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biology y9 revision - Coggle Diagram

- - - - Enzymes – Key Points:
      - Structure:
      - Enzymes are proteins with a special shape and an active site that fits specific molecules.
      - Function:
      - They speed up reactions like digestion (e.g. amylase breaks down starch).
      - Optimum Conditions:
      - Temperature: Best around 37°C (too hot = denatures).
      - pH: Each enzyme has a best pH (e.g. pepsin works in acid).
      - Substrate concentration: More = faster (up to a limit).
      - Human Heart
        
        Four chambers: 2 atria (top), 2 ventricles (bottom)
        
        Valves stop blood flowing backwards
        
        Left side pumps oxygenated blood to the body
        
        Right side pumps deoxygenated blood to the lungs
        
        Pumps blood around the body and to lungs
        
        Human Lungs
        
        Made of tiny air sacs called alveoli
        
        Surrounded by capillaries for blood flow
        
        Exchanges oxygen and carbon dioxide
        
        Lung Adaptations for Gas Exchange
        
        Large surface area (many alveoli)
        
        Thin walls (1 cell thick)
        
        Good blood supply (capillaries)
        
        Moist lining to dissolve gases
- - - - Made in: Liver
        
        Stored in: Gall bladder
        
        pH: Alkaline (basic), around pH 8
        
        Function:
        
        Neutralises stomach acid to create the right pH for enzymes in the small intestine
        
        Emulsifies fats, breaking them into smaller droplets to help lipase work better
        
        BILE:
      - The products of digestion (like glucose, amino acids, and fatty acids) are used by the body to build new carbohydrates, lipids, and proteins. Some of the glucose is also used in respiration to release energy.
      - Substance Test Name Reagent Used Positive Result
      - Starch Iodine test Iodine solution Turns blue-black
      - Glucose Benedict’s test Benedict’s solution Turns brick-red on heating
      - Protein Biuret test Biuret solution Turns purple
      - Fat Emulsion test Ethanol + water Milky white emulsion forms
- - - - Here are conditions that increase the rate of fat breakdown by lipase:
      - Presence of bile: Emulsifies fats, increasing surface area for lipase.
      - Optimum temperature: Around 37°C for human enzymes.
      - Optimum pH: Slightly alkaline (around pH 8), where lipase works best.
      - Higher substrate concentration: More fat available for lipase to break down (up to a point).