Biology F4 Experiments

Chapter 2 – Cell Structure and Cell Organisation Apparatus       Number Pg. Title Activity 2.1 (Observation) 9 Preparing and examining slides of plant cells Aim / To prepare and study slides of Objective plant cells of the Study Material  Onion  Hydrilla sp.  Leaf  Iodine solution  Distilled water  Filter paper Apparatus  Light microscope  Glass slides  Cover slips  A pair of forceps  Scalpel  Dropper  Mounting needle Technique Prepare and stain wet mount of used specimens. Observe and draw the structures of plant cells using a light microscope. Light microscope Slides Cover slips Forceps Dropper Mounting needle Technique Prepare and stain wet mounts of used specimens. Observe and draw the structures of animal cells using a light microscope Movement of Substances across the Plasma Membrane Number Pg. Title Number Pg. Title Activity 2.2 (Observation) 10 Preparing and examining slides of animal cells Aim / To prepare and study slides of Objective animal cells of the Study Material  Methylene blue solution  Iodine solution  Toothpick  Distilled water  Cheek cells  Filter paper Activity 3.1 (Experiment) 20 The movement of substances across a semi-permeable membrane Aim / To study the movement of Objective substances across the Visking of the tubing Study Problem What factor influences the Statement diffusion of substances through a semi-permeable membrane? Hypothesis The diffusion of molecules through a semi-permeable membrane is based on the size of the molecule Variables  Manipulated variable: Size of the solute molecules in the Visking tubing  Responding variable: Colour of the solution in Visking tubing  Fixed variable: Time, volume of solutions and surrounding temperature Material  Benedict’s solution  1% starch suspension  Iodine solution  30% glucose solution  Distilled water Apparatus      Visking tubing Cotton thread Test tubes Beakers Water bath (Bunsen burner, tripod stand & wire gauze) Technique Test for the presence of starch used and glucose with iodine and Benedict’s solution respectively Apparatus           Number Pg. Title Activity 3.2 (Experiment) 23 Studying osmosis using an osmometer Aim / To demonstrate the process of Objective osmosis using simple osmometer of the Study Problem What substances can diffuse Statement through a semi-permeable membrane? Hypothesis Osmosis takes place when water moves from a region of low solute concentration to a region of high solute soncentration across a semi-permeable membrane Variables  Manipulated variable: Concentration of solution  Responding variable: Increase in the level of sucrose solution / The level of sucrose solution in the capillary tube  Fixed variable: Concentration of sucrose solution, surrounding temperature Material  30% sucrose solution  Distilled water 25 cm capillary tube Visking tubing Retort stand and clamp Cotton thread Ruler Marker pen A pair of scissors 250 ml beaker Syringe Stopwatch Technique Measure and record the increase used in the height of sucrose solution with a ruler. Number Pg. Title Activity 3.4 (Observation) 27 Studying the effects of hypotonic, hypertonic and isotonic solutions on animal cells Aim / To study the effects of hypotonic, Objective hypertonic and isotonic solutions of the on animal cells (red blood cells) Study Material  Fresh chicken blood  0.15 M sodium chloride solutions  0.50 M sodium chloride solutions  Distilled water  Filter paper Apparatus  Glass slides  Cover slips  Filter papers  Light microscope  Test tubes  Beakers  Dropper Technique Observe and study the effects of used hypotonic, hypertonic and isotonic solutions on animal cells from the slides by using microscope Number Pg. Title Activity 3.5 (Observation) 28 Studying the effects of hypotonic, hypertonic and isotonic solutions on plant cells Aim / To study the effects of hypotonic, Objective hypertonic and isotonic solutions of the on plant cells (cell sap of onion Study cells) Material  Onion bulb  0.5 M sucrose solutions  1.0 M sucrose solutions  Distilled water Apparatus  Light microscope  Glass slides  Cover slips  Razor blade / scalpel  A pair of forceps  Mounting needle  Filter papers Technique Observe and study the effects of used hypotonic, hypertonic and isotonic solutions on plant cells from the slides by using microscope. Hypothesis   Variables    Material                Apparatus  Number Pg. Title Activity 3.6 (Experiment) 30 Determining the concentration of an external solution which is isotonic to the cell sap of a plant Aim / To determine the concentration Objective of an external solution which is of the isotonic to the cell sap of a plant Study Problem What is the concentration of an Statement external (sucrose) solution which is isotonic to the cell sap of plants? Technique  used    The concentration of the solution which is isotonic to the cell sap of plant cells has no effect on the mass, length and size of plant cells. 0.36 M sucrose solution is isotonic to the cell sap of plants Manipulated variable: Concentration of sucrose solution Responding variable: Length of potato strips / Mass of potato strips Fixed variable: Volume of sucrose solution used, surrounding temperature and time Fresh potato Distilled water 0.1 M sucrose solution 0.2 M sucrose solution 0.3 M sucrose solution 0.4 M sucrose solution 0.5 M sucrose solution 0.6 M sucrose solution Petri dishes A pair of forceps Razor blade / Sharp scalpel Cork borer Ruler 50 ml beakers Electronic scale / electronic balance Tissue paper Measure the length of potato strips with ruler Determine the percentage difference in length Mass of potato strips with an electronic balance Determine the percentage difference in mass Chapter 4 – Chemical Composition of the Cell amylase is 37˚C Variables   Number Pg. Title Aim / Objective of the Study Material Activity 4.1 (Observation) 33 Differentiating between reducing and non-reducing sugars To differentiate between reducing and non-reducing sugars     Benedict’s solution Dilute hydrochloric acid Sodium hydrogen carbonate powder  10% glucose solution  10% sucrose solution Apparatus  Test tubes  Test tube holder  Beaker  Dropper  Bunsen burner  Tripod  Wire gauze Technique Carry out testing for the used presence of reducing sugars with Benedict’s solution Material                 Apparatus  Number Pg. Title Activity 4.3 (Experiment) 36 Studying the effects of temperature on salivary amylase activity Aim / To study the effects of Objective temperature on salivary of the amylase activity Study Problem What are the effects of Statement temperature on salivary amylase activity? Hypothesis The rate of reaction catalysed by salivary amylase is highest at 37˚C / The optimum temperature for salivary Technique  used  Manipulated variable: Temperature of medium of reaction Responding variable: The rate of reaction catalysed by salivary amylase Fixed variable: Volume of saliva, volume and concentration of starch suspension and pH of medium 1% starch suspension Saliva suspension Iodine solution Ice cubes Distilled water Beakers Test tubes Test tube rack Syringes Droppers Glass rods White tile with grooves Thermometer Bunsen burner Tripod stand Wire gauze Stopwatch Test the presence of starch using iodine test Record the time taken for the hydrolysis of starch to be completed. Number Pg. Title Activity 4.4 (Experiment) 39 Studying the effects of pH on the activity of pepsin Aim / To study the effects of pH Objective on the activity of pepsin of the Study Problem What are the effects of pH Statement on the activity of pepsin? Hypothesis An acidic medium at pH 3 is optimum for the activity of pepsin Variables  Manipulated variable: pH of medium  Responding variable: Rate of reaction catalysed by pepsin  Fixed variable: Volume and concentration of albumen suspension, volume and concentration of pepsin solution and temperature of medium Material  Egg albumen suspension  1% pepsin solution  0.1 M hydrochloric acid  0.1 M sodium hydroxide solution  Distilled water Apparatus  Beakers  Test tubes  Test tube rack  Droppers  Glass rod  Thermometer  5 ml syringes  pH paper  Bunsen burner  Tripod stand  Wire gauze  Stopwatch Technique Observe and record the used conditions of mixtures before and after 20 minutes Aim / Objective of the Study Problem Statement To study the effects of substrate concentration on salivary amylase activity Number Pg. Title Activity 4.5 (Experiment) 42 Studying the effects of substrate concentration on salivary amylase activity What are the effects of substrate concentration on salivary amylase activity? Hypothesis The rate of enzymatic reaction increases with the increase in substrate concentration until it reaches a maximum rate Variables  Manipulated variable: Substrate concentration / Concentration of starch suspension  Responding variable: Rate of reaction / Time taken for the hydrolysis of starch to be completed  Fixed variable: Enzyme concentration, pH of medium, volume of starch, volume of saliva suspension and surrounding temperature Material  0.1% starch suspension  0.2% starch suspension  0.3% starch suspension  0.4% starch suspension  0.5% starch suspension  0.6 % starch suspension  0.1% amylase solution / saliva suspension  Iodine solution Apparatus  Syringes  White tiles with grooves  Test tubes  Glass rod  Dropper  Measuring cylinder  Stopwatch  Beaker  Thermometer  Water bath (Bunsen burner, tripod stand and wire gauze) Technique  Test for the presence of used starch using iodine test  Record the time taken for the hydrolysis of starch to be completed with a stopwatch Technique  used  tripod stand and wire gauze) Number Pg. Title Activity 4.6 (Experiment) 43 Studying the effect of enzyme concentration on the activity of salivary amylase Aim / To study the effect of enzyme Objective concentration on the activity of of the salivary amylase Study Problem What are the effects of enzyme Statement concentration on the activity of salivary amylase? Hypothesis The rate of enzymatic reaction increases with the increase in enzyme concentration as long as there are no other factors limiting the rate of reaction. Variables  Manipulated variable: Enzyme concentration  Responding variable: Rate of reaction  Fixed: Substrate concentration and temperature Material  1% starch suspension  0.5% amylase solution / saliva suspension  Iodine solution  Distilled water Apparatus  5 ml of syringe  1 ml of syringe  White tiles with grooves  Test tubes  Glass rod  Dropper  Measuring cylinder  Stopwatch  Beaker  Thermometer  Water bath (Bunsen burner, Test for the presence of starch using iodine test Record the time taken for the hydrolysis of starch to be completed with a stopwatch Chapter 6 – Nutrition Number Pg. Title Activity 6.1 (Observation) 61 Determining the energy value in food samples Aim / To determine the energy value in Objective food samples of the Study Material  Peanut (whole)  Plasticine  Cotton wool  Distilled water Apparatus  Boiling tube  Thermometer (0 – 100˚C)  Pin (5 – 8 cm)  Bunsen burner  Retort stand and clamp  Wind shield  Electronic balance Technique  Measure and determine the used energy value in food samples (groundnut)  Measure the mass of the food samples by using electronic balance Number Pg. Title Aim / Modify from Activity 6.1 (Observation) 61 Determining the energy value in food samples To determine the energy value in Objective food samples of the Study Problem Which food sample has a higher Statement energy value? Hypothesis Cashew nut/ Walnut has a higher energy value that goundnut Variables  Manipulated variable: Type of food sample  Responding variable: Energy value of food samples  Fixed variable: Mass of water and mass of food sample Material  Fresh peanut (whole)  Fresh cashew nut / Fresh walnut (whole)  Plasticine  Cotton wool  Distilled water  Matches Apparatus  Boiling tube  Thermometer (0 – 100˚C)  Pin (5 – 8 cm)  Bunsen burner  Retort stand and clamp  Wind shield  Electronic balance Technique  Measure and determine the used energy value in different food samples  Compare the energy value in different food samples (groundnut and cashew nut / walnut)  Measure the mass of the different food samples by using electronic balance Aim / Objective of the Study Problem Statement To determine the vitamin C content in various fruit juices Number Pg. Title Activity 6.3 (Experiment) 65 Determining the vitamin C content in various fruit juices Do different types of fruit juices contain similar amounts of vitamin C? Hypothesis Lime juice contains a higher concentration of vitamin C compared to pineapple juice and orange juice. Variables  Manipulated variable: Types of fruit juices  Responding variable: Volume of fruit juice needed to decolourise DCPIP solution  Fixed variable: Volume of DCPIP solution and standard concentration of ascorbic acid solution Material  1.0% dichlorophenolindophenol (DCPIP) solution  0.1% ascorbic acid solution  Freshly prepared lime juice  Freshly prepared pineapple juice  Freshly prepared orange juice Apparatus  Specimen tubes  1 ml syringe  5 ml syringes with needles  50 ml beakers  Gauze cloth  Knife / Scalpel Technique  Measure and determine the used volume of standard vitamin C solution needed to decolourise of a fixed volume of DCPIP.  Measure and determine the volume of juice needed to decolourise the same volume of DCPIP.  Calculate the vitamin C content of juice by comparing it with the standard vitamin C solution.  Wire gauze Confirmation test for the presence of starch using iodine solution Confirmation test for the presence of reducing sugar using Benedict’s solution Technique  used  Number Pg. Title Activity 6.4 (Experiment) 67 Planning and conducting an experiment to study enzyme action on starch Aim / To study enzyme action on Objective starch of the Study Problem How does the enzyme in saliva Statement act on starch? Hypothesis The enzyme is saliva digest starch into a reducing sugar / The enzyme in saliva hydrolyses starch into a reducing sugar Variables  Manipulated variable: Absence or presence of salivary amylase and starch  Responding variable: Presence of reducing sugar  Fixed variable: Temperature at 37˚C, starch concentration and volume of mixture Material  1% starch suspension  Benedict’s solution  Iodine solution  Saliva suspension  Distilled water Apparatus  10 ml pipette  500 ml beaker  Test tubes  Test tube holder  Test tube rack  Thermometer  Droppers  Glass rod  White tile  Bunsen burner  Tripod stand Number Pg. Title Activity 6.5 (Experiment) 68 Planning and conducting an experiment to study the enzyme action on a protein food sample Introduction  Albumen does not dissolve completely in water  Albumen suspension is milky in nature. After albumen is fully digested, the suspension becomes clear  Pepsin requires an acidic pH of about 2 to act at maximum rate Aim / To study the enzyme action on Objective a protein food sample of the Study Problem How does the enzyme acts on Statement protein? Hypothesis  The test tube contains albumen and pepsin solution becomes clear at the end of the experiment  An acidic medium is needed for protein digestion by pepsin Variables  Manipulated variable: Absence or presence of pepsin in albumen  Responding variable: Cloudy or clear (clarity of contents) albumen suspension after 20 minutes  Fixed variable: Concentration and volume of albumen, concentration and volume of pepsin (enzyme), concentration of hydrochloric acid, surrounding temperature at 37˚C Material Albumen (egg-white) suspension  Dilute hydrochloric acid  Pepsin suspension  Distilled water Apparatus  10 ml pipette  500 ml beaker  Test tubes  Test tube rack  Droppers  Thermometer  Stopwatch  Water bath (Bunsen burner, tripod stand and wire gauze) Technique Observe albumen digestion used under the presence or the absence of pepsin and hydrochloric acid.  Variables    Material             Apparatus  Technique  used  Manipulated variable: Contents of the Visking tubing Responding variable: Change in colour of water sample in iodine test and Benedict’s test Fixed variable: Temperature of water bath (37˚C), volume of solution 1% starch suspension 1% glucose solution Iodine solution Benedict’s solution Visking tubing Thread Distilled water Boiling tube Test tubes 10 ml syringe Pipette A pair of scissors Water bath (Bunsen burner, tripod stand and wire gauze) Confirmation test for the presence of starch using iodine solution Confirmation test for the presence of reducing sugar using Benedict’s solution Number Pg. Title Activity 6.7 (Observation) 71 Studying the movement of substances through the Visking tubing Number Pg. Title Activity 6.11 (Experiment) 76 Investigating the effect of light intensity on the rate of photosynthesis Aim / To investigate the effect of light Objective intensity on the rate of of the photosynthesis Aim / Objective of the Study Problem What substances can move Statement across the Visking tubing? Hypothesis Small molecules can move across the Visking tubing Study Problem How does light intensity affect Statement the rate of photosynthesis? Hypothesis The higher the light intensity, the higher the rate of photosynthesis Variables  Manipulated variable: Distance between light source and plant  Responding variable: Number of bubbles released in five minutes (rate of photosynthesis)  Fixed variable: Type and size of plant, percentage of sodium hydrogen carbonate solution and voltage of bulb Material  A few sprigs of Hydrilla sp.  1% sodium hydrogen carbonate solution  Plasticine  Distilled water Apparatus  Light source (60 W bulb)  500 ml beaker  Test tube  Glass filter funnel  Stopwatch  Thermometer  Meter rule  Razor Technique Count the number of gas used bubbles released in five minute with a stopwatch Study Material Coloured liquid Living organism (cockroach) Soda lime Petroleum jelly (Vaseline) Water Apparatus  Boiling tubes  500 ml beaker  250 ml beakers  Capillary tubes  Rubber tubings  Screw clips  Ruler  Wire gauze Technique Measure and record the heights of used the coloured liquids in the capillary tubes with a ruler      Number Pg. Title Chapter 7 – Respiration Number Pg. Title Activity 7.1 (Observation) 83 Studying the process of aerobic respiration Aim / To study the process of aerobic Objective respiration of the Activity 7.2 (Experiment) 85 Investigate the process of anaerobic respiration in yeast Aim / To investigate the process of Objective anaerobic respiration in yeast of the Study Problem What are the products of Statement fermentation? Hypothesis In the absence of oxygen, yeast undergoes anaerobic respiration to produce carbon dioxide, ethanol and energy Variables  Manipulated variable: Presence of yeast  Responding variable: Changes on lime water and temperature  Fixed variable: Anaerobic condition Material  5% yeast suspension  5% glucose solution  Paraffin oil  Lime water Material Apparatus       Technique  used  Boiling tubes Test tubes Thermometers Stoppers with delivery tubes Measuring cylinders Beaker Record and measure the changes in temperature with thermometers. Observe the change in lime water. Potassium hydroxide solution  Potassium pyrogallate solution Apparatus  J-tube  Boiling tubes  Rubber tubing  Ruler  Washbasin Technique Measure and observe the length used of air columns occupied by gases in a J-tube with a ruler  Number Pg. Title Activity 7.6 (Experiment) 93 Investigating the difference between inhaled and exhaled air in terms of oxygen and carbon dioxide contents Aim / To investigate the difference Objective between inhaled and exhaled air of the in terms of oxygen and carbon Study dioxide contents Problem Are the contents of oxygen and Statement carbon dioxide in inhaled air the same as those on exhaled air? / does inhaled air contain the same amount of oxygen and carbon dioxide as exhaled air? Hypothesis Inhaled air has a higher percentage of oxygen when compared to exhaled air. Exhaled air has a higher percentage of carbon dioxide when compared to inhaled air. Variables  Manipulated variable: Inhaled air and exhaled air  Responding variable: Percentages of oxygen and carbon dioxide  Fixed variable: Method of analysis Number Pg. Title Activity 7.7 (Experiment) 96 Investigating the differences between inhaled and exhaled air in terms of heat content Aim / To investigate the differences Objective between inhaled and exhaled air of the in terms of heat content Study Problem Is the heat content in inhaled air Statement the same as that in exhaled air? Hypothesis Exhaled air has higher heat content when compared to inhaled air Apparatus  Thermometer Technique Measure and record the change used in temperature with a thermometer Number Pg. Title Activity 7.8 (Experiment) 97 Studying the effects of vigorous exercise on the breathing and heartbeat rates Aim / To study the effects of vigorous Objective exercise on the breathing and of the heartbeat rates Study Problem What is the effect of vigorous Statement exercise on the breathing and heartbeat rates? Hypothesis Vigorous exercise increases the breathing and heartbeat rates Variables  Manipulated variable: Resting or vigorous exercise  Responding variable: Breathing rate and heartbeat rate  Fixed variable: The type and duration of exercise, gender and age of the students Material Apparatus  Stopwatch Technique Count and record the number of used breaths per minute and the number of heartbeats per minute Technique Observe the effect of cigarette used smoke on lungs and increases the temperature of the respiratory tract. Tobacco tar makes the lungs appear brownish. Chapter 8 – Dynamic Ecosystem Number Pg. Title Number Pg. Title Activity 7.9 (Experiment) 99 Demonstrating the effects of cigarette smoke on lungs Aim / To show the effects of cigarette Objective smoke on lungs of the Study Problem What are the effects of cigarette Statement smoke on lungs? Hypothesis Cigarette smoke corrodes the cotton wool to change colour and contains acidic gas. Variables Material  Cotton wool  Universal indicator  Cigarettes Apparatus  U-tube  Thermometer  Boiling tube  Retort stand and clamp  Filter pump  Rubber tubing Activity 8.3 (Experiment) 108 Studying the intraspecific and interspecific competitions in plants Aim / To study the intraspecific and Objective interspecific competitions in of the plants Study Problem How do intraspecific and Statement interspecific competitions affect the growth of maize and rice plants? Hypothesis Intraspecific competition occurs between plants of the same species. Interspecific competition occurs between plants of different species. / The greater the competition among the seedlings, the greater the effect on the height of the seedlings. Variables  Manipulated variable: Types of seedlings  Responding variable: Dry mass of seedlings / Height of seedling  Fixed variable: Quantity and types of garden soil, amount of water, intensity of sunlight, distance between each seedling and number of seedlings Material  Three seedling trays (2 m x 1 m each) with garden soil  A packet of maize seeds  A packet of paddy seeds  Distilled water Apparatus       Ruler Oven Compression balance Spade Waterproof paint Paintbrush Technique Weight the dry mass of seedling used with an electronic balance / Measure the height of seedling with a ruler Variables Number Pg. Title Activity 8.7 (Experiment) 114 Studying the relationship of population distribution of an organism with the changes of an abiotic factor Aim To study the relationship of population distribution of an organism with the changes of an abiotic factor Introduction Pleurococcus sp. is a unicellular green alga found on the bark of trees. The population distribution ofPleurococcus sp.is affected by abiotic factors such as humidity, temperature, light intensity and aspect. Objective To investigate the effect of light of the Study intensity on the population distribution of Pleurococcus sp. in its habitat. Problem What is the effect of light Statement intensity on the population distribution of Pleurococcus sp.? Hypothesis The population distribution of Pleurococcus sp. is highest when there is optimum light intensity Manipulated variable: Light intensity  Responding variable: Total surface are covered by Pleurococcus sp.  Fixed variable: Temperature, pH and humidity Material  Paper Apparatus  Quadrat measuring 10 cm x 10 cm  A compass  Pen  Notebook Technique Quadrat sampling (estimate the used total surface area covered by Pleurococcus sp.)  Number Pg. Title Activity 8.11 (Experiment) 119 Studying the effects of temperature, pH, light intensity and nutrients on the activity of yeast Aim To study the effects of temperature, pH, light intensity and nutrients on the activity of yeast. Objective A) To study the effect of of the temperature on the activity of Study yeast. Problem What is the effect of temperature Statement on the activity of yeast? Hypothesis The activity of yeast is optimal at 37˚C Variables  Manipulated variable: Temperature of the water bath  Responding variable: Height of the coloured liquid in the manometer  Fixed variable: Volume of yeast suspension, pH, light intensity and time taken for the activity of yeast Material  Yeast suspension (4 g of yeast in 100 cm3 of glucose solution)  Coloured liquid  Ice cubes Apparatus  Boiling tubes  Beakers  Measuring cylinders  Glass tubes  Thermometers  Clips  Rubber stoppers  Rubber tubing  Manometer tubes  Strings  Ruler  Stopwatch  Water bath (Bunsen burner, tripod stand and wire gauze) Technique Measure and record the different used heights of coloured liquid in the manometer with a ruler. Objective B) To study the effect of pH on of the the activity of yeast. Study Problem How does pH affect the activity Statement of yeast? / What is the effect of different pH values in the activity of yeast? Hypothesis The activity of yeast is optimum in an acidic medium. Variables  Manipulated variable: pH  Responding variable: Height of the coloured liquid in the manometer  Fixed variable: Volume of yeast suspension, light intensity, temperature and time taken Material  Yeast suspension (4 g of yeast in 100 cm3 of glucose solution) -3  0.1 mol dm hydrochloric acid 0.01 mol dm-3 hydrochloric acid -3  0.1 mol dm sodium hydroxide solutions -3  0.01 mol dm sodium hydroxide solutions  Coloured liquid  pH paper  distilled water Apparatus  Boiling tubes  Beakers  Measuring cylinders  Glass tubes  Clips  Rubber stoppers  Rubber tubing  Manometer tubes  Strings  Ruler  Stopwatch  Retort stand Technique Measure and record the different used heights of coloured liquid in the manometer with a ruler. Objective C) To study the effect of light of the intensity on the activity of yeast. Study Problem How does the intensity of light Statement affect the activity of yeast? / What is the effect of light intensity on the activity of yeast? Hypothesis The activity of yeast is higher at a lower intensity of light. / The lower the light intensity, the higher the activity of yeast. Variables  Manipulated variable: Intensity of light  Responding variable: Height of coloured liquid in the manometer  Fixed variable: Volume of yeast suspension, pH, temperature and time taken Material  Yeast suspension (4 g of  yeast in 100 cm3 of glucose solution)  Coloured liquid Apparatus  Light bulb (60W)  Boiling tubes  Beakers  Measuring cylinders  Glass tubes  Clips  Rubber stoppers  Rubber tubing  Manometer tubes  Strings  Ruler  Stopwatch  Retort stand Technique Measure and record the different used heights of coloured liquid in the manometer with a ruler. Objective D) To study the effect of of the nutrients on the activity of yeast. Study Problem How do nutrients affect the Statement activity of yeast? / What is the effect of nutrients on the activity of yeast? Hypothesis The concentration of nutrients affects the activity of yeast. / The higher the concentration of nutrients, the higher the activity of yeast. Variables  Manipulated variable: Concentration of nutrients  Responding variable: Height of coloured liquid in the manometer  Fixed variable: Volume of yeast suspension, pH, light intensity and temperature Material  Dry yeast  5% glucose solution  10% glucose solution  15% glucose solution  Distilled water Apparatus            Boiling tubes Beakers Measuring cylinders Glass tubes Clips Rubber stoppers Rubber tubing Manometer tubes Strings Stopwatch Retort stand Technique Measure and record the different used heights of coloured liquid in the manometer with a ruler. Chapter 9 – Endangered Ecosystem Number Pg. Title Activity 9.1 (Experiment) 127 Comparing solid pollutants in the air of different environments Aim / To compare solid pollutants in Objective the air of different environments of the Study Problem Does the air of different Statement environments contain the same amount of solid pollutants? Hypothesis The air of different environments does not contain the same amount of solid pollutants. / The air from the most polluted environment has the highest amount of solid pollutants. Variables  Manipulated variable: Air from different environments  Responding variable: Amount of solid pollutants present  Fixed variable: Time and size of cellophane tape Material  Cellophane tape Apparatus    Slides Petri dish Microscope Technique Observe the amounts of solid used pollutants with a microscope Technique Measure and record the time used taken for the methylene blue solution to decolourise by using a stopwatch Number Pg. Title Activity 9.2 (Experiment) 128 Investigating the level of pollution in several different sources of water Aim / To investigate the level of Objective pollution in several different of the sources of water. Study  Industrial area  Housing area  From the hill / river  Distilled water (control) Problem What is the level of pollution in Statement several different sources of water? Hypothesis The water sample from the housing area drainage is the most polluted. Variables  Manipulated variable: water samples from different sources.  Responding variable: Time taken for methylene blue solution to decolourise  Fixed variable: Volume of water sample, size of reagent bottles, concentration and volume of methylene blue solution Material  Methylene blue solution  Water samples  Distilled water Apparatus  Reagent bottles (250 ml) with stoppers  Beakers  Syringes  Stopwatch