Practice Quiz - Biochemistry PDF

1. **What does DNA stand for?** A) Deoxyribonucleic Acid B) Ribonucleic Acid C) Dextrorotatory Acid D) Ribosomal DNA **Answer: Deoxyribonucleic Acid** 2. **What is the primary function of RNA?** A) Stores genetic information B) Transmits signals C) Helps build proteins D) Repairs...

1. **What does DNA stand for?** A) Deoxyribonucleic Acid B) Ribonucleic Acid C) Dextrorotatory Acid D) Ribosomal DNA **Answer: Deoxyribonucleic Acid** 2. **What is the primary function of RNA?** A) Stores genetic information B) Transmits signals C) Helps build proteins D) Repairs DNA **Answer: Helps build proteins** 3. **Which of the following is a difference between DNA and RNA?** A) DNA contains uracil, RNA contains thymine B) DNA is single-stranded, RNA is double-stranded C) RNA contains uracil, DNA contains thymine D) RNA is located in the nucleus, DNA is found in the cytoplasm **Answer: RNA contains uracil, DNA contains thymine** 4. **Which of the following is a type of RNA that is involved in protein synthesis?** A) mRNA B) tRNA C) rRNA D) All of the above **Answer: All of the above** 5. **What type of bond holds the two strands of DNA together in its double-helix structure?** A) Covalent bonds B) Hydrogen bonds C) Ionic bonds D) Peptide bonds **Answer: Hydrogen bonds** 6. **Which enzyme is responsible for unwinding the DNA during replication?** A) DNA polymerase B) Ligase C) Helicase D) Primase **Answer: Helicase** 7. **In the process of transcription, what is synthesized from a DNA template?** A) Protein B) mRNA C) tRNA  D) DNA **Answer: mRNA** 8. **What is the main role of ribosomal RNA (rRNA)?** A) Carry genetic information from the DNA to the ribosome B) Catalyze protein synthesis at the ribosome C) Transfer amino acids to the ribosome D) Protect DNA from damage **Answer: Catalyze protein synthesis at the ribosome** 9. **Which of the following is a type of mutation where one base is replaced by another?** A) Frameshift mutation B) Substitution mutation C) Deletion mutation D) Insertion mutation **Answer: Substitution mutation** 10. **Which molecule acts as the "energy currency" of the cell?** A) DNA B) RNA C) ATP D) NADH **Answer: ATP** 11. **Which of the following is the simplest form of carbohydrates?** A) Monosaccharides B) Disaccharides C) Polysaccharides D) Oligosaccharides **Answer: Monosaccharides** 12. **Which monosaccharide is known as blood sugar?** A) Fructose B) Glucose C) Galactose D) Ribose **Answer: Glucose** 13. **What type of bond links monosaccharides to form disaccharides?** A) Glycosidic bond B) Hydrogen bond C) Ionic bond D) Peptide bond **Answer: Glycosidic bond** 14. **Which disaccharide is composed of glucose and fructose?** A) Maltose  B) Lactose C) Sucrose D) Trehalose **Answer: Sucrose** 15. **What is the primary function of glycogen in animals?** A) Energy storage B) Structural support C) Protein synthesis D) Enzyme activation **Answer: Energy storage** 16. **Which carbohydrate is indigestible by humans but important for digestive health?** A) Starch B) Cellulose C) Glycogen D) Lactose **Answer: Cellulose** 17. **Which enzyme is responsible for breaking down starch into maltose?** A) Amylase B) Lipase C) Protease D) Lactase **Answer: Amylase** 18. **Which of the following is a type of protein metabolism?** A) Protein synthesis B) Protein digestion C) Protein turnover D) All of the above **Answer: All of the above** 19. **What is the primary role of amino acids in the body?** A) To store energy B) To form enzymes and hormones C) To provide structural support to cells D) To form starch **Answer: To form enzymes and hormones** 20. **Which process is responsible for removing the amino group from amino acids?** A) Transamination B) Hydrolysis C) Oxidative deamination D) Glycosylation **Answer: Transamination** 21. **Which molecule is produced during oxidative deamination of glutamate?** A) Pyruvate B) Acetyl-CoA C) Ammonia D) Urea **Answer: Ammonia** 22. **Which metabolic pathway generates the most ATP per glucose molecule?** A) Glycolysis B) Citric acid cycle C) Electron transport chain D) Fermentation **Answer: Electron transport chain** 23. **Where does β-oxidation of fatty acids primarily occur?** A) Cytoplasm B) Mitochondria C) Nucleus D) Ribosome **Answer: Mitochondria** 24. **Which enzyme is required for the activation of fatty acids before they enter β-oxidation?** A) Acetyl-CoA synthetase B) Carnitine acyltransferase C) Coenzyme A D) Lipase **Answer: Acetyl-CoA synthetase** 25. **What is the final product of one round of β-oxidation of fatty acids?** A) Acetyl-CoA B) NADH C) FADH₂ D) Pyruvate **Answer: Acetyl-CoA** 26. **Which of the following is an essential amino acid?** A) Alanine B) Glutamate C) Leucine D) Glycine **Answer: Leucine** 27. **What is the primary role of NAD⁺ in metabolism?** A) To act as an energy carrier by accepting electrons B) To provide energy for protein synthesis C) To break down carbohydrates into glucose D) To transport fatty acids into the mitochondria  **Answer: To act as an energy carrier by accepting electrons** 28. **Which of the following is true about the citric acid cycle?** A) It occurs in the cytoplasm B) It produces glucose from pyruvate C) It generates ATP, NADH, and FADH₂ D) It is also known as glycolysis **Answer: It generates ATP, NADH, and FADH₂** 29. **Which type of fatty acid is metabolized through β-oxidation?** A) Saturated fatty acids B) Unsaturated fatty acids C) Both saturated and unsaturated fatty acids D) Both fatty acids and carbohydrates **Answer: Both saturated and unsaturated fatty acids** 30. **Which molecule is produced in the last step of the citric acid cycle?** A) Acetyl-CoA B) Oxaloacetate C) Malate D) CO₂ **Answer: Oxaloacetate** 31. **What is the primary function of lipoproteins?** A) To store glucose B) To transport lipids in the bloodstream C) To break down fats D) To synthesize fatty acids **Answer: To transport lipids in the bloodstream** 32. **Which lipoprotein is often referred to as "bad cholesterol"?** A) HDL B) LDL C) VLDL D) Chylomicrons **Answer: LDL** 33. **Which molecule is a precursor for fatty acid synthesis?** A) Acetyl-CoA B) NADH C) Glucose D) Pyruvate **Answer: Acetyl-CoA** 34. **What is the primary energy source for cells during prolonged fasting?** A) Glucose B) Fatty acids C) Amino acids  D) Glycogen **Answer: Fatty acids** 35. **What is the first molecule formed during glycolysis?** A) Glucose-6-phosphate B) Fructose-6-phosphate C) Pyruvate D) Acetyl-CoA **Answer: Glucose-6-phosphate** 36. **Which molecule does glucose get converted into during glycolysis?** A) Acetyl-CoA B) Pyruvate C) Glucose-6-phosphate D) Lactic acid **Answer: Pyruvate** 37. **In what form are most fats stored in the body?** A) Triglycerides B) Phospholipids C) Cholesterol D) Fatty acids **Answer: Triglycerides** 38. **What is the main source of energy during the first 30 minutes of exercise?** A) Glycogen B) Fatty acids C) ATP D) Glucose **Answer: Glycogen** 39. **Which molecule is the final electron acceptor in the electron transport chain?** A) NADH B) FADH2 C) Oxygen D) Water **Answer: Oxygen** 40. **Where does the citric acid cycle (Krebs cycle) take place?** A) Cytoplasm B) Mitochondria C) Endoplasmic reticulum D) Nucleus **Answer: Mitochondria** 41. **Which of the following metabolic processes is responsible for synthesizing glycogen?**  A) Glycogenesis B) Glycolysis C) Gluconeogenesis D) Glycogenolysis **Answer: Glycogenesis** 42. **What is the main purpose of gluconeogenesis?** A) To break down glucose into pyruvate B) To produce glucose from non-carbohydrate precursors C) To store glucose as glycogen D) To generate ATP **Answer: To produce glucose from non-carbohydrate precursors** 43. **Which molecule is required for the transport of fatty acids into mitochondria for β-oxidation?** A) ATP B) Carnitine C) Coenzyme A D) Acetyl-CoA **Answer: Carnitine** 44. **Which of the following processes generates the most ATP per glucose molecule?** A) Glycolysis B) Citric acid cycle C) Electron transport chain D) Fermentation **Answer: Electron transport chain** 45. **Which molecule is produced in the citric acid cycle and is used in the electron transport chain?** A) Glucose B) Pyruvate C) NADH D) Lactate **Answer: NADH** 46. **What is the major role of coenzyme A in metabolism?** A) To transfer electrons in the electron transport chain B) To activate fatty acids for oxidation C) To transfer amino groups in protein metabolism D) To regulate gene expression **Answer: To activate fatty acids for oxidation** 47. **Where do the majority of ATP molecules come from in cellular respiration?** A) Glycolysis B) Citric acid cycle  C) Electron transport chain D) Fermentation **Answer: Electron transport chain** 48. **What molecule is required to form ATP in cellular respiration?** A) Oxygen B) NADH C) Glucose D) ADP and inorganic phosphate **Answer: ADP and inorganic phosphate** 49. **Which metabolic process occurs in the mitochondria and produces the most ATP per glucose molecule?** A) Glycolysis B) Citric acid cycle C) Electron transport chain D) Fermentation **Answer: Electron transport chain** 50. **Which molecule is the end product of anaerobic glycolysis?** A) Lactic acid B) Glucose C) Acetyl-CoA D) NADH **Answer: Lactic acid**