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B2 (Digestive system, Plant tissues organs and systems, Food test…

- - - - Found in the roots, stems and leaves
      - Made of dead cells joined together creating a continuous tube
      - Strengthened with lignin
      - Allows movement of water and mineral ions from the roots to the stem and leaves where it evaporates and leaves the plant (Transpiration)
      - Lignin is waterproof so water only leaves at specific places
    - - Elongated cells with holes in the cell walls
      - Food can be moved in both directions from either the leaves or roots from storage to wherei its needs (Translocation)
- - - - Carbohydrates include sugars and starches
      - Starch is a polymer of glucose
        
        Cellulose is also made of glucose and it makes up plant cell walls, so it makes up a part of our diet and cannot be digested so it is egested
      - Once absorbed into the body, glucose molecules are transported to cells and used for respiration or reassembled into the carbohydrate glycogen
    - - Proteins are made of amino acids
      - Proteins are big molecules that are too large to pass through the gut wall and therefore need to be converted into amino acids
        
        Once inside the body the amino acids are converted into the proteins that the individual needs in the process of protein synthesis and excess amino acids are broken down in the liver
    - - Lipids are esters of fatty acid and glycerol
      - Lipids cannot pass through the gut wall and must be digested first
      - In body's cells they are reassembled into the lipids the body needs e.g. cell membrane
  - - - Substrate collides with active site and becomes attached
        
        Active site has a complementary shape to the substrate
      - Enzyme catalyses breakdown the of the substance
        
        The fit between an enzyme and substrate is like a lock and key
      - Products are released from the active site
        
        Enzyme molecule is unchanged and can be reused
    - - Temperature
        
        Low temperatures - less collisions per second due to decreased kinetic energy so slow reaction
        
        High temperatures - can denature the active site which means the substrate cannot fit into the active site
      - pH
        
        Extreme pH differences can denature enzymes
    - - Carbohydrase break down carbohydrates
        
        The carbohydrase that breaks down starch is amalayse
        
        In the mouth and small intestine to break down into simple sugars and glucose
      - Protease breaks down proteins
        
        In the stomach and small intestine to break down into amino acids
      - Lipase breaks own lipids
        
        In the small intestine to break down into fatty acids and glycerol
- - - - Pulmonary vein - Left atrium - Left ventricle - Aorta
    - - Vena cava - Right atrium - Right ventricle - Pulmonary artery
  - - - Upon gas exchange, alveoli fill with oxygen and the capillaries flow with deoxygenated blood and the oxygen moves down the concentration gradient into the blood