organisation

• Carbohydrates are found in starchy foods like bread, pasta, and potatoes, as well as in fruits and vegetables
• Main reason we need carbohydrates is as an energy source
• Lipids refer to both fats and oils, with fats being solid at room temperature and oils being liquid at room temperature
• Found in foods like oily fish, nuts, seeds, dairy products, and avocados
• Main role is to provide energy and act as longer-term stores of energy
• Also keep us warm by insulating us and protecting our organs
• Proteins are found in nuts, seeds, meat, fish, and legumes (lentils, beans)
• Proteins act as building blocks for growth and repair of damaged tissue
• Can be used for energy in emergencies if there's a lack of carbohydrates or lipids
• Vitamins are organic molecules made by living organisms
• Vitamin A is needed for good vision and to keep skin and hair healthy (found in liver, leafy vegetables)
• Vitamin C prevents scurvy and is found in fruits like oranges (citrus fruits)
• Vitamin D helps absorb calcium and can be obtained from sunlight, eggs, and oily fish
• Minerals are inorganic and simpler molecules
• Calcium is found in dairy products and leafy vegetables, needed for strong bones
• Iron is important for hemoglobin in red blood cells, found in red meat, spinach, and beans
• Iron deficiency can lead to anemia, affecting oxygen transport in the body
• Fiber is a type of carbohydrate found in wholemeal foods, fruits, and vegetables
• Role of fiber is to help food move through intestines properly, preventing diarrhea or constipation
• Water is essential for the body, about 70% of our body is water
• We get water from drinks and foods, needed for various body functions including chemical reactions
• Continuous replacement of water is necessary as we lose it through breathing, sweating, and urinating
• To prepare a food sample for testing, you need to:

  • Break up the food using a mortar and pestle
  • Put the crushed food into a beaker with distilled water and stir until some dissolves
  • Filter out the solution using a funnel lined with filter paper to remove solid bits of food
• Benedict's test is for sugars:

  • Tests for reducing sugars
  • Prepare the food sample as mentioned earlier
  • Transfer 5 cm³ of the sample to a test tube
  • Add 10 drops of Benedict's solution
  • Place the test tube in a water bath at 75 degrees Celsius for 5 minutes
  • Color change indicates the presence of reducing sugars
• Iodine test is for starch:

  • Add a few drops of iodine solution to 5 cm³ of the food sample
  • Color change from brownish-orange to blue-black indicates the presence of starch
• Buret test is for proteins:

  • Add 2 cm³ of the food sample to a test tube
  • Add 2 cm³ of Buret solution
  • Gently shake the test tube
  • Color change from blue to pink or purple indicates the presence of proteins
• Sudan 3 test is for lipids:

  • Take 5 cm³ of the food sample
  • Add 3 drops of Sudan 3 stain solution
  • Gently shake the test tube
  • A bright red layer at the top indicates the presence of lipids
• Emulsion test for lipids (Edexcel course):

  • Take the food sample
  • Add 2 cm³ of ethanol and shake vigorously
  • Add an equal volume of distilled water
  • Cloudy white color indicates the presence of lipids
• Enzymes play a role in digestion by breaking down large molecules into smaller soluble molecules that can be absorbed through the intestinal lining
• Bile helps in digestion by neutralizing acids and emulsifying fats
• Carbohydrates, proteins, and fats are the three main groups of nutrients that need to be broken down during digestion
• Carbohydrates, found in foods like pasta, potatoes, and rice, are mainly used as an energy source
• Starch, the main type of carbohydrate, is broken down by the enzyme amylase into smaller sugars like maltose
• Amylase is produced in the salivary glands, pancreas, and small intestine
• Proteins, found in nuts, meats, and beans, are broken down by protease enzymes into amino acids
• Proteases are produced in the stomach (known as pepsin), pancreas, and small intestine
• Fats (lipids), found in foods like cheese, oils, and chocolate, are broken down by lipases into glycerol and fatty acids
• Lipase enzymes are produced only in the pancreas and small intestine
• All enzymes are produced by the pancreas and small intestine, with amylase also produced by salivary glands and proteases also produced in the stomach
• Humans need to eat carbohydrates (like starch and glucose), proteins, and fats for energy and metabolism