B3- Principles of organisation and The digestive system

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  • Created on: 18-04-22 17:21
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  • B3- Principles of organisation
    • Tissues and organs
      • Tissue- group of cells with simialr structure and function.
      • Organs- made up of tissues. 1 organ may contain several tissues.
      • Organ systems- groups of organs that perform a particular function.
      • Cells -> tissue -> organ -> organ system -> organism
      • Muscular tissue- can contract to bring about movement.
        • Glandular tissue- contains secretory cells e.g. hormones.
          • Xylem and Phloem- carry water and dissolved minerals.
    • Digestive system
      • Enzymes
        • Long chains of amino acids in enzymes are folded to produce a molecule with a specific shape.
          • This shape allows a molecule (SUBSTRATE) to fit into the enzyme.
            • FACTORS that affect rate of reaction: temperature, pH, enzyme concentration, substance concentrationm surface area and pressure.
              • All enzymes work best at only one particular temperature and pH.
                • This is called the optimum.
      • Organs
        • Stomach- breaks down the food and turns it into liquid.
          • Muscular stomach walls- Contracts and beats up the food. It can release acid.
        • Small intestine
          • Dissolves the fats by bile, breaks down molecules and absorbs.
            • Bile helps it dissolve fats. Villi help absorbtion and enlarge surface area
        • Large intestine
          • Drains out the remaining liquid and absorbs water. Turns it into stool.
        • Oesophagus
          • Carries down the food into the stomach by muscular contractions.
            • Adaptations- nerves, muscualr contractions and its long tube. Peristalsis.
        • Mouth
          • Breaks down food by using our teeth with saliva. Grinds food up.
            • Adaptations: salivary glands, teeth, saliva and our jaw muscles to help break the food.
    • Enzymes
      • The chemical reactions that take place in living cells happen at relatively low temperatures.
        • The rate of these enzyme controlled reactions increases with an increase in temperature.
          • Only true up to 40 degrees. After this the protein srtructure of the enzyme is affected and the shape of the active site is changed. The enzymes have been denatured.
      • Carbohydrase
        • Made by salivary glands, pancreas and small intestine.
          • Substrate- starch.
            • Product- glucose.
      • Amylase
        • Made by salivary glands, pancreas and small intestine.
          • Substrate- Carbohydrate
            • Product- sugar molecules
      • Protease
        • Made by stomach, pancreas and small intestine
          • Substrate- protien. Product- amnio acids
      • Lipase
        • Made by the pancreas and small intestine.
          • Substrate- Lipids. Product- Fatty acid and glycerol


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