Form%204%20-%20Biology%20Notes

Form%204%20-%20Biology%20Notes - Biology Form 4 Notes...

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Unformatted text preview: Biology Form 4 Notes (2003-2004)2005 Jordan Mifsud (4.8) 5.8 Page 1 & & T OPIC 1: N UTRITION The 7 Basic Food Substances All the food we eat is made up of the following 7 basic substances: 1. Carbohydrates 2. Fats 3. Proteins 4. Vitamins 5. Minerals 6. Fibre 7. Water Carbohydrates , fats , proteins and vitamins are organic substances because they contain carbon in their molecular structure. Water and minerals are inorganic substances since they dont contain carbon . Carbohydrates, fats and proteins are needed in bulk in our diet, while vitamins and minerals are needed in smaller amounts. A person whose diet lacks any of these nutrients suffers from malnutrition , and this may give rise to a deficiency disease . Food gives us energy . The amount of energy needed by our body isnt the same for everyone . The amount of energy needed to live depends on the persons sex, job, attitude, age and other factors like if the person is a pregnant woman. 1. Carbohydrates Carbohydrates are organic substances made up of carbon , hydrogen and oxygen . They are very important because they provide energy for the body. There are 3 types of carbohydrates: sugars , starch , and cellulose . A. Sugars Glucose (C 6 H 12 O 6 ) Fructose (sugars in fruit) Sucrose (table sugar) Biology Form 4 Notes (2003-2004)2005 Jordan Mifsud (4.8) 5.8 Page 2 Glucose Molecule Lactose (found in milk) Maltose (found in barley grains) B. Strach Found in bread, potatoes, rice, cereals etc. Plants store food as starch. C. Cellulose Found in all unrefined plant food. An important source of fibre. Carbohydrates are all made up of molecules of glucose bonded (joined) together. The simplest form of carbohydrate is glucose. Two molecules of glucose joined together with a bond, form maltose , lactose and sucrose sugars. Starch, cellulose and glycogen are formed when 3 or more glucose molecules are joined together with bonds. Glucoses molecule is represented by a hexagon: A single sugar molecule is called a monosaccharide . Examples of monosaccharides are glucose and fructose . Sucrose , maltose and lactose are all disaccharides because they have 2 sugar molecules bonded together. Starch , cellulose and glycogen are all polysaccharides because they are made up of 3 or more sugar molecules bonded together. Biology Form 4 Notes (2003-2004)2005 Jordan Mifsud (4.8) 5.8 Page 3 Carbohydrates are found in cereals, pasta, bread, fruit, potatoes sugary food such as ice cream etc. Glucoses chemical formula is the following: C 6 H 12 O 6 . Plants store food as starch , while animals store food as glycogen . Both glycogen and starch are polysaccharides. Polysaccharides are NOT sweet but ARE insoluble ....
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Form%204%20-%20Biology%20Notes - Biology Form 4 Notes...

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