Organisation

• Cells


  Make up all living things
• Tissue


  A group of specialised cells with a similar structure and function, can be made of more than one type of cell
• Tissue examples


  • Muscular tissue
  • Epithelial tissue
• Organ


  Formed from a number of different tissues, working together to produce a specific function
• Organ example


  • Stomach
• Organ system


  Organs organised to work together to perform a certain function
• Organ system example


  • Digestive system
• Organs in the digestive system

  • Glands (salivary glands, pancreas)
  • Stomach
  • Small intestine
  • Liver
  • Gall bladder
  • Large intestine
  • Rectum
  • Anus
• Enzymes


  Biological catalysts that increase the rate of reaction without being used up
• Enzymes


  • They can both break up large molecules and join small ones
  • They are protein molecules and the shape of the enzyme is vital to its function
  • Each enzyme has its own uniquely shaped active site where the substrate binds
• Lock and Key Hypothesis

  1. Substrate shape is complementary to active site shape, forming enzyme-substrate complex

  2. Reaction takes place and products are released
• Optimum pH


  The pH at which an enzyme works best, usually around 7 but some have a lower optimum pH
• Optimum temperature


  The temperature range around 37 degrees Celsius at which an enzyme works best
• Temperature increases


  Rate of reaction increases up to optimum, then rapidly decreases and stops
• pH too high or too low


  Changes the shape of the active site, enzyme is denatured and can no longer work
• Types of enzymes


  • Carbohydrases (convert carbohydrates into simple sugars)
  • Proteases (convert proteins into amino acids)
  • Lipases (convert lipids into fatty acids and glycerol)
• Benedict's test


  Test for sugars, turns brick red
• Iodine test


  Test for starch, turns blue-black
• Biuret test


  Test for protein, turns purple
• Emulsion test


  Test for lipids, add ethanol results in cloudy layer
• Sudan III test


  Test for lipids, red layer forms on top
• Bile


  • Produced in the liver, stored in the gallbladder, released into the small intestine
  • Alkaline to neutralise stomach acid
  • Emulsifies large fat droplets into smaller ones
• Investigating effect of pH on enzyme controlled reaction

  1. Use iodine to detect presence of starch

  2. Warm amylase, starch and buffer solution

  3. Take samples at regular intervals and observe iodine colour

  4. Time when starch is completely broken down

  5. Calculate rate using 1000/time
• Circulatory system


  Carries oxygen and nutrients to every cell in the body and removes waste products
• Double circulatory system


  Two circuits - deoxygenated blood to lungs, oxygenated blood around body
• Parts of the heart

  • Right atrium
  • Right ventricle
  • Left atrium
  • Left ventricle
  • Muscular walls
  • Valves
  • Coronary arteries
• Blood flow through the heart

  1. Blood flows into right atrium and left atrium

  2. Atria contract, forcing blood into ventricles

  3. Ventricles contract, pushing blood to lungs and around body

  4. Valves close to prevent backflow
• Pacemaker


  Group of cells in right atrium that provide electrical stimulation to make the heart beat
• Artificial pacemaker


  Electrical device that produces a signal to make the heart beat at a normal speed
• Types of blood vessels

  • Arteries (carry blood away from heart)
  • Veins (carry blood towards heart)
  • Capillaries (allow blood to flow close to cells)
• Lungs


  Supply oxygen to blood and remove carbon dioxide
• Parts of the gas exchange system

  • Trachea
  • Intercostal muscles
  • Bronchi
  • Bronchioles
  • Alveoli
  • Diaphragm
• Ventilation


  1. Ribcage moves up and out, diaphragm moves down, increasing chest volume and decreasing pressure

  2. Air drawn in from high to low pressure
• Gas exchange


  1. Oxygen diffuses from alveoli into blood

  2. Carbon dioxide diffuses from blood into alveoli
• Alveoli


  • Small and arranged in clusters for large surface area
  • Capillaries provide large blood supply
  • Thin walls for short diffusion pathway
• Blood


  Made up of plasma, red blood cells, white blood cells and platelets
• Components of blood


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Red blood cells


  • Biconcave disc shape for large surface area
  • No nucleus for more space to carry oxygen
  • Contain haemoglobin to bind oxygen
• White blood cells


  Part of the immune system, defend against pathogens
• Types of white blood cells

  • Those that produce antibodies
  • Those that engulf and digest pathogens
  • Those that coordinate the immune response