palmitic acid b) Linoleic acid c) Stearic acid https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 18 of 77 :  d) Oleic acid Answer: b) 13. What is the primary role of cholesterol in cell membranes? a) Catalyzing biochemical reactions b) Providing energy c) Stabilizing membrane fluidity d) Serving as a precursor for vitamins Answer: c) 14. Which molecule is known as a "bad cholesterol" because of its association with cardiovascular disease? a) LDL (Low-Density Lipoprotein) b) HDL (High-Density Lipoprotein) c) VLDL (Very-Low-Density Lipoprotein) d) Chylomicrons Answer: a) 15. What are eicosanoids derived from? a) Triacylglycerols b) Cholesterol c) Arachidonic acid d) Phospholipids Answer: c) 16. Which of the following is NOT a function of eicosanoids? a) Regulating blood pressure b) Inducing labor c) Producing ATP d) Mediating inflammatory responses Answer: c) 17. What is a major function of steroid hormones? a) Energy storage b) Regulating reproduction and secondary sex characteristics c) Forming cell walls d) Enzyme activity regulation Answer: b) https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 19 of 77 :  18. Which type of fat is considered beneficial and is recommended for consumption in a balanced diet? a) Saturated fats b) Monounsaturated fats c) Trans fats d) Hydrogenated fats Answer: b) 19. Which of the following is an artificial fat substitute used in foods? a) Lecithin b) Olestra c) Stearic acid d) Cholesterol Answer: b) 20. What lipid-soluble vitamin is involved in blood clotting? a) Vitamin A b) Vitamin D c) Vitamin E d) Vitamin K Answer: d) 21. Which lipid is primarily responsible for transporting cholesterol from the liver to cells? a) HDL b) LDL c) VLDL d) Chylomicrons Answer: b) 22. What lipid class does wax belong to? a) Triacylglycerols b) Steroids c) Biological waxes d) Eicosanoids Answer: c) 23. Which process converts oils into solid fats by adding https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 20 of 77 :  hydrogen? a) Hydrolysis b) Saponification c) Hydrogenation d) Esterification Answer: c) 24. What is the primary difference between fats and oils? a) Fats are unsaturated, while oils are saturated b) Fats are solid at room temperature, while oils are liquid c) Fats contain cholesterol, while oils do not d) Fats are found in plants, while oils are found in animals Answer: b) 25. What is the function of lipoproteins? a) Catalyzing lipid digestion b) Transporting lipids in the blood c) Storing lipids in adipose tissue d) Synthesizing lipids from carbohydrates Answer: b) 26. Which lipid is a precursor for all steroid hormones? a) Cholesterol b) Palmitic acid c) Lecithin d) Oleic acid Answer: a) 27. What type of lipid forms a protective coating on the leaves and fruits of plants? a) Phospholipids b) Waxes c) Triacylglycerols d) Cholesterol Answer: b) 28. Which vitamin is known as the "antioxidant vitamin" and protects lipids from oxidation? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 21 of 77 :  a) Vitamin A b) Vitamin D c) Vitamin E d) Vitamin K Answer: c) 29. What is the primary cause of lipid rancidity? a) Hydrolysis of lipids b) Oxidation of unsaturated fatty acids c) Hydrogenation of fats d) Saponification of fatty acids Answer: b) 30. Which class of lipids is involved in cellular signaling and immune responses? a) Eicosanoids b) Phospholipids c) Steroids d) Triacylglycerols Answer: a) 31. What lipid is essential for the production of vitamin D in the skin? a) Cholesterol b) Sphingomyelin c) Stearic acid d) Triacylglycerol Answer: a) 32. Which lipid is involved in the emulsification of fats during digestion? a) Phospholipids b) Cholesterol c) Bile acids d) Triacylglycerols Answer: c) 33. What lipid disorder is characterized by high levels of LDL in the blood? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 22 of 77 :  a) Hypolipidemia b) Hypercholesterolemia c) Fatty liver disease d) Lipid peroxidation Answer: b) 34. Which lipid is important for the formation of the myelin sheath in neurons? a) Sphingomyelin b) Cholesterol c) Triacylglycerol d) Lecithin Answer: a) 35. Which of the following lipids is known to promote inflammation and allergic responses? a) Thromboxanes b) Prostaglandins c) Leukotrienes d) Cholesterol Answer: c) 36. What is the product of the saponification of triacylglycerols? a) Cholesterol b) Glycerol and fatty acid salts c) Glycerophospholipids d) Sphingolipids Answer: b) 37. Which lipoprotein is known as "good cholesterol"? a) LDL b) HDL c) VLDL d) Chylomicrons Answer: b) 38. What lipid forms the backbone of triglycerides? a) Glycerol https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 23 of 77 :  b) Fatty acids c) Cholesterol d) Phospholipids Answer: a) 39. What is the major role of biological waxes in plants and animals? a) Storing energy b) Acting as emulsifiers c) Providing protection and waterproofing d) Regulating body temperature Answer: c) 40. Which type of transport requires energy to move lipids across cell membranes? a) Passive transport b) Active transport c) Facilitated transport d) Diffusion Answer: b) TOPIC: PROTEINS 1. What are proteins made up of? A) Nucleotides B) Amino acids C) Lipids D) Sugars Answer: B 2. What percentage of a cell's mass do proteins account for after water? A) 10% B) 50% C) 15% D) 5% Answer: C 3. Which element is not commonly found in proteins? A) Carbon B) Hydrogen C) Nitrogen https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 24 of 77 :  D) Silicon Answer: D 4. What type of protein contains only amino acid residues? A) Conjugated protein B) Simple protein C) Fibrous protein D) Globular protein Answer: B 5. Albumin belongs to which class of proteins? A) Structural proteins B) Transport proteins C) Simple proteins D) Conjugated proteins Answer: C 6. Which of the following is a fibrous protein? A) Hemoglobin B) Albumin C) Collagen D) Immunoglobulins Answer: C 7. What is the function of myoglobin? A) Transport oxygen in blood B) Store oxygen in muscles C) Breakdown fats D) Fight infections Answer: B 8. What kind of protein is insulin? A) Catalytic protein B) Transport protein C) Messenger protein D) Structural protein Answer: C 9. Which amino acid is essential and must be obtained from the diet? A) Glycine B) Lysine C) Alanine D) Proline Answer: B https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 25 of 77 :  10. Which protein is responsible for oxygen transport in the blood? A) Myoglobin B) Collagen C) Hemoglobin D) Albumin Answer: C 11. Which protein stores iron in the body? A) Myoglobin B) Ferritin C) Insulin D) Albumin Answer: B 12. Which of the following proteins assists in movement? A) Myosin B) Hemoglobin C) Insulin D) Casein Answer: A 13. What kind of bond links amino acids in a protein? A) Ionic bond B) Hydrogen bond C) Peptide bond D) Disulfide bond Answer: C 14. Which of the following is not a type of secondary protein structure? A) Alpha-helix B) Beta-pleated sheet C) Tertiary coil D) Random coil Answer: C 15. What type of bond holds the alpha-helix structure together? A) Covalent bonds B) Hydrogen bonds C) Ionic bonds D) Disulfide bonds Answer: B 16. Which of the following proteins contains a prosthetic group? A) Simple protein https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 26 of 77 :  B) Conjugated protein C) Fibrous protein D) Globular protein Answer: B 17. Which amino acid is achiral? A) Glycine B) Alanine C) Phenylalanine D) Serine Answer: A 18. Which structure represents the sequence of amino acids in a protein? A) Primary structure B) Secondary structure C) Tertiary structure D) Quaternary structure Answer: A 19. What percentage of collagen makes up the body’s total protein? A) 10% B) 50% C) 30% D) 5% Answer: C 20. What is the main type of bond involved in the tertiary structure of proteins? A) Peptide bonds B) Disulfide bonds C) Hydrogen bonds D) Covalent bonds Answer: B 21. Which amino acid is most commonly found in collagen? A) Glycine B) Proline C) Lysine D) Histidine Answer: B 22. The isoelectric point is the pH at which the amino acid: A) Has a net negative charge B) Has a net positive charge https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 27 of 77 :  C) Has no net charge D) Denatures Answer: C 23. Which of the following is an example of a conjugated protein? A) Collagen B) Myoglobin C) Hemoglobin D) Albumin Answer: C 24. Which amino acid is a precursor for serotonin? A) Tyrosine B) Tryptophan C) Glycine D) Cysteine Answer: B 25. Which protein structure involves multiple polypeptide chains? A) Primary structure B) Secondary structure C) Tertiary structure D) Quaternary structure Answer: D 26. What is the primary structural difference between a fibrous and a globular protein? A) Shape B) Size C) Composition D) Charge Answer: A 27. Which protein structure is most important in determining function? A) Primary structure B) Secondary structure C) Tertiary structure D) Quaternary structure Answer: C 28. In proteins, which bond is responsible for stabilizing secondary structures? A) Peptide bond B) Hydrogen bond https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 28 of 77 :  C) Ionic bond D) Disulfide bond Answer: B 29. Which amino acid forms disulfide bonds? A) Methionine B) Cysteine C) Proline D) Histidine Answer: B 30. What is the main role of lipoproteins? A) Transport lipids B) Store oxygen C) Break down proteins D) Fight infections Answer: A 31. Which protein is important in forming blood clots? A) Albumin B) Prothrombin C) Myoglobin D) Hemoglobin Answer: B 32. Which of the following amino acids is polar? A) Valine B) Serine C) Leucine D) Glycine Answer: B 33. What is the main role of structural proteins? A) Store energy B) Regulate metabolism C) Provide mechanical support D) Catalyze reactions Answer: C 34. Which amino acid is involved in protein synthesis but not used in standard proteins? A) Selenocysteine B) Proline C) Tyrosine https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 29 of 77 :  D) Histidine Answer: A 35. What kind of molecule is an enzyme? A) Lipid B) Carbohydrate C) Protein D) Nucleic acid Answer: C 36. Which protein forms the hard protective covering of nails and hair? A) Myosin B) Keratin C) Albumin D) Globulin Answer: B 37. What is the storage form of glucose in animals? A) Glucagon B) Glycogen C) Starch D) Cellulose Answer: B 38. Which type of protein transports molecules like oxygen in the blood? A) Structural protein B) Transport protein C) Regulatory protein D) Enzymatic protein Answer: B 39. What is the primary structure of a protein determined by? A) Sequence of amino acids B) 3D shape C) Number of peptide bonds D) Polarity Answer: A 40. Which amino acid contains sulfur? A) Glycine B) Cysteine C) Tyrosine D) Alanine Answer: B https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 30 of 77 :  TOPIC: ENZYMES Set 1. Multiple Choice Questions (20) 1. What are enzymes primarily composed of? a) Lipids b) Carbohydrates c) Proteins d) Nucleic acids Answer: c) Proteins Explanation: Enzymes are mostly large, globular proteins. 2. What is the role of a cofactor in enzyme activity? a) It destroys enzymes b) It is a substrate c) It is necessary for activity d) It is the enzyme product Answer: c) It is necessary for activity Explanation: Cofactors are nonprotein components necessary for enzyme function. 3. Which of the following suffixes do most enzymes have? a) -ase b) -in c) -ose d) -peptide Answer: a) -ase Explanation: Most enzymes are named with the suffix "-ase." 4. Which enzyme class catalyzes hydrolysis reactions? a) Transferases b) Hydrolyases c) Ligases d) Isomerases Answer: b) Hydrolyases Explanation: Hydrolyases catalyze reactions that add water to break bonds. 5. What model describes how the enzyme active site is complementary to the substrate shape? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 31 of 77 :  a) Induced Fit Model b) Lock-and-Key Model c) Catalytic Model d) Substrate-Affinity Model Answer: b) Lock-and-Key Model Explanation: This model states that the active site is a rigid shape that fits the substrate. 6. Which of the following is NOT a type of enzyme regulation? a) Allosteric regulation b) Feedback inhibition c) Competitive inhibition d) Passive regulation Answer: d) Passive regulation Explanation: There is no such regulation termed "passive." 7. What is the active site of an enzyme? a) The site where products are formed b) The part where the substrate binds c) The area where cofactors bind d) The location of enzyme denaturation Answer: b) The part where the substrate binds Explanation: The active site is where the substrate binds and catalysis occurs. 8. Competitive inhibitors act by: a) Altering the enzyme shape b) Binding to the active site c) Binding to the cofactor d) Increasing substrate concentration Answer: b) Binding to the active site Explanation: Competitive inhibitors compete with the substrate for the active site. 9. Which reaction type do ligases catalyze? a) Hydrolysis b) Bond formation c) Isomerization d) Electron transfer Answer: b) Bond formation Explanation: Ligases catalyze the joining of two molecules, often using ATP. https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 32 of 77 :  10. What effect does temperature have on enzyme activity? a) Always increases activity b) Optimal at ~37°C but can denature above c) Has no effect d) Decreases activity at all times Answer: b) Optimal at ~37°C but can denature above Explanation: Enzymes have an optimal temperature, after which they can denature. 11. Which class of enzymes would catalyze the following reaction: AB + C → A + BC? a) Ligases b) Isomerases c) Lyases d) Oxidoreductases Answer: c) Lyases Explanation: Lyases add or remove groups to form or break double bonds. 12. Which enzyme subclass transfers phosphate groups? a) Kinases b) Peroxidases c) Hydrolases d) Decarboxylases Answer: a) Kinases Explanation: Kinases transfer phosphate groups often from ATP. 13. What term describes enzymes that are inhibited by their own products? a) Allosteric enzymes b) Feedback inhibitors c) Competitive inhibitors d) Irreversible inhibitors Answer: b) Feedback inhibitors Explanation: Feedback inhibition occurs when the end product inhibits an earlier enzyme in the pathway. 14. Which type of enzyme acts specifically on the bond between two amino acids? a) Glycosidases b) Esterases c) Proteases https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 33 of 77 :  d) Kinases Answer: c) Proteases Explanation: Proteases break peptide bonds between amino acids. 15. Which of the following is an example of a coenzyme? a) Zn²⁺ b) NAD⁺ c) H₂O d) ATP Answer: b) NAD⁺ Explanation: NAD⁺ is an organic cofactor that assists in enzyme function. 16. Which enzyme class includes those that transfer hydrogen atoms? a) Ligases b) Oxidoreductases c) Transferases d) Lyases Answer: b) Oxidoreductases Explanation: Oxidoreductases facilitate oxidation-reduction reactions. 17. Which of the following statements about enzyme specificity is true? a) All enzymes have absolute specificity b) Enzymes can only act on one substrate c) Enzymes can have varying specificities d) All enzymes can work on any substrate Answer: c) Enzymes can have varying specificities Explanation: Enzymes can either have absolute specificity or a broader specificity depending on their type. 18. What happens to an enzyme at very high pH levels? a) It becomes more active b) It is unaffected c) It denatures d) It converts into a coenzyme Answer: c) It denatures Explanation: High pH can lead to denaturation of proteins, including enzymes. 19. Which of the following processes does NOT involve enzymes? a) DNA replication https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 34 of 77 :  b) Metabolism c) Passive diffusion d) Protein synthesis Answer: c) Passive diffusion Explanation: Passive diffusion does not require enzymes. 20. Which model allows for flexibility of the active site to better fit the substrate upon binding? a) Lock-and-Key Model b) Induced Fit Model c) Enzyme-Substrate Complex Model d) Rigid Structure Model Answer: b) Induced Fit Model Explanation: The induced fit model suggests the active site molds to fit the substrate more effectively after initial contact. Identification Questions (10) 1. Apoenzyme: The protein part of an enzyme that is inactive on its own. 2. Cofactor: A nonprotein component that is necessary for enzyme activity (e.g., metal ions like Zn²⁺). 3. Coenzyme: An organic cofactor, often a vitamin, that assists in enzyme function. 4. Active Site: The specific part of an enzyme where the substrate binds and catalysis occurs. 5. Catalytic Site: The location within an enzyme where the actual chemical reaction takes place. 6. Feedback Control: A regulatory mechanism where the end product of a pathway inhibits an enzyme in an earlier step, preventing overproduction. 7. Isoenzymes: Different forms of the same enzyme that catalyze the same reaction but are found in different tissues and may have different kinetics. 8. Allosteric Regulation: A form of regulation where molecules bind to sites other than the active site to enhance or inhibit enzyme activity. 9. Saturated Solution: A point where increasing substrate concentration no longer increases reaction rate because all active sites are occupied. 10. Competitive Inhibition: A type of inhibition where the inhibitor competes with the substrate for binding to the active site. Set 2. https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 35 of 77 :  Multiple Choice Questions General Characteristics of Enzymes 1. What are enzymes primarily composed of? a) Lipids b) Proteins c) Carbohydrates d) Nucleic acids Answer: b) Proteins 2. Which of the following is NOT true about enzymes? a) They increase the reaction rate. b) They are consumed in the reaction. c) They lower the activation energy. d) They can be reused. Answer: b) They are consumed in the reaction. 3. Enzymes that consist only of amino acid chains are classified as: a) Conjugated enzymes b) Simple enzymes c) Holoenzymes d) Apoenzymes Answer: b) Simple enzymes 4. Which term describes the non-protein part of a conjugated enzyme? a) Apoenzyme b) Cofactor c) Holoenzyme d) Catalyst Answer: b) Cofactor 5. What is the term for the specific location where the substrate binds to the enzyme? a) Active site b) Binding site c) Catalytic site d) Transition site Answer: a) Active site Classification of Enzymes 6. Which enzyme class catalyzes oxidation-reduction reactions? a) Hydrolases b) Transferases c) Oxidoreductases d) Lyases https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 36 of 77 :  Answer: c) Oxidoreductases 7. What type of enzyme transfers a functional group between molecules? a) Ligases b) Transferases c) Lyases d) Isomerases Answer: b) Transferases 8. Which enzyme class catalyzes the rearrangement of atoms within a molecule? a) Isomerases b) Lyases c) Hydrolases d) Ligases Answer: a) Isomerases 9. Which enzyme catalyzes the removal of a carboxyl group? a) Decarboxylase b) Dehydratase c) Hydratase d) Aminotransferase Answer: a) Decarboxylase 10. What type of reaction is catalyzed by ligases? a) Bond cleavage with water b) Bond formation using ATP c) Rearrangement of atoms d) Oxidation-reduction Answer: b) Bond formation using ATP Enzyme Specificity 11. Which specificity allows enzymes to act only on a single substrate? a) Stereochemical specificity b) Absolute specificity c) Group specificity d) Linkage specificity Answer: b) Absolute specificity 12. Which enzyme is specific to the stereoisomer L-amino acids? a) Trypsin b) L-amino acid oxidase c) Carboxypeptidase d) Phosphatase Answer: b) L-amino acid oxidase 13. Phosphatases are an example of enzymes with: a) Absolute specificity https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 37 of 77 :  b) Group specificity c) Linkage specificity d) Stereochemical specificity Answer: c) Linkage specificity Enzyme Kinetics 14. At a constant enzyme concentration, increasing substrate concentration will: a) Always decrease enzyme activity b) Eventually saturate the enzyme c) Have no effect on enzyme activity d) Decrease the activation energy indefinitely Answer: b) Eventually saturate the enzyme 15. What is the optimum temperature for most human enzymes? a) 25°C b) 37°C c) 50°C d) 100°C Answer: b) 37°C 16. Pepsin, an enzyme in the stomach, has an optimal pH of: a) 7.0 b) 8.0 c) 2.0 d) 5.5 Answer: c) 2.0 Mechanism of Action 17. The lock-and-key model suggests that: a) The active site is flexible and changes shape. b) The active site has a fixed shape. c) Substrates bind randomly to the enzyme. d) Enzymes work without specific binding. Answer: b) The active site has a fixed shape. 18. Which model accounts for the flexibility of the active site? a) Lock-and-key model b) Induced fit model c) Enzyme-substrate model d) Transition state model Answer: b) Induced fit model Enzyme Inhibition https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 38 of 77 :  19. A competitive inhibitor: a) Binds to a site other than the active site. b) Forms irreversible bonds with the enzyme. c) Resembles the substrate. d) Increases enzyme activity. Answer: c) Resembles the substrate. 20. Noncompetitive inhibitors: a) Compete with the substrate for the active site. b) Change the enzyme's shape. c) Have the same structure as the substrate. d) Bind irreversibly to the enzyme. Answer: b) Change the enzyme's shape. Factors Affecting Enzyme Activity 21. Increasing enzyme concentration while keeping substrate concentration constant will: a) Decrease enzyme activity b) Have no effect on enzyme activity c) Increase enzyme activity d) Decrease reaction rate Answer: c) Increase enzyme activity 22. At which point does the enzyme reach maximum activity due to substrate saturation? a) Turnover number b) Enzyme saturation c) Activation energy d) Optimum pH Answer: b) Enzyme saturation 23. Which factor can denature an enzyme by disrupting hydrogen bonds and ionic bonds? a) Temperature b) pH c) Substrate concentration d) Enzyme concentration Answer: a) Temperature 24. If an enzyme's optimum pH is 7.0, what happens at pH 2.0? a) Enzyme activity increases b) Enzyme activity decreases c) Enzyme activity remains constant d) Enzyme becomes more stable Answer: b) Enzyme activity decreases 25. Enzymes exhibit maximum activity at a specific temperature and pH. This https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 39 of 77 :  condition is known as: a) Turnover state b) Optimum state c) Transition state d) Enzyme saturation Answer: b) Optimum state Extremozymes 26. Which extremophile thrives in highly acidic conditions? a) Halophile b) Acidophile c) Cryophile d) Piezophile Answer: b) Acidophile 27. Extremozymes are particularly valuable in industrial applications because: a) They operate in extreme conditions b) They are more stable than other enzymes c) They can be used in cold wash cycles d) All of the above Answer: d) All of the above 28. An extremophile that grows in temperatures below 15°C is called a: a) Thermophile b) Halophile c) Cryophile d) Alkaliphile Answer: c) Cryophile 29. Which extremophile would you find thriving in environments with high salinity? a) Hydrothermophile b) Alkaliphile c) Halophile d) Acidophile Answer: c) Halophile 30. What is an extremophile enzyme that can resist extreme pH, temperature, and pressure called? a) Cofactor b) Extremolyte c) Extremozyme d) Isozyme Answer: c) Extremozyme Enzyme Regulation https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 40 of 77 :  31. Which type of enzyme regulation involves feedback inhibition? a) Allosteric regulation b) Proenzyme activation c) Feedback control d) Isoenzymes Answer: c) Feedback control 32. In feedback control, the product of the reaction pathway: a) Activates allosteric enzymes b) Inhibits an earlier step in the pathway c) Speeds up the enzyme reaction d) Irreversibly binds to the enzyme Answer: b) Inhibits an earlier step in the pathway 33. Zymogens are enzymes that are: a) Inactive precursors requiring activation b) Allosterically regulated c) Active without modification d) Isoenzymes of one another Answer: a) Inactive precursors requiring activation 34. The removal of a fragment from trypsinogen to form trypsin is an example of: a) Allosteric activation b) Proenzyme activation c) Feedback inhibition d) Competitive inhibition Answer: b) Proenzyme activation 35. Allosteric enzymes are regulated by: a) The substrate binding to the active site b) The presence of cofactors only c) Molecules binding at sites other than the active site d) Changing the pH of the enzyme environment Answer: c) Molecules binding at sites other than the active site Clinical and Industrial Applications 36. Which enzyme is used as a diagnostic marker for heart attacks? a) Lactate dehydrogenase (LDH) b) Amylase c) Sucrase d) Trypsin Answer: a) Lactate dehydrogenase (LDH) 37. What enzyme is used in cold wash detergents for stain removal? a) Amylase b) Lipase https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 41 of 77 :  c) Protease d) Extremozymes Answer: d) Extremozymes 38. Elevated levels of alkaline phosphatase (ALP) in the blood may indicate: a) Heart attack b) Bone disease c) Pancreatic disease d) Hepatitis Answer: b) Bone disease 39. Which enzyme catalyzes the conversion of lactate to pyruvate? a) Pyruvate kinase b) Lactate dehydrogenase c) Creatine kinase d) Alanine aminotransferase Answer: b) Lactate dehydrogenase 40. What are isoenzymes? a) Enzymes with identical structures but different functions b) Enzymes that catalyze the same reaction but have different structures c) Inactive forms of enzymes d) Enzymes found only in extreme environments Answer: b) Enzymes that catalyze the same reaction but have different structures TOPIC: NUCLEIC ACIDS Set 1. Multiple Choice Questions (20 items) (Each question has one correct answer with an explanation.) 1. What is the repeating unit of DNA or RNA polymer? A. Ribose B. Deoxyribose C. Nucleotide D. Phosphate Answer: C. Nucleotide Explanation: Nucleotides are the monomers that form the polymers DNA and RNA. They consist of a sugar, a base, and a phosphate group. 2. Which sugar is found in RNA? A. Deoxyribose B. Fructose C. Ribose https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 42 of 77 :  D. Glucose Answer: C. Ribose Explanation: Ribose is the sugar in RNA, whereas deoxyribose is found in DNA. 3. In the DNA double helix, which base pairs with guanine (G)? A. Thymine (T) B. Adenine (A) C. Uracil (U) D. Cytosine (C) Answer: D. Cytosine (C) Explanation: Guanine pairs with cytosine through three hydrogen bonds in DNA. 4. What is the diameter of the DNA double helix? A. 1 nm B. 2 nm C. 3.4 nm D. 10 nm Answer: B. 2 nm Explanation: The DNA double helix has a diameter of 2 nm. 5. Which type of RNA carries amino acids to the ribosome? A. mRNA B. tRNA C. rRNA D. snRNA Answer: B. tRNA Explanation: tRNA (transfer RNA) transports amino acids to the ribosome for protein synthesis. 6. What is the main function of RNA polymerase during transcription? A. Unwinding the DNA B. Synthesizing ribosomes C. Assembling nucleotides into RNA D. Splicing RNA Answer: C. Assembling nucleotides into RNA Explanation: RNA polymerase builds the RNA strand by assembling ribonucleotides complementary to the DNA template strand. 7. What type of bonds hold base pairs together in DNA? A. Ionic bonds B. Covalent bonds C. Hydrogen bonds D. Peptide bonds Answer: C. Hydrogen bonds Explanation: Hydrogen bonds connect complementary base pairs (A-T and G-C) in the DNA double helix. 8. Which base is unique to RNA? https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 43 of 77 :  A. Thymine B. Uracil C. Cytosine D. Guanine Answer: B. Uracil Explanation: Uracil is present in RNA instead of thymine, which is found in DNA. 9. What is the role of helicase in DNA replication? A. Joining Okazaki fragments B. Synthesizing primers C. Unwinding the DNA double helix D. Pairing bases Answer: C. Unwinding the DNA double helix Explanation: Helicase unwinds the DNA to prepare it for replication. 10. Which process copies DNA into an identical strand? A. Transcription B. Translation C. Replication D. Transformation Answer: C. Replication Explanation: DNA replication produces two identical copies of the original DNA molecule. 11. What type of mutation involves substituting one nucleotide for another? A. Point mutation B. Deletion C. Insertion D. Frameshift mutation Answer: A. Point mutation Explanation: A point mutation changes a single nucleotide in the DNA sequence. 12. What forms the backbone of DNA? A. Base pairs B. Sugar-phosphate groups C. Hydrogen bonds D. Amino acids Answer: B. Sugar-phosphate groups Explanation: The sugar-phosphate backbone supports the structure of DNA and RNA. 13. What is the sequence written from the 5′ to 3′ end called? A. Genetic code B. DNA helix C. Nucleic acid sequence D. Codon https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 44 of 77 :  Answer: C. Nucleic acid sequence Explanation: Nucleic acid sequences are described starting from the 5′ end and listing the bases in order. 14. What does the "A" in mRNA stand for? A. Acceptor B. Adenine C. Acid D. Amino Answer: D. Amino Explanation: mRNA stands for messenger RNA, which carries the message for amino acid assembly. 15. What type of repair removes and replaces up to 24-32 nucleotides? A. BER B. NER C. Recombinant repair D. Ligase repair Answer: B. NER Explanation: Nucleotide excision repair (NER) is a mechanism to remove larger DNA lesions. 16. What shape does tRNA take in its three-dimensional structure? A. Double helix B. Cloverleaf C. Straight chain D. L-shaped Answer: D. L-shaped Explanation: tRNA has a cloverleaf secondary structure but folds into an L-shape in 3D. 17. What does the term "degenerate" mean in the genetic code? A. Nonfunctional codons exist B. A single codon codes for multiple amino acids C. Multiple codons can code for the same amino acid D. Some bases overlap between codons Answer: C. Multiple codons can code for the same amino acid Explanation: Degeneracy means redundancy in the genetic code. 18. Which enzyme joins Okazaki fragments? A. Helicase B. Ligase C. Polymerase D. Topoisomerase Answer: B. Ligase Explanation: DNA ligase seals nicks between Okazaki fragments to complete DNA replication. 19. Which codons signal the termination of protein synthesis? A. AUG https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 45 of 77 :  B. UAA, UAG, UGA C. GGG, CCC, AAA D. UUU, UGC, UAC Answer: B. UAA, UAG, UGA Explanation: These are stop codons that terminate translation. 20. What happens during transcription? A. DNA is copied into mRNA. B. mRNA is translated into proteins. C. DNA is replicated. D. tRNA transports amino acids. Answer: A. DNA is copied into mRNA. Explanation: Transcription converts DNA into messenger RNA. Identification (10 items) 1. The sugar found in RNA. Answer: Ribose 2. The enzyme that synthesizes RNA during transcription. Answer: RNA polymerase 3. The complementary base of adenine in DNA. Answer: Thymine 4. The process by which DNA is copied into an identical strand. Answer: Replication 5. A mutation where nucleotides are added to the DNA sequence. Answer: Insertion 6. The RNA molecule that directs the sequence of amino acids in a protein. Answer: mRNA 7. The type of bond between the sugar and phosphate in DNA. Answer: Phosphodiester bond 8. The purine bases found in nucleic acids. Answer: Adenine and guanine 9. The enzyme responsible for sealing nicks in the DNA backbone. Answer: DNA ligase 10. The repeating sequence that makes up the backbone of DNA and RNA. Answer: Sugar-phosphate Set 2. Multiple Choice Questions Structure of Nucleic Acids https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 46 of 77 :  1. What are the three main components of a nucleotide? a) Nitrogenous base, lipid, phosphate b) Ribose, phosphate, nitrogenous base c) Nitrogenous base, sugar, phosphate d) Protein, sugar, phosphate Answer: c) Nitrogenous base, sugar, phosphate 2. Which sugar is found in DNA? a) Ribose b) Glucose c) Deoxyribose d) Fructose Answer: c) Deoxyribose 3. What nitrogenous base is unique to RNA? a) Thymine b) Adenine c) Guanine d) Uracil Answer: d) Uracil 4. How many hydrogen bonds stabilize a G-C base pair? a) One b) Two c) Three d) Four Answer: c) Three 5. What is the directionality of a DNA sequence? a) 3’ to 5’ b) 5’ to 3’ c) 1’ to 2’ d) Random Answer: b) 5’ to 3’ DNA Structure and Function 6. What shape does the DNA molecule take? a) Single helix b) Alpha helix c) Double helix d) Triple helix Answer: c) Double helix 7. Which bonds connect the sugar-phosphate backbone of DNA? a) Hydrogen bonds b) Peptide bonds c) Phosphodiester bonds https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 47 of 77 :  d) Ionic bonds Answer: c) Phosphodiester bonds 8. What creates the major and minor grooves in the DNA double helix? a) Base stacking b) The twisting of the helix c) Hydrogen bonding d) Phosphorylation Answer: b) The twisting of the helix 9. What is the function of the sugar-phosphate backbone? a) It stores genetic information. b) It protects nitrogenous bases. c) It provides structural support. d) It facilitates protein synthesis. Answer: c) It provides structural support. 10. How many base pairs are found in one complete turn of a DNA helix? a) 5 b) 10 c) 15 d) 20 Answer: b) 10 DNA Replication 11. Which enzyme unwinds the DNA double helix during replication? a) DNA polymerase b) Helicase c) Ligase d) Topoisomerase Answer: b) Helicase 12. What are Okazaki fragments? a) Continuous DNA strands b) Short DNA fragments synthesized on the lagging strand c) The RNA primers in replication d) Proteins that assist in replication Answer: b) Short DNA fragments synthesized on the lagging strand 13. What is the function of DNA polymerase? a) To unwind the DNA helix b) To synthesize primers c) To add nucleotides to the growing DNA strand d) To splice introns from RNA Answer: c) To add nucleotides to the growing DNA strand 14. DNA replication is: a) Conservative https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 48 of 77 :  b) Semi-conservative c) Dispersive d) Random Answer: b) Semi-conservative 15. Which enzyme seals nicks in the sugar-phosphate backbone? a) Helicase b) DNA polymerase c) DNA ligase d) Primase Answer: c) DNA ligase RNA Structure and Function 16. What sugar is found in RNA? a) Ribose b) Deoxyribose c) Fructose d) Maltose Answer: a) Ribose 17. Which type of RNA carries the genetic code from the nucleus to the ribosome? a) tRNA b) mRNA c) rRNA d) snRNA Answer: b) mRNA 18. What is the function of tRNA? a) Carries the genetic code to the ribosome b) Synthesizes proteins c) Brings amino acids to the ribosome d) Forms ribosomal subunits Answer: c) Brings amino acids to the ribosome 19. Which base pairs with adenine in RNA? a) Cytosine b) Guanine c) Uracil d) Thymine Answer: c) Uracil 20. What shape does tRNA have? a) Linear b) Cloverleaf c) Double helix d) Beta sheet https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 49 of 77 :  Answer: b) Cloverleaf Transcription and Translation 21. What enzyme catalyzes transcription? a) RNA polymerase b) DNA polymerase c) Ligase d) Helicase Answer: a) RNA polymerase 22. Which process converts mRNA into a protein? a) Replication b) Transcription c) Translation d) Splicing Answer: c) Translation 23. What sequence signals the start of transcription? a) Terminator b) Promoter c) Codon d) Enhancer Answer: b) Promoter 24. Which RNA sequence is complementary to a DNA strand with a sequence 5'-GCTA-3'? a) 3'-CGAU-5' b) 5'-CGAU-3' c) 3'-GCUA-5' d) 5'-GCUA-3' Answer: a) 3'-CGAU-5' 25. In which cellular organelle does translation occur? a) Nucleus b) Ribosome c) Mitochondria d) Lysosome Answer: b) Ribosome The Genetic Code 26. How many nucleotides are in a codon? a) One b) Two c) Three d) Four https://knowt.com/note/6f85fcac-8c88-49f1-ae9a-eacb43b5f9b4/BIOCHEMISTRY--FINALS 12/14/24, 3 23 AM Page 50 of 77 :  Answer: c) Three 27. The codon AUG codes for which amino acid? a) Glycine b) Methionine c) Serine d) Leucine Answer: b) Methionine 28. How many stop codons are there? a) One b) Two c) Three d) Four Answer: c) Three 29. What does the term "degenerate" mean in the context of the genetic code? a) A codon codes for multiple amino acids. b) Multiple codons code for the same amino