1 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
2 The loss of water vapor from the stomata is called: A Cuticular transpiration B Lenticular transpiration C Stomatal transpiration D Guttation
3 Which part of the chloroplast contains chlorophyll? A Stroma B Thylakoid membrane C Outer membrane D Intermembrane space
4 What is the function of root hairs? A To anchor the plant B To absorb water and minerals C To store food D To transport food
5 Which macronutrient is a key component of proteins and nucleic acids? A Phosphorus B Potassium C Nitrogen D Magnesium
6 What is the first stage of aerobic respiration? A Krebs cycle B Glycolysis C Electron transport chain D Fermentation
7 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.
8 Which gas is released during alcoholic fermentation? A Oxygen B Carbon dioxide C Nitrogen D Hydrogen
9 What is the role of potassium ions in guard cells? A They cause stomatal closure by increasing turgor. B They cause stomatal opening by increasing turgor. C They have no effect on stomata. D They cause stomatal closure by decreasing turgor.
10 Which factor can cause thermal denaturation of an enzyme? A Very low temperature B Optimum pH C High temperature D Low substrate concentration
11 What is the main function of root hairs? A To anchor the plant B To store food C To absorb water and minerals D To transport sugars
12 In which organelle does aerobic respiration mainly occur? A Chloroplast B Ribosome C Mitochondrion D Golgi apparatus
13 Which pigment absorbs red and blue light most effectively? A Chlorophyll a B Carotenoid C Chlorophyll b D Xanthophyll
14 In which form do plants store metabolic wastes like resins and gums? A In the vacuoles of cells B In the xylem vessels C In special excretory organs D By shedding leaves
15 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
16 Which of the following is a macronutrient required by plants? A Iron B Molybdenum C Calcium D Zinc
17 Where do the light-independent reactions (Calvin cycle) take place? A Thylakoid membrane B Stroma C Cytoplasm D Mitochondrial matrix
18 Which of the following is an industrial application of enzymes in the food industry? A Use of amylase in bread making B Use of catalase in paper production C Use of lipase in detergents D Use of protease in DNA replication
19 What is the optimum pH for most human enzymes? A Around pH 2 B Around pH 7 C Around pH 9 D Around pH 14
20 Which micronutrient is essential for the synthesis of chlorophyll in plants? A Iron B Magnesium C Nitrogen D Phosphorus
21 Which process allows water to move through a plant from roots to leaves? A Translocation B Transpiration C Photosynthesis D Respiration
22 Non-competitive inhibition occurs when an inhibitor binds to: A The active site B The allosteric site C The substrate D The product
23 Which theory explains the upward movement of water in the xylem of tall trees? A Pressure flow hypothesis B Cohesion-tension theory C Root pressure theory D Active transport theory
24 What is the effect of pH on enzyme activity? A Enzymes work best at any pH B Each enzyme has an optimum pH C pH has no effect on enzymes D Enzymes are permanently activated by extreme pH
25 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