BY2 - Nutrition

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  • BY2 - Nutrition
    • Methods of Nuritiion
      • Organisms need to obtain nutrients to provide energy to maintain life function.
      • Autotrophic Nutrition (Autotrophs)
        • Use inorganic molecules to synthesise organic compounds.
        • CCO2 + H20 --> Glucose
        • e.g. Plants/Algae
      • Heterotrophic Nutrition (Heterotrophs)
        • Organisms cannot make their own food.
        • Have to consume complex organic molecules, produced by autotrophs.
        • This is either done by autotrophs or other heterotrophs.
        • e.g. Animals/Fungi
      • Holozoic Feeders
        • Carnivores
          • Feed on other animals.
        • Herbivores
          • Feed solely on plant material.
        • Detritivores
          • Animals that feed on dead and decaying material.
        • Includes nearly all animals - food is broken down internally via digestion.
      • Saprophytes (Saprobionts)
        • Secretes enzymes onto food outside the body and absorb the products by diffusion (extracellular diffusion)
        • e.g. Bacteria
      • Parasites
        • Live in/on a host and obtain nourishment at the expense of the host.
        • e.g. Tapeworm
    • Digestion
      • The breakdown of large, insoluble molecules into smaller, soluble molecules by enzymes.
      • 4 Main Processes
        • 1. Ingestion
          • Taking food into the body via the mouth (or buccal cavity)
        • 2. Digestion
          • Chemical (enzymes) or mechanical (teeth or stomach) digestion.
        • 3. Absorption
          • Digested small, soluble molecules pass through the gut wall and into the blood.
        • 4. Egestion
          • Elimination of undigested food from the body.
            • e.g faeces or cellulose or bacteria or dead cells.
      • Structure of the Human Gut.
        • Outer Layer = Outer Serosa
          • Function: To protect the gut and reduce friction from other organs.
          • Strong
          • Made up of connective tissue.
        • 2nd Layer = Muscle
          • Inner circular muscles.
          • Outer longitudinal muscles.
          • Function: Peristalsis and to push food along the gut.
        • 3rd Layer = Sub-mucosa
          • Connective tissues containing vessels, nerve and lymph.
          • Function (Blood vessels and Lymph) - to take away or transport absorbed food products.
          • Function (Nerves) - coordinating peristalsis.
        • 4th Layer = Mucosa
          • Internal layer that lines the gut.
          • Secretes enzymes in some areas.
          • Secretes mucus to lubricate food and to protect the mucosa.
    • Parasites
      • Organisms that live in or on a host and obtain nutrients at the expense of the host.
      • Features of Pork Tapeworm (Taenia Solium)
        • Suckers or Hooks
          • Form an attachment to the gut of the host.
        • Large surface area to volume ratio.
          • Maximises absorption of nutrients because there is no digestive sytem.
        • Body Covering (Thick Cuticle)
          • Resistant to the host's digestive enzymes.
          • Protection from immune system of the host.
        • Hermaphrodite
  • Reproduces a large number of eggs.
    • Increases chance of survival.
    • Hermaphrodite
    • Increases chance of infecting a new host.

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