IGCSE BIOLOGY 2014 Topic 2 – Animal Nutrition Macleans College Exam Survival Guide – Written by Pranesh Chand - Rutherford

Nutrition  Nutrition: taking in of nutrients which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating nutrients.  Carbohydrates: Carbon, Hydrogen, Oxygen  Fats: Carbon, Hydrogen, Oxygen  Proteins: Carbon, Hydrogen, Oxygen, Nitrogen and Sulphur (sometimes found).

Alternative to Practical – Paper 6. [Food Tests] Test Name:Presence of: Procedure:Positive Result: Negative Result: Iodine.StarchAdd few drops of Iodine onto a sample. Blue/Black Colour Orange Colour. Benedict Test.Simple Sugars/Reducing Sugars Add Benedict's Solution to Sample in a Test tube, and heat in a water bath. Green => Yellow=> Orange=> Brick Red. (Lowest to highest concentration). Blue Colour. Biuret Test.ProteinsAdd a few drops of Biuret Reagent to a sample in a test tube. Lilac Colour (Purple Colour) Blue Colour. Emulsion Test.Fats => LipidsAdd Ethanol, to the sample in a test tube and shake well. Solution becomes murky/unclear Solution remains clear.

Deficiencies in Diet  Deficiencies in diet are caused by inadequate portions of the mentioned nutrients below in a typical meal(s).  Vitamin C – Scurvy (Bleeding Gums); Yellowing of skin.  Vitamin D – Rickets (Weak Bones and teeth)  Calcium – Rickets (Weak Bones and teeth).  Protein – Kwashiorkor (Affects Children whose diets are lacking in protein. It causes Weakness and tiredness).  Iron – Anaemia (Less haemoglobin is formed which leads to less oxygen being transported and causes shortness of breath and; fatigue).

Monomers/Molecules Basic Units (Monomers) Larger Molecules Glucose – Simple SugarsStarch and Glycogen Amino Acids => 100s of Amino Acids (20 different types of Amino Acids). Proteins Lipids => 1xglycerol, 3x fatty acids Fats and Oils

Examples Of Nutrients in a typical Diet/meal NutrientSourceImportance: CarbohydratesRice, Potatoes, Sweets, bread etc. Energy FatsMeat, Milk, Eggs, Oil, Chocolate, etc. Energy, material for new cells, Energy Storage, Insulation to retain body heat, Protection for vital organs, steroid hormones ProteinsFish, Meat, Poultry, nuts, dry beans etc. Energy, material for new cells, making enzymes, hormones, antibodies Vitamin CFruits, Vegetables etc. Formation of Collagen and Immunity

Describe the uses, benefits and health hazards associated with food additives, including colourings:  Food Additives: Substances with no nutrient values, which are added to improve appearance, flavour, texture, and/or storage properties of food  But they have health implications for the user, and could results, in numerous health problems.  Food Additives, have reduced the chances of Food Poisoning, which has saved many lives.  Antioxidants, prevent food from reacting with oxygen, which could possibly change the taste and/or colour of the food.  An Example of Food Preservative : SO2 to control browning of potatoes.

Describe the use of microorganisms in the food industry, with reference to yoghurt and single cell protein.  Single-cell Protein(SCP): Sources of mixed protein extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria (Grown on agricultural wastes) used as a substitute for protein-rich foods, in human and animal feeds.  Excess yeast from alcoholic fermentation is sometimes used as cattle feed.  Fungi can be grown in a bioreactor to produce food for humans. This is called mycoprotein or Quorn.  Yoghurt: Sourced milk, partially clotted, with a mildly acidic taste = natural yoghurt. In Incubation, the culture of bacteria are kept at 45 c c and turn lactose into Lactic Acid during respiration, at 4 c c the reaction stops