Enzymes, Lipids, and Nucleic Acids PDF

Enzymes 1. What is the primary function of an enzyme? a) To increase activation energy b) To decrease activation energy c) To supply energy to the reaction d) To act as a substrate Answer: b) To decrease activation energy 2. Which part of the enzyme binds to the substrate? a) Active site b) Inhibito...

Enzymes 1. What is the primary function of an enzyme? a) To increase activation energy b) To decrease activation energy c) To supply energy to the reaction d) To act as a substrate Answer: b) To decrease activation energy 2. Which part of the enzyme binds to the substrate? a) Active site b) Inhibitor site c) Allosteric site d) Receptor site Answer: a) Active site 3. Enzymes are composed mainly of which type of macromolecule? a) Carbohydrates b) Lipids c) Nucleic acids d) Proteins Answer: d) Proteins 4. The specificity of an enzyme is due to its: a) Shape b) Temperature c) pH level d) Concentration Answer: a) Shape 5. Which of the following is a cofactor that assists enzyme function? a) Water b) Magnesium ion c) Glucose d) ATP Answer: b) Magnesium ion 6. Which type of enzyme catalyzes the removal of electrons or hydrogen atoms? a) Oxidoreductase b) Transferase c) Ligase d) Hydrolase Answer: a) Oxidoreductase 7. Competitive inhibitors bind to the enzyme at the: a) Allosteric site b) Active site c) Substrate d) Enzyme-substrate complex Answer: b) Active site 8. Which of the following factors does NOT directly affect enzyme activity? a) Temperature b) pH c) Substrate concentration d) Size of the enzyme Answer: d) Size of the enzyme 9. Which of the following describes an enzyme's saturation point? a) When the enzyme concentration exceeds substrate concentration b) When all enzyme active sites are occupied c) When substrate concentration is low d) When enzyme becomes denatured Answer: b) When all enzyme active sites are occupied 10. What is the effect of increasing substrate concentration on enzyme activity when the enzyme is saturated? a) Increases activity b) Decreases activity c) No effect d) Inhibits enzyme function Answer: c) No effect Lipid Structure and Function 11. Lipids are primarily composed of which elements? a) Carbon, hydrogen, and oxygen b) Nitrogen, carbon, and oxygen c) Sulfur, hydrogen, and oxygen d) Phosphorus, nitrogen, and carbon Answer: a) Carbon, hydrogen, and oxygen 12. Which of the following is a function of lipids in the body? a) Structural support b) Energy storage c) Enzyme catalysis d) Oxygen transport Answer: b) Energy storage 13. Which of the following is a characteristic of unsaturated fats? a) They contain only single bonds between carbon atoms b) They are typically solid at room temperature c) They contain one or more double bonds between carbon atoms d) They are found in animal products Answer: c) They contain one or more double bonds between carbon atoms 14. Which lipid is a major component of cell membranes? a) Cholesterol b) Phospholipids c) Triglycerides d) Steroids Answer: b) Phospholipids 15. Which of the following lipids is involved in signaling within the body? a) Triglycerides b) Phospholipids c) Steroids d) Fatty acids Answer: c) Steroids 16. A triglyceride consists of: a) Three fatty acids and a glycerol b) Two fatty acids and a phosphate group c) One fatty acid and a phosphate group d) Three glycerol molecules and one fatty acid Answer: a) Three fatty acids and a glycerol 17. The hydrophobic nature of lipids is due to: a) The presence of polar groups b) The absence of nitrogen c) The large number of C-H bonds d) The interaction with water molecules Answer: c) The large number of C-H bonds 18. Which of the following is a saturated fat? a) Olive oil b) Butter c) Sunflower oil d) Fish oil Answer: b) Butter 19. Lipids can be classified into three main groups: triglycerides, phospholipids, and: a) Glycolipids b) Proteins c) Nucleotides d) Steroids Answer: d) Steroids 20. Which of the following statements about cholesterol is true? a) Cholesterol is essential for cell membrane structure b) Cholesterol is a carbohydrate c) Cholesterol is only found in plant cells d) Cholesterol dissolves easily in water Answer: a) Cholesterol is essential for cell membrane structure Nucleic Acids Structure and Function 21. Nucleic acids are polymers made up of: a) Amino acids b) Nucleotides c) Monosaccharides d) Fatty acids Answer: b) Nucleotides 22. The backbone of a DNA molecule consists of: a) Amino acids b) Phospholipids and proteins c) Sugar and phosphate groups d) Fatty acids and glycerol Answer: c) Sugar and phosphate groups 23. Which nitrogenous base is found in RNA but not in DNA? a) Adenine b) Thymine c) Cytosine d) Uracil Answer: d) Uracil 24. The bond between nucleotides in a nucleic acid is called: a) Glycosidic bond b) Phosphodiester bond c) Hydrogen bond d) Ionic bond Answer: b) Phosphodiester bond 25. Which nucleic acid is responsible for carrying genetic information? a) RNA b) DNA c) rRNA d) tRNA Answer: b) DNA 26. The process of copying DNA into RNA is called: a) Replication b) Transcription c) Translation d) Mutation Answer: b) Transcription 27. What is the role of tRNA in protein synthesis? a) To carry genetic information from the nucleus to the ribosome b) To bind to amino acids and transfer them to the ribosome c) To synthesize proteins d) To replicate DNA Answer: b) To bind to amino acids and transfer them to the ribosome 28. Which of the following is a pyrimidine found in DNA? a) Adenine b) Cytosine c) Guanine d) Uracil Answer: b) Cytosine 29. Which enzyme is responsible for adding nucleotides to a growing DNA strand during replication? a) DNA ligase b) RNA polymerase c) DNA polymerase d) Helicase Answer: c) DNA polymerase 30. Which type of RNA carries the genetic code from DNA to the ribosome? a) tRNA b) mRNA c) rRNA d) snRNA Answer: b) mRNA 31. The two strands of DNA are held together by: a) Phosphodiester bonds b) Hydrogen bonds c) Ionic bonds d) Covalent bonds Answer: b) Hydrogen bonds 32. In RNA, adenine pairs with: a) Thymine b) Cytosine c) Guanine d) Uracil Answer: d) Uracil 33. The sugar found in DNA is: a) Ribose b) Deoxyribose c) Glucose d) Fructose Answer: b) Deoxyribose 34. Which of the following nucleotides is NOT found in RNA? a) Cytosine b) Thymine c) Guanine d) Adenine Answer: b) Thymine 35. The function of rRNA is to: a) Carry amino acids to the ribosome b) Form part of the structure of ribosomes c) Carry the genetic code d) Synthesize tRNA Answer: b) Form part of the structure of ribosomes 36. The double helix model of DNA was proposed by: a) Darwin and Mendel b) Watson and Crick c) Franklin and Pasteur d) Griffith and Avery Answer: b) Watson and Crick 37. During DNA replication, the leading strand is synthesized: a) Discontinuously b) In short fragments c) In the 5' to 3' direction continuously d) By ligase alone Answer: c) In the 5' to 3' direction continuously 38. Which of the following is a nucleic acid monomer? a) Glycerol b) Fatty acid c) Nucleotide d) Amino acid Answer: c) Nucleotide 39. Which type of bond forms between the base pairs in DNA? a) Hydrogen bonds b) Ionic bonds c) Covalent bonds d) Disulfide bonds Answer: a) Hydrogen bonds 40. Which of the following best describes the shape of a DNA molecule? a) Single helix b) Alpha helix c) Double helix d) Beta sheet Answer: c) Double helix Mixed Topics (Enzymes, Lipids, Nucleic Acids) 41. Enzymes that remove phosphate groups are known as: a) Kinases b) Phosphatases c) Ligases d) Isomerases Answer: b) Phosphatases 42. Which type of lipid forms the bilayer in cell membranes? a) Triglycerides b) Steroids c) Phospholipids d) Glycolipids Answer: c) Phospholipids 43. What is the correct pairing of nucleotides in DNA? a) A-C, G-T b) A-T, G-C c) A-G, T-C d) A-U, G-C Answer: b) A-T, G-C 44. Which factor does NOT affect the rate of enzyme activity? a) pH b) Substrate concentration c) Temperature d) Light intensity Answer: d) Light intensity 45. In RNA, which nucleotide replaces thymine? a) Guanine b) Cytosine c) Uracil d) Adenine Answer: c) Uracil 46. Which component of nucleic acids contains nitrogen? a) Phosphate group b) Nitrogenous base c) Sugar molecule d) Phosphodiester bond Answer: b) Nitrogenous base 47. Which lipid is essential for hormone synthesis? a) Cholesterol b) Phospholipid c) Glycolipid d) Triglyceride Answer: a) Cholesterol 48. Enzymes that digest lipids are called: a) Lipases b) Proteases c) Amylases d) Nucleases Answer: a) Lipases 49. In which part of the cell does DNA replication occur? a) Cytoplasm b) Ribosome c) Nucleus d) Endoplasmic reticulum Answer: c) Nucleus 50. Which enzyme is responsible for unwinding the DNA helix during replication? a) Ligase b) Helicase c) Primase d) Topoisomerase Answer: b) Helicase