Organisation

• Cell to Organism

  1. Cells

  2. Tissue

  3. Organs

  4. Organ Systems

  5. Organism
• Tissues

  • Epithelial
  • Muscle
  • Glandular
• Organ Systems

  • Cardiovascular
  • Digestive
  • Reproductive
• Organ systems work together to form the organism
• Enzyme


  A biological catalyst that speeds up chemical reactions without being used up or changed
• Enzymes


  • Large proteins
  • Made by living organisms
  • Have a specific active site that binds to
• Induced fit model


  The enzyme actually changes shape slightly as it binds to the substrate
• Factors affecting enzyme action


  • Temperature (high temps break apart bonds holding enzyme together)
  • pH (affects enzyme's active site)
• Nutrients in a balanced diet


  • Carbohydrates
  • Lipids
  • Proteins
  • Vitamins
  • Minerals
  • Fibre
  • Water
• Carbohydrates


  • Made from atoms of carbon, hydrogen and oxygen
  • Can be broken down into simple sugars
• Proteins


  • Made from amino acids
  • Enzymes in stomach and small intestine break down proteins
• Lipids


  • Made of carbon, hydrogen and oxygen atoms
  • Not polymers (not formed from long chains of monomers)
• Digestion of carbohydrates, proteins and lipids

  1. Carbohydrates: Salivary glands, pancreas, small intestine

  2. Proteins: Stomach, small intestine

  3. Lipids: Pancreas, small intestine
• Bile emulsifies lipids, increasing surface area for lipase enzymes to break them down
• Digestive system


  1. Physical breakdown (chewing)

  2. Chemical breakdown (enzymes in saliva, stomach, small intestine)

  3. Absorption of digested food in small intestine

  4. Large intestine absorbs excess water to create faeces
• Digestive system

  1. Mouth
  2. Oesophagus
  3. Stomach - hydrochloric acid kills bacteria
  4. Small intestine
  5. Large intestine
  6. Rectum
• Food tests (Practical)


  1. Prepare food sample

  2. Break up food using mortar and pestle, put into beaker with distilled water, stir until some residues

  3. Filter solution to get rid of the solid bits of food
• Benedict's Test


  Tests for reducing sugars
• Benedict's Test


  1. Take 5cm^3 of food sample

  2. Prepare water bath at 75°C

  3. Add 10 drops of Benedict's solution to food sample

  4. Place in water bath for 5 mins
• Positive Benedict's Test


  Green, Yellow, Brick Red
• Iodine Test


  Tests for starch (carbohydrate)
• Iodine Test


  1. Add 5 cm³ of food sample to a test tube

  2. Add a few drops of iodine solution

  3. Shake gently
• Positive Iodine Test


  Orange -> blue black
• Biuret Test


  Tests for proteins
• Biuret Test


  1. Add 1 cm³ of food sample to a test tube

  2. Add 2 cm³ of Biuret solution

  3. Shake gently
• Positive Biuret Test


  Blue - Lilac
• Ethanol Test


  Tests for Lipids
• Ethanol Test


  1. Add 5 cm³ of food sample to a test tube

  2. Add 2 cm³ of ethanol

  3. Shake gently
• Positive Ethanol Test


  Colourless - cloudy
• The lungs provide oxygen for the body
• Gas Exchange


  1. Breathe in through mouth and trachea

  2. Into bronchi and then bronchioles

  3. Alveoli take up oxygen and give up carbon dioxide
• Alveoli


  • Very large surface area
  • Short diffusion pathway
• Alveoli adaptations


  Moist walls - allows gases to dissolve and diffuse more quickly

  1 thin layer of cells - short diffusion distance

  Very large surface area - increases rate at which co2 and o2 can diffuse across
• Coronary heart disease


  Coronary arteries become blocked by fatty material, lumen becomes narrower, less oxygen to the heart leading to heart attacks
• Treatments for coronary heart disease


  Stents - insert tube inside to hold artery open Benefits - surgery is quick, lasts a long time Issues - surgery has risks, blood clot near stent
• Statins


  Alter the balance of cholesterol, decrease bad (LDL) cholesterol, increase good (HDL) cholesterol
• Too much bad (LDL) cholesterol causes fatty deposits
• Issues with statins include side effects such as headaches and kidney failure, need to take regularly
• Faulty heart valves


  Can get damaged or weakened, treatment is to replace with a new one (biological or mechanical)
• Biological and mechanical heart valves both have issues, require surgery with risk of blood clots