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    GCSE Class Questions - due by Thursday!


    • "What does Starch Testing tell you about Chlorophyll and Photosynthesis?"
    • "Why do plants store energy in the form of starch rather than glucose?" - need links to solubility and concentration gradients.
    • "How do enzymes help digestion?"
    • "What is the link between bile and lipase?"


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    "What does Starch Testing tell you about Chlorophyll and Photosynthesis?"

    Starch is made of glucose, and acts as an energy storage for the plant. Chlorophyll is required in photosynthesis whose product is glucose. The amount of starch present in a plant is therefore correlated with its photosynthetic activity. The more photosynthesis takes place, the more glucose is produced, which then adds to the starch reserves.

    "Why do plants store energy in the form of starch rather than glucose?" - need links to solubility and concentration gradients.

    Glucose is soluble, starch is not. This means glucose uses up water to surround itself (hence is soluble) while starch does not interact with surrounding water at all. This means that glucose present alters water potential in a cell, while starch does not. If energy were stored simply as glucose rather than starch, the water potential in cells would quickly decrease, resulting in water flooding into the cell.

    "How do enzymes help digestion?"

    Digestion is the physical and chemical breakdown of larger molecules into smaller ones, releasing energy. Enzymes are the catalysts of the body, speeding up reactions that would otherwise take a very long time. In digestion, enzymes catalyse the breakdown reaction of a bigger molecule such as lactose into its constituent sugars, glucose and galactose. This reaction is hydrolysis and involves water.

    "What is the link between bile and lipase?"

    Bile is released to help digest fats (lipids). Lipase is the enzyme that helps carry out this reaction. So, bile contains lipase.
 
 
 
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