1 What happens to the rate of an enzyme-catalyzed reaction when all active sites are saturated? A It continues to increase linearly B It reaches a maximum and levels off C It decreases sharply D It stops immediately
2 Where does glycolysis occur in the cell? A Mitochondrial matrix B Cytoplasm C Inner mitochondrial membrane D Stroma
3 What is the function of a coenzyme? A To break down enzymes B To assist enzymes in catalyzing reactions C To serve as a substrate D To inhibit enzyme activity
4 Which part of the ATP molecule stores the energy that is released when ATP is hydrolyzed to ADP? A The adenine ring B The ribose sugar C The bond between the second and third phosphate groups D The bond between adenine and ribose
5 In which part of the mitochondrion does the Krebs cycle occur? A Outer membrane B Intermembrane space C Matrix D Cristae
6 Why is the induced fit model considered more accurate than the lock and key model? A It shows that the active site is rigid B It shows that the active site changes shape to fit the substrate C It shows that enzymes are not specific D It shows that substrates change shape to fit the enzyme
7 What happens to an enzyme when it is heated above its optimum temperature? A It works faster indefinitely B It becomes denatured C It changes into a substrate D It becomes an inorganic catalyst
8 Which of the following is an industrial application of enzymes in detergents? A Breaking down starch stains B Breaking down protein stains C Breaking down lipid stains D All of the above
9 Which stage of aerobic respiration produces the most ATP? A Glycolysis B Krebs cycle C Electron transport chain D Fermentation
11 What is the general chemical equation for photosynthesis? A 6CO2 + 6H2O → C6H12O6 + 6O2 B C6H12O6 + 6O2 → 6CO2 + 6H2O C 6CO2 + 6H2O → C6H12O6 + 6O2 + ATP D C6H12O6 → 2C3H4O3 + ATP
12 What is the active site of an enzyme? A A region where the substrate binds and undergoes a chemical reaction B The entire surface of the enzyme C A site where inhibitors always bind D A site that is not involved in catalysis
13 Which of the following is a use of enzymes in the food industry? A Production of antibiotics B Clarification of fruit juice C Manufacture of paper D Synthesis of nylon
14 What is a cofactor? A A protein that speeds up a reaction B A non-protein substance required for enzyme activity C A molecule that blocks the active site D A type of substrate
15 Which of the following best describes the 'lock and key' model of enzyme action? A The enzyme changes shape to fit the substrate B The substrate changes shape to fit the enzyme C The active site of the enzyme is complementary to the substrate shape D Enzymes are rigid and do not interact with substrates
16 Which model of enzyme action was proposed by Emil Fischer? A Induced fit model B Lock and key model C Fluid mosaic model D Saturation model
17 Which of the following is NOT a characteristic of enzymes? A They are specific to their substrates B They are consumed during the reaction C They are proteins (except some RNA molecules) D They lower the activation energy of a reaction
18 Which of the following is a product of the light-dependent reactions? A Glucose B Carbon dioxide C NADPH D Water
19 In which organelle does photosynthesis take place? A Mitochondria B Chloroplast C Nucleus D Ribosome
20 Which of the following is an accessory pigment in photosynthesis? A Chlorophyll-a B Chlorophyll-b C Carotenoids D Both B and C
21 What is the source of oxygen released during photosynthesis? A Carbon dioxide B Glucose C Water D ATP
22 Which of the following is an organic cofactor that is loosely attached to an enzyme? A Zinc ions B Coenzyme C Prosthetic group D Substrate
23 What is the primary function of the Calvin cycle? A To produce ATP B To produce NADPH C To fix carbon dioxide into glucose D To split water
24 Which pigment is the main photosynthetic pigment? A Chlorophyll-a B Chlorophyll-b C Carotenoid D Xanthophyll
25 Which pigment absorbs red and blue light most effectively? A Chlorophyll a B Carotenoid C Chlorophyll b D Xanthophyll