Grade 11 Life Sciences Revision Material 2024 Term 2 PDF

Western Cape Education Department Directorate: Curriculum FET LIFE SCIENCES REVISION BOOKLET 2024 TERM 2 Grade 11 This revision program is designed to assist you in revising the cri...

Western Cape Education Department Directorate: Curriculum FET LIFE SCIENCES REVISION BOOKLET 2024 TERM 2 Grade 11 This revision program is designed to assist you in revising the critical content and skills that you have covered during the 2nd term. The purpose is to prepare you to understand the key concepts and to provide you with an opportunity to establish the required standard and the application of the knowledge necessary to succeed in the examination. The revision program covers the following topics: Photosynthesis (32 marks in Paper 1 in Final Examination) Animal nutrition (32 marks in Paper 1 in Final Examination) Cellular respiration (22 marks in Paper 1 in Final Examination)  2 Life Sciences revision booklet 2024 Grade 11 Term 2 Table of Contents 1. EXAMINATION WRITING TIPS:........................................................................................................... 4 1.1 GENERAL TIPS FOR WRITING LIFE SCIENCES:................................................................................. 4 1.2 HOW TO APPROACH YOUR LIFE SCIENCES EXAMINATION:........................................................... 4 TERM 2 CONTENT...................................................................................................................................... 5 2. PHOTOSYNTHESIS.............................................................................................................................. 5 2.1 PROCESS OF PHOTOSYNTHESIS..................................................................................................... 5 LIGHT PHASE:............................................................................................................................................. 6 DARK PHASE:.............................................................................................................................................. 7 2.2 IMPORTANCE OF PHOTOSYNTHESIS.............................................................................................. 7 2.3 ATP AS ENERGY CARRIER IN CELLS................................................................................................. 7 2.4 FACTORS THAT INFLUENCE THE RATE OF PHOTOSYNTHESIS........................................................ 7 2.5 THE ROLE OF OPTIMUM LIGHT, TEMPERATURE AND CARBON DIOXIDE IN A GREENHOUSE TO IMPROVE CROP YIELD................................................................................................................................ 9 2.6 EXPERIMENT TO SHOW THAT LIGHT IS NECESSARY FOR PHOTOSYNTHESIS................................. 9 3. ANIMAL NUTRITION......................................................................................................................... 10 3.1 DIFFERENCES IN DENTITION FOR HERBIVORES, CARNIVORES AND OMNIVOROUS LYFESTYLES10 3.2 HUMAN NUTRITION..................................................................................................................... 10 3.2.1 MECHANICAL DIGESTION......................................................................................................... 11 3.2.2 CHEMICAL DIGESTION.............................................................................................................. 12 3.2.3 ABSORPTION............................................................................................................................ 12 3.2.4 TRANSPORT AND ASSIMILATION OF ABSORBED NUTRIENTS.................................................. 13 3.2.5 EGESTION................................................................................................................................. 13 3.3 HOMEOSTATIC CONTROL - THE HORMONAL CONTROL OF BLOOD SUGAR LEVELS.................. 14 3.3.1 When the glucose levels in the blood increases above the normal level:............................... 14 3.3.2 When the glucose levels in the blood decreases below the normal level:.............................. 14 3.3.3 Diabetes mellitus:.................................................................................................................... 15 4. CELLULAR RESPIRATION................................................................................................................... 15 4.1 AEROBIC RESPIRATION................................................................................................................. 15 4.2 ANAEROBIC RESPIRATION............................................................................................................ 17 4.3 ROLE OF ANAEROBIC RESPIRATION IN THE INDUSTRY................................................................ 17 4.4 EXPERIMENT TO SHOW THAT CARBON DIOXIDE IS PRODUCED BY LIVING ORGANISMS DURING CELLULAR RESPIRATION........................................................................................................................... 17 5. REVISION QUESTIONS:..................................................................................................................... 18 QUESTIONS ON PHOTOSYNTHESIS.......................................................................................................... 18 QUESTIONS ON ANIMAL NUTRITION....................................................................................................... 21  3 Life Sciences revision booklet 2024 Grade 11 Term 2 QUESTIONS ON CELLULAR RESPIRATION................................................................................................. 23 END OF DOCUMENT................................................................................................................................. 24 List of figures (content only) Figure 1: Diagram showing the requirements and products of 5 photosynthesis Figure 2: Structure of a chloroplast 6 Figure 3: Flow diagram showing the light and dark phases of 6 photosynthesis Figure 4: Line graph showing the effect of light intensity -photosynthesis 7 Figure 5: Line graph showing the effect of carbon dioxide -photosynthesis 8 Figure 6 Line graph showing the effect of temperature – photosynthesis 8 Figure 7: Diagram showing that light is necessary for photosynthesis 9 Figure 8: The human digestive system 11 Figure 9: Structure of a villus 13 Figure 10: Flow diagram showing hormonal control of blood sugar 14 Figure 11: Structure of a mitochondrion 15 Figure 12: Diagram illustrating stages of aerobic respiration 16 Figure 13: Diagram to show that carbon dioxide is produced during 17 respiration List of tables (content only) Table 1: Instructional verbs and meaning 4 Table 2: Dentition in herbivores, carnivores and omnivores 10 Table 3: Types and functions of teeth in humans 12 Table 4: Enzymes involved in chemical digestion 12  4 Life Sciences revision booklet 2024 Grade 11 Term 2 1. EXAMINATION WRITING TIPS: 1.1 GENERAL TIPS FOR WRITING LIFE SCIENCES: The final external examination in Grade 11 consist of two (2) question papers of 150 marks each. Each question paper covers a variety of content topics. Ask your teacher for an outline of the content topics and weighting of each topic in each question paper. The duration of each of the final question papers in Grade 11 is 2½ hours. All questions in each question paper are COMPULSORY. You need to do all your drawings and graphs in pencil and labels should be in blue or black ink. You may not use graph paper when drawing graphs. Make sure that you have all the necessary stationery for your examination e.g. blue or black pens, a pencil, an eraser, a ruler, a non-programmable calculator, protractor and a compass. 1.2 HOW TO APPROACH YOUR LIFE SCIENCES EXAMINATION: Each Life Sciences question paper consists of TWO sections i.e. SECTION A (50 marks) and SECTION B (two questions of 50 marks) When answering a multiple choice question in Section A, read the question and four options carefully, evaluate each option and eliminate each incorrect option. In questions that require only a LETTER you only need to write down a LETTER e.g. ‘Give only the LETTER of the part where pollen is produced in the diagram of a flower’. Other questions might require you to write down both the LETTER and a NAME e.g. ‘Give the LETTER and NAME of the part of the flower in the diagram that receives the pollen’. Use the correct spelling when you use biological terminology in your answers. Use scientific names in terminology and avoid using common names. The instructional verbs (in italics) e.g. name, give, describe, explain etc. and the mark allocation per question give an indication of what and how much information you should provide in your answer. Table 1: Instruction verbs and meaning Instructional Meaning verb Name Give the name of something Differentiate Use differences to qualify between two or more categories Tabulate Draw a table and indicate the answers as direct pairs. Describe State in sentences the main points of a process Explain Give your answer in a cause-effect or statement and reason sequence Compare Give similarities and differences between concepts  5 Life Sciences revision booklet 2024 Grade 11 Term 2 TERM 2 CONTENT Study the core content below on the topics photosynthesis, animal nutrition and cellular respiration. 2. PHOTOSYNTHESIS Revise basic cell structure with focus on the chloroplast and leave structure from Grade 10. 2.1 PROCESS OF PHOTOSYNTHESIS ‘Photo’ means light and ‘synthesis’ means to produce. Photosynthesis is the process by which chlorophyll in the chloroplasts of green plants absorbs radiant energy from the sun, carbon dioxide from the atmosphere and water from the soil to produce carbohydrates (e.g. glucose) which is stored in the plant. Oxygen is released into the atmosphere during the photosynthesis. Enzymes in the cell are also needed for the process Excess glucose is converted into starch in the plant. The process of photosynthesis can be represented by the following equation: chlorophyll Carbon dioxide (CO2) + water (H2O) + radiant energy glucose + oxygen (O2) enzymes Figure 1: Diagram showing the requirements and products of photosynthesis Photosynthesis takes place in the chloroplasts of plant cells.  6 Life Sciences revision booklet 2024 Grade 11 Term 2 Figure 2: Structure of a chloroplast The process of photosynthesis occurs in two phases: Light phase: light is required Dark phase: no light is required Figure 3: Flow diagram showing the light and dark phases of photosynthesis. LIGHT PHASE: The light phase of photosynthesis takes place in the grana of chloroplasts. Radiant energy from the sun is absorbed by chlorophyll in the grana and transformed into chemical energy Chemical energy is used to to split water molecules (H2O) into energy -rich hydrogen atoms (H) and oxygen atoms (O). The process is known as photolysis. Energy rich hydrogen atoms are transferred to the dark phase. Oxygen is released into the atmosphere Radiant energy also causes the energy carrier ATP to be formed which will be used in the dark phase.  7 Life Sciences revision booklet 2024 Grade 11 Term 2 DARK PHASE: The dark phase of photosynthesis takes place in the stroma of chloroplasts. Carbon dioxide is absorbed from the atmosphere and combines with the energy-rich hydrogen atoms from the light phase using the energy that is released from ATP. Energy-rich carbohydrates (glucose) are formed. Excess glucose is stored as starch. 2.2 IMPORTANCE OF PHOTOSYNTHESIS Photosynthesis keeps the oxygen concentration in the atmosphere and water constant. Oxygen is needed by living organisms for cellular respiration. Photosynthesis keeps the level of carbon dioxide constant in the atmosphere and water. Carbon dioxide is released by organisms during cellular respiration. Photosynthesis provides food for heterotrophic organisms. 2.3 ATP AS ENERGY CARRIER IN CELLS When a cell needs energy ATP is broken down and the energy is released. Cells use this energy to produce important molecules such as proteins, fats etc. Muscle cells need energy provided by ATP to contract. Energy provided by ATP is needed to move substances across cell membranes. 2.4 FACTORS THAT INFLUENCE THE RATE OF PHOTOSYNTHESIS Light intensity At low light intensity, the rate of photosynthesis is low. As light intensity increases, the rate of photosynthesis also increases. This will happen up to a certain point. If light intensity increases above the optimum, the rate of photosynthesis will remain constant. Factors such as carbon dioxide become limiting factors which reduces the rate of photosynthesis Figure 4: Line graph showing the effect of light intensity on the rate of photosynthesis Carbon dioxide (CO2) concentration At a low carbon dioxide concentration, the rate of photosynthesis is low. As the carbon dioxide concentration level increases, the rate of photosynthesis also increases. This will happen up to a certain point.  8 Life Sciences revision booklet 2024 Grade 11 Term 2 If the carbon dioxide concentration is higher than the optimum amount, then photosynthesis will remain constant. Figure 5: Line graph showing the effect of carbon dioxide concentration on the rate of photosynthesis Temperature When temperature is low, the rate of photosynthesis is low. As temperature increases, the rate of photosynthesis also increases. If the temperature is higher than the optimum amount, then the rate of photosynthesis will decrease. This is because the enzymes used in the process will denature at high temperatures and will no longer function. At low temperatures enzymes become inactive. Figure 6: Line graph showing the effect of temperature on the rate of photosynthesis  9 Life Sciences revision booklet 2024 Grade 11 Term 2 2.5 THE ROLE OF OPTIMUM LIGHT, TEMPERATURE AND CARBON DIOXIDE IN A GREENHOUSE TO IMPROVE CROP YIELD A greenhouse is a structure with a glass or plastic roof in which farmers grow plants such as tomatoes. Warm air is trapped in a greenhouse. The aim of a greenhouse is to provide optimal conditions of light, temperature and carbon dioxide for maximum growth of plants. Optimum light intensity and temperature increases the rate of photosynthesis and stimulates the growth of plants. Carbon dioxide levels in the greenhouse decreases because of photosynthesis. Carbon dioxide gas can be pumped into a greenhouse to increase the rate of photosynthesis of the plants. 2.6 EXPERIMENT TO SHOW THAT LIGHT IS NECESSARY FOR PHOTOSYNTHESIS Destarch a potted plant by placing it in a dark cupboard for 48 hours Cover a portion of the leaf, still attached to the plant, with tinfoil Place the plant in a sunny area for 48 hours Pick the leaf and remove the foil Test for the presence of starch using iodine. The iodine solution remains light brown in the leaf covered with tin foil. The iodine solution turns blue-black in the parts that were left uncovered. The parts that turn blue-black in colour contain starch. The part which remains light brown does not contain starch. Figure 7: Diagram showing that light is necessary for photosynthesis  10 Life Sciences revision booklet 2024 Grade 11 Term 2 3. ANIMAL NUTRITION 3.1 DIFFERENCES IN DENTITION FOR HERBIVORES, CARNIVORES AND OMNIVOROUS LYFESTYLES Table 2: Dentition in herbivores, carnivores and omnivores Type of nutrition Dentition Herbivores Feed on plant material Large volumes of food are ingested, as plantmaterial has a low energy value Inscisors are sharp to cut off plant material Canines are usually absent Premolars and molars are large and flat to grind plant material Carnivores Feed on animal material Ingest less food as the proteins and fats in meat have a much higher energy value Inscisors have sharp ends to bite off food Canines are large to catch, hold and tear meat Molars and premolars have protusions with sharp edges to cut off food Omnivores Feed on both plant and animal material Amount of food consumed depends on the energy value of the food Similar teeth as carnivores but molars do not have such prominent protusions 3.2 HUMAN NUTRITION The digestive system is responsible for breaking down complex molecules into simplest forms to be absorbed into the body to sustain life. The human digestive system is made up of an alimentary canal (tube from mouth to anus) and accessory organs (e.g. liver, pancreas) that aid in the digestive process  11 Life Sciences revision booklet 2024 Grade 11 Term 2 Figure 8: The human digestive system 3.2.1 MECHANICAL DIGESTION During mechanical digestion food is broken down into smaller particles. Mechanical digestion includes: The chewing process (mastication) – food is broken down by the teeth and tongue Bolus formation – chewed food is mixed with saliva and rolled into a ball by the tongue. The tongue pushes the bolus down to the oesophagus Churning movements – this takes place by the contraction and relaxation of the muscles of the stomach wall. Food is broken down further and mixed with gastric juice Peristaltic movements – rhythmic contraction and relaxation of the muscles in the wall of the alimentary canal. It helps to move food particles forward.  12 Life Sciences revision booklet 2024 Grade 11 Term 2 Humans have four types of teeth with different functions: Table 3: Types and functions of teeth in humans Type of teeth Function Incisors Bite and cut off food Canines Hold food in place and tear it off Premolars Chew and grind the food Molars Chew and grind the food The human dental formula is: 2.1.2.3 2.1.2.3 3.2.2 CHEMICAL DIGESTION Chemical digestion is the breaking down of large, insoluble molecules in food into smaller, soluble molecules by the addition of water. The reaction is known as hydrolysis. Table 4: Enzymes involved in chemical digestion Substrate Enzymes End product of digestion Carbohydrates Carbohydrases e.g. salivary amilase Glucose (produced in mouth), Pancreatic amylase (produced in pancreas), Maltase, Sucrase, Lactase (produced in small intestine) Proteins Proteases e.g. pepsin and renin Amino acids (produced in stomach) and trypsin (in pancreas) Lipids Lipase (produced in pancreas and Glycerol and small intestine) fatty acids 3.2.3 ABSORPTION The end products of digestion i.e. glucose, amino acids, fatty acids and glycerol as well as vitamins, mineral salts and water are absorbed by the villi in the small intestine.  13 Life Sciences revision booklet 2024 Grade 11 Term 2 Figure 9: Structure of a villus The villi that are responsible for nutrient absorption are adapted for absorption in the following ways: The epithelium is only one-cell layer thick allowing nutrients to pass through quickly. Goblet cells secrete mucus to ensure the absorptive surface is moist and to allow nutrients to be dissolved and then to be absorbed. The epithelium contains many mitochondria to supply energy for active absorption of nutrients. Microvilli further increase the surface area. There is a lymph vessel called a lacteal in each villus which absorbs and transports lipids. 3.2.4 TRANSPORT AND ASSIMILATION OF ABSORBED NUTRIENTS Glucose, amino acids, vitamins, mineral salts and water are absorbed through the blood capillaries in the villi. The capillaries join to form large veins that eventually open into the hepatic portal vein The hepatic portal vein transports the absorbed nutrients to the liver where most of the glucose is converted into glycogen and stored. Excess amino acids undergo deamination in the liver to form urea and glucose. The urea is transported to the kidneys and excreted as part of urine The remaining glucose and amino acids leave the liver through the hepatic veins and are transported to the heart and to the rest of the body. The body cells absorb the required nutrients. This process is known as assimilation. 3.2.5 EGESTION All undigested materials are transported through the colon where most water and mineral salts are absorbed The undigested material is temporarily stored in the rectum until it is excreted through the anus. The undigested waste is then referred to as faeces  14 Life Sciences revision booklet 2024 Grade 11 Term 2 3.3 HOMEOSTATIC CONTROL - THE HORMONAL CONTROL OF BLOOD SUGAR LEVELS Figure 10: Flow diagram showing the hormonal control of blood sugar levels 3.3.1 When the glucose levels in the blood increases above the normal level: The pancreas is stimulated to secrete insulin into the blood Insulin is transported to the liver by the blood In the liver and muscles, the insulin stimulates the conversion of excess glucose into glycogen Insulin also stimulates the absorption of glucose from the blood into the body cells Glucose is removed from the blood and the glucose concentration in the body decreases 3.3.2 When the glucose levels in the blood decreases below the normal level: The pancreas is stimulated to secrete glucagon into the blood. Glucagon is transported to the liver by the blood In the liver and muscles, the glucagon stimulates the conversion of glycogen into glucose Glucose is released into the blood and the glucose concentration in the body increases.  15 Life Sciences revision booklet 2024 Grade 11 Term 2 3.3.3 Diabetes mellitus: A metabolic disease characterized by high glucose levels in the blood When insulin is absent or not functioning effectively, most of the glucose remains in the human body and this causes an increased blood glucose level, called hyperglycaemia. There are two types of diabetes: Type 1 diabetes – little or no insulin is produced and the person needs daily insulin injections Type 2 diabetes – the pancreas produces insulin but the body cells cannot use it effectively. The person needs oral medication or insulin. 4. CELLULAR RESPIRATION Cellular respiration is the chemical process where glucose is broken down gradually, in the presence of oxygen (aerobic respiration) or in the absence of oxygen (anaerobic respiration), to release energy. 4.1 AEROBIC RESPIRATION Aerobic respiration occurs in the presence of oxygen in the cytoplasm and the mitochondria of cells. The process of aerobic respiration can be represented by the following equation: enzymes Glucose + oxygen (O2) Carbon dioxide (CO2) + water (H2O) + ATP Figure 11: Structure of a mitochondrion  16 Life Sciences revision booklet 2024 Grade 11 Term 2 4.1.1 STAGES OF AEROBIC RESPIRATION Figure 12: Diagram illustrating the stages of aerobic respiration Glycolysis: Glycolysis occurs in the cytoplasm of the cell outside the mitochondrion Glucose is broken down into pyruvic acid Energy-rich hydrogen atoms are given off and move into the mitochondrion ATP is formed during glycolysis Krebs cycle: The Krebs cycle is a series of cyclic reactions that takes place inside the mitochondrion Pyruvic acid that entered the mitochondrion is broken down into energy-rich hydrogen atoms and carbon dioxide The carbon dioxide is released and given off as a gas Oxidative phosphorylation Oxidative phosphorylation takes place in the mitochondrion The energy from the hydrogen atoms is used to form energy-rich ATP The hydrogen atoms combine with oxygen to form water  17 Life Sciences revision booklet 2024 Grade 11 Term 2 4.2 ANAEROBIC RESPIRATION Takes place in the absence of oxygen Glucose is only partially broken down and less energy is released. Lactic acid fermentation– anaerobic respiration that occurs in muscle cells. Pyruvic acid is converted into lactic acid. Mucles become tired and painful. A small amount of ATP is produced. Alcoholic fermentation – anaerobic respiration that occurs in yeast cells. Carbon dioxide and alcohol(ethanol) is formed. 4.3 ROLE OF ANAEROBIC RESPIRATION IN THE INDUSTRY Yeast and other fungi respire anaerobically and are used to produce alcoholic beverages such as beer and wine. Yeast cells are also used to cause bread to rise during the baking process. The fermentation process is also used to produce cheese. Table 5: Comparison between aerobic and anaerobic respiration Aerobic respiration Anaerobic respiration Occurs in the presence of oxygen Occurs in the absence of oxygen Products are carbon dioxide and Products are lactic acid (animals) or water carbon dioxide and ethanol (plants/yeast cells) A large amount of energy is A small amount of energy is released released 4.4 EXPERIMENT TO SHOW THAT CARBON DIOXIDE IS PRODUCED BY LIVING ORGANISMS DURING CELLULAR RESPIRATION Figure 13: Diagram to show that carbon dioxide is produced by living organisms during respiration Use a small organism (e.g. snail). Sterilise the equipment so that no micro-organisms can influence the result. Place a snail in a large jar. Set- up the apparatus as shown in diagram above, making sure that the test tubes are tightly sealed.  18 Life Sciences revision booklet 2024 Grade 11 Term 2 Examine the test tubes the following day and record the results. The lime water remains clear in test tube B because carbon dioxide was removed by the soda lime and sodium hydroxide. The lime water turns milky in test tube D due to carbon dioxide produced by the snail. 5. REVISION QUESTIONS: Answer the questions below. Work through the questions in your lessons. Please note that HIGHER ORDER questions are in BOLD and marked with a (*) QUESTIONS ON PHOTOSYNTHESIS 1. The diagram below is a schematic representation of the process of photosynthesis. 1.1 Identify organelle A (1) 1.2 Name the following: (a) The phase represented by X (1) (b) The part of the organelle A in which the phase in QUESTION 1.1.2 (a) takes place. (1) 1.3* Explain THREE effects on living organisms if photosynthesis does not occur. (6)  19 Life Sciences revision booklet 2024 Grade 11 Term 2 2. The diagram shows a plant propagator in which scientists can control temperature, light intensity and carbon dioxide concentration: The scientists set different temperatures, CO2-concentrations and light intensities for four lettuce plants. A graphical illustration of the results is given below. The mean mass of lettuce plants serves as an indication of rate of photosynthesis.  20 Life Sciences revision booklet 2024 Grade 11 Term 2 2.1* What is the influence of light intensity on mean mass of lettuce plants? (2) 2.2* Name the TWO limiting factors that influence the rate of photosynthesis as the light intensity increases. (2) 2.3* How did the scientists increase the rate of photosynthesis to the maximum level? (2) 2.4* What would happen to the rate of photosynthesis if the temperature is raised beyond 35 °C? Give a reason for your answer. (4) 3. Study the following diagrams (A and B) which illustrate an investigation and answer the questions that follow. 3.1* State the aim of this investigation. (2) 3.2 Give ONE reason for each of the following steps in this investigation: (a) In the beginning of the investigation, the plant was kept in a dark cupboard for 48 hours. (1) (b) The leaf was boiled in water. (1) (c) The leaf was boiled in alcohol or methylated spirits. (1) 3.3 Draw a diagram of the leaf in stage B at the end of the investigation after it was treated with iodine solution and shade the parts which tested positive. (4) 3.4* State a conclusion for this experiment. (2)  21 Life Sciences revision booklet 2024 Grade 11 Term 2 QUESTIONS ON ANIMAL NUTRITION 4. Study the diagrams below of two animal skulls (A and B). 4.1 Identify which skull (A or B) belongs to a (a) herbivore (1) (b) carnivore (1) 4.2 Give ONE reason for your answer to QUESTION 4.1 (a) (1) 5. The diagram below shows parts of the human digestive system and its associated organs. 5.1 Identify parts B and G. (2) 5.2 Name ONE major food type that is digested in organ A. (1) 5.3 Name THREE features of part X which increase its surface area. (3) 5.4 State TWO advantages of part X having an increased surface area. (2)  22 Life Sciences revision booklet 2024 Grade 11 Term 2 5.5* Bacteria may infect the mucous lining of C. Explain what effect this might have on the digestive system of the infected person. (3) 5.6 Make a labelled drawing of the functional unit that is responsible for absorption in part F. (4) 5.7 Name the chronic health risk caused by the malfunctioning of part B. (1) 5.7 Describe the homeostatic role of part B when the blood sugar level in the human body rises. (5) 6. The graphs below show the effects of eating many small meals and eating fewer large meals on blood glucose and insulin concentrations in a normal person. The arrows on the graphs below indicate when meals were eaten. The normal blood glucose concentration is 100 mg/dl. 6.1 State what happens to the blood glucose concentration immediately after a meal is eaten. (1) 6.2* Use the information in the graphs. Tabulate TWO ways in which eating fewer large meals and eating many small meals affect the blood insulin levels differently. (5) 6.3* Explain why eating many small meals per day is better for a diabetic person than eating fewer large meals a day. (4)  23 Life Sciences revision booklet 2024 Grade 11 Term 2 QUESTIONS ON CELLULAR RESPIRATION 7. A group of learners set up an investigation as shown in the diagram below. 7.1* State the aim of the investigation? (2) 7.2 Give ONE reason why the seeds were sterilised before they were used. (1) 7.3* State ONE way how the learners could ensure the validity of the investigation (1) 7.4* State a suitable conclusion for the investigation above. (2) 7.5* Explain how they would set up a control for this investigation. (2)  24 Life Sciences revision booklet 2024 Grade 11 Term 2 8. An investigation was carried out with yeast cells which had been placed in two separate flasks. The contents of the flasks are indicated in the table below. Yeast Sugar Temperature Solution in Flask A 10g 20g 30ºC Solution in Flask B 10g 10g 10ºC The rate of respiration was measured by the number of gas bubbles released per minute. This was compared with the percentage alcohol per volume in each flask. The results are shown in the graph below. 8.1 Name the gas that was released by the yeast cells. (1) 8.2 State the rate of respiration when there was no alcohol in flask A. (2) 8.3 Give TWO factors which would have affected the rate of respiration in flask A. (2) 8.4* What effect does 21% alcohol have on the rate of respiration in Flask B? (2) END OF DOCUMENT