B3 - Transportation

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  • B3 - Transportation
    • Osmosis- The movement of water molecules across a partially permeable membrane, from a region of high water concentration to a low water concentration
      • Osmosis is a type of diffusion - passive movement of water.
    • Diffusion- - Where particles move from one area of high concentration to an area of low concentration.
      • Lungs transfer oxygen to the blood and to remove waste carbon dioxide.
        • They contain alveoli (gas exchange), which are specialised to maximise diffusion. Enormous surface area, moist lining, very thin walls, a good blood supply.
      • The inside of a small intestine contains millions of villi. They increase surface area so that digested food is absorbed quickly by blood.
        • They have a single layer of cells, and a very good blood supply to assist good absorption.
    • Active transport- Sometime substances need to be absorbed against a concentration gradient, i.e. from a lower to a higher concentration.
      • Root hairs- specialised: big surface area (hairs) to absorb water and mineral ions.
        • Concentration in root hair = higher.
        • AT allows plants to absorb minerals from a very dilute solution, against a concentration gradient. Essential for growth. Needs ENERGY from respiration to work.
      • Active transport is used in the gut when there is a low concentration of nutrients in the gut, but a high concentration in the blood.
    • Breathing system
      • Lungs are in the thorax (top part of your body). Separated by the diaphragm.
        • Breathing -  The air that you breath in goes through the trachea. Which splits into two 'bronchi' and then 'bronchioles' They end at small bags called alveoli, where the gas exchange take place.
      • Ventilation (breathing in). Intercostal muscles and diaphragm contract, thorax volume increases, decreases pressure and draws air in.
        • Breathing out -  muscles & diaphragm relax. Thorax volume decreases, increases pressure & air is forced out.
        • Artifical ventilators - machines that move air into or out of lungs. They help people who have lung injury or disease , or are under general anaestatic, so cant breathe by themselves.
    • Water flow through plants.
      • Phloem: Transport food. Made of columns of living cells with small holes in the end.
      • Xylem: carry water & minerals to the stem & leaves. Made of dead cells, joined end to end with no end walls between them & a hole down the middle.
      • Transpiration, is caused by evaporation & diffusion of water from inside the leaves.
  • Water moves into & out of Cells by Osmosis
    • Osmosis- The movement of water molecules across a partially permeable membrane, from a region of high water concentration to a low water concentration
      • Osmosis is a type of diffusion - passive movement of water.
  • Concentration in root hair = higher.
  • Breathing out -  muscles & diaphragm relax. Thorax volume decreases, increases pressure & air is forced out.
  • The inside of a small intestine contains millions of villi. They increase surface area so that digested food is absorbed quickly by blood.
    • They have a single layer of cells, and a very good blood supply to assist good absorption.

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