Plant nutrition and transport (section 3) bio

• photosynthesis is the process by which plants convert light energy into chemical energy
• Photosynthesis produces glucose.
• photosynthesis happens in the leaves in the chloroplasts
• equation for photosynthesis 


  Carbon dioxide + water = glucose + oxygen
• photosynthesis converts light energy to chemical energy
• Structure of a leaf

  
• Chloroplasts are found in the palisade layer of the leaf. they get the most light
• upper epidermis is transparent so that light can pass through to the palisade layer
• Xylem transports water
• phloem transports nutrients such as sucrose and amino acids from the leaves to other parts of plant
• waxy cuticle reduce water loss by evaporation
• stomata lets co2 diffuse directly to the leaf
• limiting factor is something that stops photosynthesis from happening any faster
• limiting factors depend on environmental condition
• Test a leaf for starch

  • hold leaf by tweezer and dunk it in boiling water this stops chemical reactions happening in the leaf
  • now put the leaf in a boiling tube with some ethanol
  • heat it in water bath until it boils this gets rid of chlorophyll and makes the leaf white
  • rinse the leaf in cold water
  • add few drops of iodine solution
  • if starch is present the leaf will turn blue-black
• Plants absorb nutrients through roots via diffusion or active transport
• Root hair cells have lots of surface area so they can take up more nutrients
• Water moves into root hairs by osmosis because there are high levels of solutes inside the plant cell compared to outside.
• Transpiration is caused by the evaporation and diffusion of water from a plant’s surface. Most of transpiration happens in the leaf
• translocation

  the movement of food substances around the plants
• transpiration rate is affected by :


  light intensity: the brighter the light the greater the transpiration rate.

  tempreture : the warmer the faster transpiration happens

  wind speed : the higher the wind speed the greater the transpiration rate

  humidity : the drier the air, the faster transpiration happens
• Waxy cuticle helps reduce water loss by evaporation