B2 - Organisation

• Benign tumor


  Growth of abnormal cells which are found in one area, contained within a membrane, do not invade or spread to other parts of the body
• Malignant tumor


  Malignant cells invade neighboring tissues, move into the bloodstream, spread to different parts of the body and form new tumors (secondary tumors)
• Malignant tumor cells are classed as a cancer
• Risk factors for developing cancer


  • Genetic (e.g. certain types of breast cancer, prostate cancer, cancer of the large intestine)
  • Lifestyle (e.g. lung cancer linked to smoking, skin cancer linked to UV exposure, mouth and throat cancer linked to alcohol)
  • Environmental (e.g. radon, a radioactive gas that increases risk of lung cancer)
• Radon releases ionizing radiation that damages DNA in cells, causing uncontrolled cell division leading to cancer
• Carrying out chemical tests for carbohydrates, proteins and lipids


  1. Grind food sample with distilled water using mortar and pestle to make a paste

  2. Transfer paste to beaker and add more distilled water

  3. Stir to dissolve chemicals

  4. Filter solution to remove suspended food particles
• Carbohydrates


  Include starch and sugars such as glucose
• Test for starch


  1. Place 2cm3 of food solution in test tube

  2. Add a few drops of iodine solution

  3. Blue-black colour indicates presence of starch

  4. Orange colour indicates no starch
• Test for sugars (e.g. glucose)


  1. Place 2cm3 of food solution in test tube

  2. Add 10 drops of Benedict's solution

  3. Heat test tube in hot water bath for 5 minutes

  4. Green colour = small amount of sugar

  5. Yellow colour = more sugar

  6. Brick red colour = a lot of sugar
• Reducing sugars


  • Sugars that the Benedict's test works for (e.g. glucose)
  • Non-reducing sugars (e.g. sucrose) do not work with Benedict's test
• Test for proteins


  1. Place 2cm3 of food solution in test tube

  2. Add 2cm3 of Biuret solution

  3. Purple/lilac colour indicates presence of protein
• Test for lipids/fats


  1. Grind food with distilled water using mortar and pestle (do not filter)

  2. Transfer 2cm3 of solution to test tube

  3. Add a few drops of distilled water and ethanol

  4. Shake gently

  5. White cloudy emulsion indicates presence of lipids
• Ethanol is highly flammable, so no naked flames should be present