Gr11 LS 14 Exam Preparation Paper 1

Grade 11 Life Sciences: Exam Preparation Paper 1 Topics: 1) Energy transformation to sustain life: Photosynthesis 2) Animal nutrition 3) Energy Transformation: Respiration Revision of Key Concepts: 1) Energy transformation to sustain life: Photosynthesis

Revision Activity 1: Rapid Fire Questions: Round One-Photosynthesis Statement or description Term Raw materials required for photosynthesis 1 Process during photosynthesis when water molecules are 2 split up into hydrogen water The form of in which excess glucose is stored in plants 3 Reagent used to test for the presences of starch 4 Energy carrier that takes chemical energy to the dark 5 phase during photosynthesis Activity 2: An investigation was conducted to determine the relationship between light and the release of carbon dioxide by the leaves of plants grown in a sunny and shady area. The results are indicated in the graph below. Study the graph and answer the questions that follow.

However, before we attempt to answer these questions, let us try to understand exactly what the main concept of this experiment was all about. 2.1 At what range of light intensity is carbon dioxide released in plants that are grown in a sunny and shady area ? 2.2. Name the process, taking place in the leaves, which uses the carbon dioxide. 2.3. Why is most carbon dioxide released when the light intensity is zero units? 2.4 How much of carbon dioxide is taken up by the leaves grown in the sun when the light intensity is 60 units. 2.5 When the light intensity is approximately 10 units, there is no net change in the concentration of carbon dioxide surrounding the plant grown in the sunny area. Give and explanation for this. 2.6 At light intensities above 25 units in plants grown in shady areas, the amount of carbon dioxide remains the same. Suggest an explanation for this observation. 2.7 Name two external factors that need to be kept constant during this investigation.

Revision of Key Concepts: 2) Animal nutrition Rapid Fire Questions: Round two-Nutrition Statement or description Term The process in nutrition when food is changed from, 1 insoluble to soluble substances using enzymes Process in nutrition when undigested remains are 2 removed from the body Cells in the pancreas which secrete insulin and glucagon 3 The rhythmic contraction and relaxation of the muscle in 4 the wall of the alimentary canal that helps move the food particles forward A form of malnutrition due to the lack of protein in the 5 diet

Activity 3: (Nutrition) The following experiment was set up to test the effect of different pH values on the activity of protein- digesting enzyme normally found in the stomach of humans. Equal amounts of egg white (protein) and solutions of different pH values were placed in each of the four test tubes. All the test tubes were kept in a water bath at a constant temperature. 3.1 If 2 cm³ of the enzyme was added to test tube A, how much enzyme must be added to test tubes B and C? Give a reason for your answer. 3.2 In which test tube would you expect the egg white to be digested the fastest? Explain your answer. 3.3 Briefly discus the food test that you would conduct on the egg white to prove that it contained protein. 3.4 At temperature would you keep the water bath? Give one reason for your answer. 3.5 How would your experiment be affected if you added a few drops on concentrated sodium hydroxide to test tube A? Explain. 3.6 Would you expect a positive result for a protein test in D? Explain.

Revision of Key Concepts: Respiration Rapid Fire Questions: Round three- Statement or description Term The process in the body cells during which organic 1 compounds are broken down with the gradual release of energy Phase in cellular respiration when glucose is broken 2 down to pyruvic acid The use of living organisms in industrial processes such 3 food processing The liquid that becomes cloudy in the presence of carbon 4 dioxide Series of cyclic reactions during cellular respiration when 5 energy rich H-atoms and carbon dioxide are released

Activity 4: (Respiration) The diagram below represents the apparatus that was used in a practical investigation. After a period of 24 hours red hydrogen carbonate indicator was added to each test tube. Red hydrogen carbonate turns yellow in the presence of carbon dioxide. 4.1 Tabulate the results in terms of the colour of the water that may be observed in test tubes A, B and C respectively 4.2 What conclusion can be drawn from these results? 4.3 What is the purpose of test tube A? 4.4 Why were the test tubes kept in the dark? 4.5 Describe the expected results/observations and give an explanation for the observation in each of the following situations 4.5.1 test tube B, if a snail was added and the test tube was placed in the light 4.5.2 test tube C, if it was placed in the light.

Lesson 14: Exam Preparation Paper 1 Activity 1: Statement or description Term Raw materials required for photosynthesis Light; carbon dioxide and water 1 Process during photosynthesis when water molecules are photolysis 2 split up into hydrogen water The form of in which excess glucose is stored in plants Starch 3 Reagent used to test for the presences of starch Iodine 4 Energy carrier that takes chemical energy to the dark ATP 5 phase during photosynthesis Activity 2: 2.1 Sunny-5 units; shady 8 units 2.2. Photosynthesis 2.3. No photosynthesis occurring and thus only respiration that releases carbon dioxide. 2.4 20 units 2.5 The amount of carbon dioxide given off is equal to the amount of carbon dioxide taken in by the leaves. (Compensation point) 2.6 Plant has reached its maximum rate of photosynthesis; it has a specific concentration on chloroplast in the leaves and thus can only absorb up to a certain about of light; any further increase beyond this concentration will not influence the rate of photosynthesis and thus it remains constant. In addition, plants that grown in shade have few chloroplast in their leaves than plants adapted to growing in sunny areas. 2.7 Amount of water; temperature;

Rapid fire Questions 2: Rapid Fire Questions: Round two-Nutrition Statement or description Term The process in nutrition when food is changed from, Chemical digestion 1 insoluble to soluble substances using enzymes Process in nutrition when undigested remains are egestion 2 removed from the body Cells in the pancreas which secrete insulin and glucagon Islets of Langerhans 3 The rhythmic contraction and relaxation of the muscle in peristalsis 4 the wall of the alimentary canal that helps move the food particles forward A form of malnutrition due to the lack of protein in the Kwashiorkor 5 diet Activity 3: 3.1 2 cm³. To ensure that the volume is controlled and thus makes the experiment fair and reliable 3.2 Test tube A. pH 2 is an ideal pH for enzymes that work on proteins in the stomach. Other test tubes have pH ranges that will not allow protein-digesting enzymes to function optimally. D has the enzyme denatured also. 3.3 Biuret test. Proteins in the presences of biuret reagent turns from blue to purple/lilac when heated. 3.4 37-40˚C. Similar to human body temperature at which enzyme activity is optimum 3.5 Concentrated sodium hydroxide is a strong alkaline substance and will affect the pH of test A, causing it to change from pH 2 to probably 4 or 5. This will affect the optimum pH range for the enzyme and slow down or even stop the reaction. 3.6 Protein test will be positive; indicating the presences of proteins. Reason- the enzyme to digest the protein is denatured when it was boiled thus the enzyme does not digest the protein and will still be present to test positive.

Rapid fire Question 3: Statement or description Term The process in the body cells during which organic Cellular respiration 1 compounds are broken down with the gradual release of energy Phase in cellular respiration when glucose is broken glycolysis 2 down to pyruvic acid The use of living organisms in industrial processes such biotechnology 3 food processing The liquid that becomes cloudy in the presence of carbon Lime water 4 dioxide Series of cyclic reactions during cellular respiration when Krebs cycle. 5 energy rich H-atoms and carbon dioxide are released Question 4: 4.1 Test tube B C Colour of water Red Yellow Yellow 4.2 Both living organism, the water plant and the snail release carbon dioxide during cellular respiration. 4.3 Control, use to verify that organisms are responsible for the release of carbon dioxide 4.4 to prevent photosynthesis from occurring. 4.5.1 If the amount of carbon dioxide released by the snail is the same as the amount absorbed by the plant during photosynthesis, the indicator colour changes red. OR If the amount of carbon dioxide released by the snail is less than the amount absorbed by the plant during photosynthesis, the indicator changes purple OR If the amount of carbon dioxide released by the snail is more than the amount absorbed by the plant during photosynthesis, the indicator colour changes to yellow 4.5.2 the results will stay the same /no change snail will continue respiring, so high levels of carbon dioxide will be released therefore indicator turns yellow