Mandatory Experiments Science Notes JC-Learn JC-Learn Science Notes Higher Level Mandatory Experiments 1 | P a g e Mandatory Experiments Science Notes JC-Learn Mandatory Experiments This folder includes every single experiment, which you must complete throughout the course. You must then write up these experiments in your experiments book and this is worth 10% of the exam. Biology Mandatory Experiment *To investigate the variety of living things by direct observation of plants and animals in their environment. To classify living things as plants or animals, and animals as vertebrates or invertebrates. Materials needed: Plant and animal identification books, plant and animal keys, notebook and pencil Method 1. Select area (school grounds) 2. Look for as many examples of plants and animals as you can find 3. Using identification books and keys, identify and name three plants and three animals within the area 4. Note which animals are vertebrates and which are invertebrates 5. Record the information Method 1. Use forceps to take small piece of inner skin of onion 2. Put drop of water onto glass slide, put piece of onion skin onto drop of water on slide 3. Lower cover slip over the onion skin (protects microscope lens) 4. Put slide onto microscope stage, under the clips 5. View the slide through the lens 2 | P a g e Mandatory Experiments Science Notes JC-Learn 6. Draw and label diagram of few cells under low power, then under high power 7. Remove slide from stage 8. Put drop of iodine stain under cover slip (stains the cytoplasm into yellow/brown colour) 9. Again examine under microscope, draw labeled diagram of this Mandatory Experiment 4 parts * (a) To test for the presence of starch. Apparatus needed: 2 test tubes, droppers, iodine solution, starch solution Method 1. Put 2cm3 starch solution in test tube 2. Put same volume of water in other test tube 3. Add two drops of iodine solution to both 4. Shake tubes, note colour change 5. Record results 6. Iodine is blue with starch, brown/yellow without it *(b) To test for presence of a reducing sugar (glucose) Apparatus needed: 2 test tubes, droppers, water bath, tripod, gauze, Bunsen burner, tongs, glucose solution, Benedict’s solution 3 | P a g e Mandatory Experiments Science Notes JC-Learn Method 1. Set up apparatus with water and benedicts solution in one, and glucose and benedicts solution in the other 2. Stand test tubes in boiling water bath for five mins 3. Record colour changes Results Tube with glucose solution goes brick-red colour, tube with water stays blue. Conclusion Appearance of brick red colour shows reducing sugar is present * (c) To test for presence of protein Apparatus needed: 2 test tubes, droppers, sodium hydroxide solution, copper sulfate solution, protein solution eg. milk Method 1. Set up two test tubes with milk and sodium hydroxide solution in one, and water and sodium hydroxide in the other 2. Add three drops of copper sulfate solution to each tube, mix the contents 4 | P a g e Mandatory Experiments Science Notes JC-Learn Results Mixture with milk turns violet coulour. The second test tube with only water stays blue. Conclusion Protein present in mixture with milk, not present in mixture with water. * (d) To test for the presence of fats Materials needed: brown paper, butter Method 1. Label two pieces of brown paper A and B 2. Rub butter on A 3. Put drop of water on B and rub it in 4. Allow both pieces of paper to dry 5. Hold each piece up to light, compare amount of light that passes through Results Place on paper where butter was rubbed will allow light pass through – translucent spot. Conclusion Fat is present on paper rubbed with butter. There is no change in paper rubbed with water – no light passes through it (fat not present). Mandatory Experiment To investigate the conversion of chemical energy in food into heat energy Apparatus needed: Bunsen burner, mounted needle, thermometer, boiling tube, graduated cylinder, retort stand, balance, cracker Method 1. Put 20cm3 water in test tube 2. Record temperature of water using thermometer 3. Stick mounted needle into cracker 5 | P a g e Mandatory Experiments Science Notes JC-Learn 4. Hold cracker in Bunsen flame until it catches fire 5. Transfer burning cracker under the water in boiling tube 6. Take temp of water again when cracker has burnt out 7. Record new temperature Result The temperature of the water will have risen. Conclusion The chemical energy in the cracker is converted into heat energy. Food contains energy. Mandatory Experiment *To investigate the action of amylase into starch. Apparatus required: droppers, graduated cylinder, Bunsen burner, tripod, gauze, beaker, thermometer, 4 test tubes, tongs, starch solution, amylase solution, iodine solution, Benedicts solution. In this experiment we want to see if amylase will break down starch. Method 1. Set up apparatus – two test tubes , one with starch and amylase while another has starch and water, placed in water bath at 37 degrees Celsius. 2. Leave both test tubes for five mins 3. Remove test tubes and place in rack 4. Place half contents of A into test tube C 5. Test contents of A for starch by adding iodine 6. Test contents of C for reducing sugars using Benedicts solution 7. Put half contents of B into test tube D 8. Repeat starch and reducing sugar tests on contents of B and D. Result It is only in test tube with amylase that starch has been broken down. Conclusion Amylase breaks down starch to reducing sugar. 6 | P a g e Mandatory Experiments Science Notes JC-Learn Mandatory Experiment *To compare the carbon dioxide levels of inhaled and exhaled air Method 1. Set up two test tubes, both with limewater – one with a tube coming out to suck in from and one with a tube coming out to blow out 2. Hold tube A (suck in from this one) and tube B (blow out from this one) 3. Suck in through tube A 4. Breathe out through tube B 5. Repeat steps until limewater in one goes milky and record result Result The limewater in test tube B turns milky quicker than A Conclusion The level of carbon dioxide in exhaled air is greater than the level of carbon dioxide in inhaled air 7 | P a g e Mandatory Experiments Science Notes JC-Learn Mandatory Experiment *To show that starch is produced by a photosynthesising plant. Apparatus required: beaker, Bunsen burner, tripod, gauze, forceps, test tube, white tile, alcohol, iodine solution, pot plant Method 1. Put pot plant in dark for 48 hours. This is necessary to de- starch the plant (without light, the plant cannot make any food and uses up its store of starch). 2. Cover part of some of leaves with aluminium foil 3. Leave plant in bright light for four to six hours (allows plant to photosynthesise). 4. Set up water bath with leaf in boiling water. 5. Remove one of the leaves with a foil strip and draw sketch of it to show position of foil strip. 6. Remove foil strip, drop leaf in boiling water for one minute to kill it. 7. Turn off Bunsen burner. 8. Half-fill a test tube with alcohol and push leaf into this test tube. 9. Stand test tube in warm water for ten minutes (chlorophyll removed so it is easier to see reaction of starch with iodine solution). 10. Use forceps to remove leaf from test tube (leaf will be white in colour). 11. Dip leaf in warm water to soften it. 12. Spread leaf onto white tile and cover with iodine solution (tests for presence of starch). 13. Draw new diagram of leaf showing where starch is present and compare it to first diagram. Results Part of leaf in light turns blue-black with iodine solution (shows starch is present). Part of leaf that was covered by foil stays brown-yellow (colour of iodine). This shows starch is not present. Conclusion 8 | P a g e Mandatory Experiments Science Notes JC-Learn Starch only found in part of leaf exposed to light. Therefore starch is produced by photosynthesis. 9 | P a g e Mandatory Experiments Science Notes JC-Learn Mandatory Experiment *To investigate the conditions necessary for germination. Apparatus required: 4 test tubes, cotton wool, cress seeds, oil, cool boiled water. Method 1. Set up four test tubes, as shown in the diagram, with cress seeds in each tube. 2. Boiling the water used in test tube C removes the oxygen from it. The layer of oil prevents oxygen getting back into the water. 3. Put test tubes A,C and D in warm place for a week. 4. Put test tube B in fridge for week. Results Test tube A: the cress seeds germinate. These seeds have all the conditions for germination. Test tube B: The seeds do not germinate. They have no warmth. Test tube C: The seeds do not germinate. They have no oxygen. Test tube D: The seeds do not germinate. They have no water. 10 | P a g e Mandatory Experiments Science Notes JC-Learn Mandatory Experiment * (a) To study a local habitat Method 1. Make map of habitat. 2. Record environmental factors affecting habitat. 3. Collect and identify plants and animals in habitat. 4. Use quadrat to examine variety of organism present. 5. Use line transect to investigate distribution of organisms across habitat. 6. Use the information to find examples of food chains, food webs, competition, adaptation and interdependence in the habitat. *(b) To show the variety of plants in habitat using a quadrat.