1 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
2 Which statement best describes the induced fit model of enzyme action? A The active site is a rigid shape that exactly matches the substrate. B The substrate changes shape to fit into the active site. C The active site changes shape slightly to fit the substrate more closely. D The enzyme and substrate do not interact directly.
3 What is a metabolic pathway? A A single enzyme-catalyzed reaction B A series of enzyme-controlled reactions in a cell C The movement of substances across a membrane D The breakdown of glucose without enzymes
4 In the paper industry, enzymes are used to: A Bleach paper B Break down starch to improve paper quality C Increase the strength of paper D Color the paper
5 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
6 Which factor does NOT directly affect enzyme activity? A Temperature B pH C Substrate concentration D Color of the container
7 In competitive inhibition, the inhibitor: A Binds to the allosteric site B Has a shape similar to the substrate C Permanently denatures the enzyme D Increases the active site's affinity for substrate
8 Which statement about enzyme specificity is correct? A One enzyme can catalyze many different types of reactions. B Enzymes are specific to their substrates due to the shape of the active site. C Enzymes are non-specific and work on any substrate. D Enzyme specificity depends on the temperature.
9 Which factor can cause thermal denaturation of an enzyme? A Very low temperature B Optimum pH C High temperature D Low substrate concentration
10 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
11 What is the primary function of enzymes in living organisms? A To provide energy for metabolic reactions B To act as biological catalysts and speed up chemical reactions C To store genetic information D To serve as structural components of cell membranes
12 In non-competitive inhibition, the inhibitor binds to: A the active site B the substrate C an allosteric site D the product
13 Which of the following best defines metabolism? A The breakdown of large molecules into smaller ones only B The sum of all chemical reactions in a living organism C The synthesis of large molecules from smaller ones only D The movement of substances across cell membranes
14 How do heavy metal ions inhibit enzyme activity? A By acting as cofactors B By binding to the active site and disrupting its structure C By increasing substrate concentration D By lowering the activation energy
15 Which of the following is true about intracellular enzymes? A They function outside the cell B They function inside the cell C They are always secreted D They are inactive at body temperature
16 The lock and key model of enzyme action was proposed by: A Daniel Koshland B Emil Fischer C Louis Pasteur D Charles Darwin
17 In competitive inhibition, how does the inhibitor affect the enzyme? A It binds to the allosteric site and changes the active site shape B It binds to the active site and blocks the substrate C It denatures the enzyme permanently D It increases the enzyme's affinity for the substrate
18 Which of the following is an example of an extracellular enzyme? A DNA polymerase B Amylase secreted by salivary glands C ATP synthase D Hexokinase
19 What happens to an enzyme when it is exposed to very high temperatures? A It becomes more active B It is permanently denatured due to disruption of bonds C It changes its specificity to a different substrate D It is converted into a substrate
20 At low substrate concentration, the rate of an enzyme-catalyzed reaction is directly proportional to: A Enzyme concentration B Substrate concentration C Temperature D pH
22 Which model explains enzyme action by stating that the active site is flexible and changes shape to fit the substrate? A Lock and Key Model B Induced Fit Model C Fluid Mosaic Model D Reflex Arc Model
23 Which of the following best describes the role of enzymes in metabolism? A They increase the activation energy of reactions. B They act as biological catalysts to speed up reactions. C They are consumed as reactants in metabolic pathways. D They provide energy for anabolic pathways.
24 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
25 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