organisation - biology

• Cells are the basic building blocks of all living organisms
• Tissue


  A group of cells with similar structure and function
• Organ


  A group of tissues performing specific functions
• Organ system


  A group of organs performing a specific function
• Organism


  A group of organ systems together
• Enzymes


  Protein molecules found in cells that speed up reactions in the body
• Enzymes


  • They can be reused as their shape remains unchanged
  • They depend on their shape to work
• Lock and key model

  Explains how enzymes work - the substrate molecule (key) fits into the active site (lock) of the enzyme
• Metabolism


  Reactions that build up and break down molecules, controlled by enzymes
• Optimum temperature


  The temperature at which an enzyme works at its fastest rate
• Denaturation


  When the shape of the enzyme's active site is permanently changed, causing it to stop working
• Optimum pH


  The pH at which an enzyme works at its fastest rate
• Different enzymes have different optimum pHs
• Digestive system


  An organ system where several organs work together to digest and absorb food
• Key digestive enzymes


  • Carbohydrase
  • Lipase
  • Amylase
  • Protease
• Carbohydrase


  Enzymes that break down carbohydrates
• Amylase


  A type of carbohydrase that breaks down starch
• Protease


  Enzymes that break down proteins
• Lipase


  Enzymes that break down lipids
• Bile


  Produced by the liver, helps digest lipids by emulsifying them
• Iodine test


  Tests for the presence of starch - turns blue-black in the presence of starch
• Biuret test


  Tests for the presence of proteins - turns lilac in the presence of proteins
• Lipid test


  Tests for the presence of lipids - forms a cloudy white emulsion
• Benedict's test


  Tests for the presence of sugars - changes colour from blue to brick red
• Double circulatory system


  Blood is pumped to the body by the left side of the heart and to the lungs by the right side
• Parts of the heart

  • Left atrium
  • Left ventricle
  • Right ventricle
  • Right atrium
• Pacemaker


  Controls the resting heart rate by sending regular electrical impulses
• Artery


  Has a narrow lumen, thick muscle and elastic tissue layers to withstand high pressure
• Capillary


  Has very thin walls, only one cell thick, allowing for short diffusion distances
• Lumen


  The part inside where the blood is carried
• Arteries


  • Narrow lumen
  • Thick layer of muscle around the artery that can contract to pump blood
  • Thick elastic tissue layer that recoils and maintains pressure
• Capillaries


  The smallest blood vessels
• Capillaries


  • Very thin walls, only one cell thick
  • Allow for short diffusion distance for gas exchange
  • Very narrow, so red blood cells travel in single line
• Veins


  • Larger lumen compared to arteries
  • Thinner walls made of elastic and muscle tissue
  • Have valves to prevent backflow of blood
• Components of blood


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


  The liquid part of blood that transports dissolved substances
• Red blood cells


  Contain hemoglobin which carries oxygen, have a biconcave shape to increase surface area
• Platelets


  Small cell fragments that help blood to clot
• Blood is considered a tissue made of plasma in which red and white blood cells and platelets are suspended
• Coronary arteries


  Supply the heart muscle with oxygen and glucose