B2 revision

• Enzymes

  Special proteins that act as biological catalysts
• Amylase

  • Breaks down starch into sugars
  • Made in the salivary glands and pancreas
  • Works in the mouth and small intestine
• Protease

  • Breaks down proteins into amino acids
  • Made in the stomach, pancreas and small intestine
  • Works in the stomach and small intestine
• Lipase

  • Breaks down lipids into glycerol and fatty acids
  • Made in the pancreas and small intestine
  • Works in the small intestine
• Enzymes

  • Specific, only break down substrates that fit their active site (lock and key principle)
  • Activity increases with temperature until the enzyme denatures
• Enzyme practical

  1. Mix amylase with starch and start timer

  2. Remove drops every 10 seconds and add iodine

  3. Iodine should turn black at first due to starch

  4. Record time taken for no starch to be detected

  5. Repeat at different temperatures or pH
• Optimum pH/temperature

  Between 2 lowest times
• Organisation process

  Cell to tissue to organ to organ system
• Digestion stages

  Mouth -> Oesophagus -> Stomach -> Pancreas -> Small intestine -> Large intestine -> Appendix -> Anus
• The pancreas produces all enzymes
• Digestion process ..

  1. Mouth - food chewed and swallowed

  2. Salivary glands - produce amylase

  3. Oesophagus - food travels to stomach

  4. Stomach - hydrochloric acid and enzymes kill bacteria and provide correct pH

  5. Liver - produces bile to neutralise stomach acids and break down fats

  6. Pancreas - releases enzymes into small intestine

  7. Gallbladder - stores bile

  8. Small intestine - food broken down further for absorption

  9. Rectum - faeces stored

  10. 10. Anus - faeces passed out of body
• An average adult has 4-6 litres of blood
• Red blood cells

  • Pass through capillaries
  • Contain haemoglobin made from iron
  • Do not have a nucleus
• White blood cells

  • Defend the body against harmful microorganisms (pathogens)
  • Make antibodies and antitoxins
• Red blood cells

  • Carry oxygen
  • Have a large surface area
• White blood cells

  • Fight off pathogens
• Platelets

  • Help blood clot (scab) to prevent bleeding
• Plasma

  Carries dissolved substances, 55% of blood
• Coronary heart disease

  Occurs when the artery supplying blood to the heart becomes blocked due to a build up of fatty deposits
• Risk factors for coronary heart disease

  • Overweight
  • Smoking
  • Physical inactivity
• Cardiovascular disease

  • Occurs when fat builds up in the arteries, restricting blood flow
  • Can be treated with stents to open up vessels or statins to reduce fatty deposits
• Chlorosis

  Magnesium deficiency
• Flower

  • Reproductive organs
• Transpiration

  Loss of water vapour through stomata
• Xylem

  Tubes that carry water and dissolved mineral ions upwards
• Transpiration rate

  Increased with air movement or temperature
• Meristem

  Stem cell production
• Leaf

  • Photosynthesis and gas exchange occur
  • Water evaporates out
• Phloem

  Tubes of cells that carry sugars around the body
• Roots

  • Water enters through osmosis
  • Mineral ions by active transport
• Nitrates are needed for protein synthesis
• Nitrate deficiency

  Stunted growth
• Communicable disease

  Caused by a pathogen, can spread
• Non-communicable disease

  Caused from inside the body, cannot spread
• Communicable diseases

  • HIV
  • Salmonella
  • Measles
  • Hepatitis
• Cancer

  Cells that divide continually and form into tumours
• Benign tumours

  • Grow slowly and do not spread
• Malignant tumours

  • Spread rapidly and invade
• Risk factors for cancer

  • Age
  • Weight
  • Genetics
• Starch test

  Iodine solution, orange to black