topic 2- organisation

• Food tests


  1. Prepare food sample

  2. Crush food with mortar and pestle

  3. Dissolve in distilled water

  4. Filter solution
• Sugars


  Small units that all carbohydrates are made of
• Types of sugars


  • Reducing sugars
  • Non-reducing sugars
• Benedict's test for reducing sugars


  1. Prepare food sample

  2. Transfer 5cm3 to test tube

  3. Heat in 75°C water bath for 5 minutes

  4. Add Benedict's solution
• Benedict's test


  • Tests for reducing sugars
  • Solution turns green, yellow or brick red if reducing sugars present
• Starch


  A type of carbohydrate, larger and more complex molecule than sugars
• Iodine test for starch

  1. Take 5cm3 of food sample

  2. Add iodine solution

  3. Solution turns blue-black if starch present
• Buret test


  Test for proteins
• Buret test for proteins


  1. Take 2cm3 of food sample

  2. Add 2cm3 of Buret solution

  3. Solution turns pink or purple if proteins present
• Lipids


  Tested using Sudan 3 and emulsion tests
• Sudan 3 test for lipids

  1. Take 5cm3 of food sample

  2. Add 3 drops of Sudan 3 stain

  3. Red layer forms at top if lipids present
• Enzymes


  Essential for helping us break down the large molecules that we eat into the much smaller soluble molecules that we can absorb through our intestinal lining
• Main groups of nutrients to be broken down

  • Carbohydrates
  • Proteins
  • Fats
• Carbohydrates


  Found mainly in foods like pasta, potatoes and rice, used by the body mainly as an energy source
• Starch


  The main type of carbohydrate
• Breakdown of starch


  Broken down by the enzyme amylase into smaller sugars such as maltose
• Places where amylase is made


  • Salivary glands
  • Pancreas
  • Small intestine
• Proteins


  Found in things like nuts, meats and beans
• Breakdown of proteins


  Broken down by protease enzymes into amino acids
• Places where proteases are made


  • Stomach (pepsin)
  • Pancreas
  • Small intestine
• Fats/Lipids


  Found in foods like cheese, oils and chocolate
• Breakdown of fats/lipids


  Broken down by lipase enzymes into glycerol and fatty acids
• Places where lipases are made


  • Pancreas
  • Small intestine
• All digestive enzymes are made by the pancreas and small intestine, with amylase also made by salivary glands and proteases also made in the stomach
• Cellular respiration


  An exothermic reaction which transfers energy from glucose and is continuously occurring in living cells
• Cellular respiration


  Breaking apart glucose molecules to release the energy that's trapped inside
• How organisms use their energy


  • Building up larger molecules from smaller ones (e.g. combining amino acids to form proteins)
  • Muscular contraction for movement
  • Maintaining body temperature
• Energy is needed for loads of reactions in our cells, most of which are catalyzed by enzymes
• Metabolism


  All the chemical processes that occur within a living organism in order to maintain life
• Aerobic respiration


  • More common type, takes place whenever there's enough oxygen, most efficient way to transfer energy from glucose, takes place continuously in both plants and animals, takes place within mitochondria
• Aerobic respiration


  Glucose + Oxygen -> Carbon dioxide + Water
• The equation for aerobic respiration is the opposite of the equation for photosynthesis
• Anaerobic respiration


  • Respiration without oxygen, used when there is not enough oxygen to keep up with the demands of aerobic respiration
• Anaerobic respiration


  Glucose -> Lactic acid
• Anaerobic respiration is less efficient because it involves incomplete breakdown of glucose and leads to lactic acid buildup
• Anaerobic respiration in plants and yeast


  • Glucose is converted to ethanol and carbon dioxide instead of lactic acid
  • In yeast, this process is called fermentation and is used to make bread, beer, and wine