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  • Created by: olivia
  • Created on: 22-09-17 17:39
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  • Biology-topic B4: Bioenergetics
    • rates of photosynthesis
      • factors = light, CO2, chlorophyll and Temperature
      • carbon dioxide + water __________               glucose + oxygen
      • takes place in chloroplasts in green plant cells
        • energy is transferred to chloroplasts from the environment by light
      • process is endothermic (energy transferred in from surroundings)
      • uses glucose for: respiration, making cellulose, making amino acids, stored as oils/fats, stored as starch.
      • amount of chlorophyll can depend on disease or environmental stress such as lack of nutrients.
      • not enough light or too little CO2 slows down the rate of reaction
    • Respiration and Metabolism
      • respiration = the process of transferring energy from glucose which goes on in every cell.
      • respiration is exothermic (energy transferred out to the environment)
      • metabolism = all the chemical reactions in an organism
      • lots of small glucose molecules join together to form starch and cellulose
      • glucose is combined with nitrate ions to make amino acids which are then made into proteins.
        • excess protein is broken down in a reaction to produce urea. urea is then excreted as urine
      • aerobic respiration needs plenty of oxygen
        • anaerobic respiration is used if there isn't enough oxygen (incomplete breakdown of glucose)
          • anaerobic respiration in yeast cells is called fermentation
        • most aerobic reactions occur in mitochondria
    • Exercise
      • when exercising you respire more
      • muscles need energy from respiration to contract.
      • increase in respiration means that muscles require more oxygen.
      • breathing rate and breath volume increases to intake oxygen
        • heart rate increases to carry oxygenated blood around the body faster.
      • long periods cause muscle fatigue.
      • carbon dioxide is removed quicker with faster respiration
      • vigorous exercise means that oxygen can't be supplied therefore the body respirates anaerobically.
      • anerobic respiration leads to oxygen debt
    • Inverse Square Law
      • links light intensity and distance
      • as distance increases, light intensity decreases
        • further away from lamp = dimmer light
        • light intensity decreases in proportion to distance
        • putting one over the distance shows the inverse
      • you can use 1/d squared as a measure of light intensity

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