Plant structures and their functions

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  • Section 6 - Plant structures and their functions
    • Photosynthesis
      • Plants use energy from the sun to produce glucose which helps grow more complex structures and adds to the biomass of the plant.
      • Occurs within the chloroplasts
      • Endothermic reaction
    • Limiting factors in photosynthesis
      • Not enough light slows down the rate
        • rate is directly proportional to light intensity until a certain point where temperature or carbon dioxide is the limiting factor
      • Too little Carbon Dioxide also slows it down
        • If there is enough light and Carbon Dioxide then temperature must be the limiting factor
      • Temperature has to be just right
        • Enzymes work too slowly at lower temperatures
        • If the temperature is too high the enzymes denature
    • Transport in plants
      • Root hairs take in minerals and water
        • Each branch of roots is covered with millions of microscopic hairs
          • Increased surface area for absorbing minerals from the soil
        • Mineral ions are absorbed by active transport and water is absorbed by osmosis
      • Pholem tubes transport food
        • translocation process requires energy from respiration and goes both ways
      • Xylem tubes take water up
        • transpiration stream,through tubes of dead cells joined end to end
      • Transpiration is the loss of water from the plant
        • Constant transpiration through the plant
        • Caused by the diffusion and evaporation of water from a plant's surface
    • Stomata and transpiration
      • Stomata are needed for gas exchange
        • Tiny pores on the surface of plants that allow gas exchange
        • Guard cells change shape to control the size of the pore
      • Transpiration rate is affected by environmental factors
        • Brighter light increases transpiration rate, stomata begin to close as it gets darker
          • Light intensity
        • Warmer temperatures increases rate
          • Temperature
        • In stronger winds the diffusion process is quicker
          • Air flow
      • You can estimate a transpiration rate
        • Use a potometer


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