Microsoft word - 0610_y11_sw_2.docm

Scheme of work – Cambridge IGCSE® Biology (0610) Recommended prior knowledge Students can come into this unit with very little biological knowledge. However, they do need to understand some basic chemistry such as atoms, elements and compounds. An understanding of bonding and the role of ions in simple chemical reactions is an advantage. Context The molecules that make up the bodies of living things are introduced here, and will be referred to in all of the subsequent units. Outline This unit considers the molecules from which living organisms are made, and then looks in detail at how animals acquire the materials that they need to form the structure of their bodies, and also to supply energy. The way in which small molecules can be used to make larger ones is briefly considered, before thinking about how such large molecules need to be broken down again before they can be absorbed through the wall of the alimentary canal. The functions of the main digestive enzymes are considered, linking back to the work on enzymes in Unit 1. The use of food to supply energy will be covered in more detail in Unit 4, and the functions of the liver in glucose and amino acid metabolism, touched on very briefly here, will be treated in more depth in Unit 5. (Please note: (S) in bold denotes material in the Supplement (Extended syllabus) only) Discuss the need for materials for growth and repair and for energy to maintain their activities such as movement and sensitivity. A simple definition of an organic substance is one whose molecules contain carbon and hydrogen. Cross link with plant nutrition in Unit 3.1. Ensure that students have some understanding of the terms: Beads that string together, or simple chemical modelling kits, can be used to illustrate the idea of small molecules joining molecules from smaller basic units: A table or flash cards can identify the classes of foods. Headings: class of food; source of food; uses of food in body; Once Unit 1.11 is completed, the enzymes and products of digestion could also be added to the summary table. Students should understand that starch is the carbohydrate stored only in plants. Animals store carbohydrate as Students should have the opportunity to carry out each of these tests on a range of foods. It is a good practical lab in which students should realize the importance of safety when As an extension exercise, students can be given a solution containing a mixture of unknowns such as a reducing sugar This can also give useful practice in recording qualitative results in a clearly presented results chart. Conclusions can also be written from the observed results. Food tests also enhance the students' understanding of the • Describe the deficiency symptoms The information on multivitamin tablet packets lists the vitamin contents and their requirements in the human body. Extension – students could carry out research into food composition using the site Nutrition.gov A summary table could be produced with vitamins and minerals, their source, function in the body and details of deficiencies. Student progress could be assessed using: May/June 2011 Paper 0610/22 question 6b Oct/Nov 2009 Paper 0610/02 question 3 Students can make yoghurt in the lab and should discuss the importance of sterile apparatus and of the constant The use of yeast for bread making can be linked to anaerobic Students can vary the mass of yeast in a given volume of water that is added to a constant mass of flour to measure the Revision – Fermentation: increase in height of flour in a large test tube or plastic cup over time. Temperature or sugar can also be used as a variable. A good source of ideas for this is the booklet Student progress could be assessed using: The health benefits of preservatives, in terms of greatly reduced risk of food poisoning, should be emphasised. Antioxidants also increase storage times for many foods. Flavourings and flavour enhancers increase palatability. A few artificial colourings, such as tartrazine, have been associated Student progress could be assessed using: Diets in most countries depend on a staple food such as bread, potatoes or rice, which is usually the main source of carbohydrate. Students should be aware of the main sources of each type of nutrient in their own country, but also be prepared to consider how diets differ in other parts of the Extension – the Association for Science Education has a project called Science Across the World, which includes a unit about-food-food-nutrition-and- on diet, and encourages schools in different parts of the world Students can keep a record of the food that they eat during a short period of time and then consider whether they are obtaining the nutrients that they need. Their diet could be analysed using standard food tables or by accessing the nutrient data laboratory. Alternatively students could use the www.bbc.co.uk/learningzone/clips/a-well-balanced- www.bbc.co.uk/learningzone/clips/a-balanced-diet/10609.html Malnutrition should be considered as the result of eating an unbalanced diet, not just the lack of a particular type of • Describe the effects of malnutrition Controlled discussion on malnutrition can be useful and the problems associated with starvation can be linked to Unit 10.1 The long term problems associated with obesity like onset Students could take part in the Science Across the World – Student progress could be assessed using: Revision – Malnutrition: lgfl.skoool.co.uk/content/keystage4/biology/pc/modules/digestion/m Material to illustrate this topic, and to form the basis of • Discuss the ways in which the use discussion, can be collected from newspaper and television reports. Students may like to consider whether new technologies, such as the development of genetically modified brary/resource/1725/how-plants- varieties of crops, are likely to improve the situation or Extension – students could consider “food miles”. Student progress could be assessed using: Links with Unit 10 – Human influences on the environment Drought and flooding can be linked to Unit 10.1. Student progress could be assessed using: Students often do not understand that the alimentary canal is a long tube - albeit a coiled one - through substances e.g. food and drink into which food passes. A long flexible rubber tube can demonstrate the idea. A schematic diagram on A3 paper can clarify the main events that take place from ingestion by the mouth to egestion from Arrows in different colours can show which enzymes are Students should understand that food cannot be considered to have entered the body until it crosses the wall of the canal. The need for digestion to take place before absorption occurs is shown by using Visking tubing (to represent the alimentary canal) containing a mixture of glucose, starch and water. The visking tubing is placed in a beaker or a large test tube of water (to represent the blood), and left for several hours to allow the glucose to diffuse across the tubing. The contents of the tubing and of the beaker can be tested for - large intestine: colon and rectum starch and for glucose. Extension – the importance of active uptake could be considered. This is particularly important for students studying Cross reference 6.3.4 to 6.3.7 inclusive. Student progress could be assessed using: Extension – different types of teeth could be studied and Outline the role of bile in emulsifying fats, to increase the surface area for the action of enzymes Although most health professionals strongly support the • Describe how fluoride reduces addition of fluoride to water supplies, there are also some Student progress could be assessed using: This topic should be linked with earlier work on enzymes, in Students could draw a spider diagram of the alimentary canal. 4/biology/pc/modules/digestion/di This can help them visualise from where the enzymes are secreted and where they act on specific substrates. The importance of optimum pH and temperature should be emphasized, as well as the importance of enzymes in the Student progress could be assessed using: Core students do not need any detail of the villus structure but Biology for IGCSE, Williams et al. they need to understand that the dissolved substances, glucose and amino acids, are transported in the blood to the liver before they can be assimilated into the body. It helps the students to understand the importance of diffusion if the villus is compared with the alveoli in the lungs, Unit 4.4 The two structures can be compared as having a single cell • Describe the significance of villi in membrane, good blood supply, moist surface area and a large surface area for efficient diffusion. The absorption of glucose should be linked with earlier work Student progress could be assessed using: Identify the role of the small intestine and colon in the absorption of water (the small intestine absorbs 5-10 dm3 per day, the colon 0.3-0.5dm3 per day) For Core students, no detail of the hormonal control of glucose levels is required. They should, however, know that the liver stores excess glucose as glycogen (link back to Unit molecules into the cells of the body 2.2) and converts this back to glucose again if blood glucose The conversion of excess amino acids to urea should be dealt with very simply; this will be covered again in Unit 5.4. Extension – the importance of the liver could be highlighted – The destruction of excess amino by looking at causes and effects of liver failure. Student progress could be assessed using: The importance of nitrogen in the body could be discussed in Student progress could be assessed using: energy from the remainder of the amino acid

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