Plant Nutrition

• Cuticle on leaves


  Waxy to prevent water vapour diffusing out of the leaf through the epidermis. Also, prevents pathogens from entering.
• Upper epidermis


  • It is transparent. This allows light to pass through to the cells below for photosynthesis.
• Leaves


  • Flat and thin to give them a larger surface area to volume ratio so they can absorb a lot of light energy
  • Also means that the distance light and gases have to travel to get to cells for photosynthesis is shorter
• Air spaces


  Found in the spongy mesophyll layer
• Nitrate ions


  Needed to make amino acids and to build protein
• Plant with nitrate ion deficiency
• Magnesium ions


  To make chlorophyll required for photosynthesis
• Plant with magnesium ion deficiency
• Phosphate ions


  Needed for respiration to help plant cells release energy
• Plant with phosphate ion deficiency
• As temperature increases


  The rate of photosynthesis increases
• Photosynthesis is a series of enzyme-controlled reactions
• Enzymes get too hot around 45°C
• Xylem


  Vessel that carries water and minerals around the plant
• Phloem


  Vessel that carries sugar (sucrose) around the plant
• Root hair cell


  Cell found in the roots of a plant where water enters
• Water entering root hair cells

  By osmosis
• Mineral ions entering root hair cells

  By active transport
• Root hair cells


  • Give the cell a larger surface area to volume ratio to increase the rate of water and mineral uptake
• Chloroplast


  Where photosynthesis takes place in a plant cell
• Chlorophyll


  Green pigment found inside the chloroplast that absorbs light energy for photosynthesis
• Palisade mesophyll layer


  Cells containing the most chloroplasts, located at the top of the leaf where it receives the most light
• Stomata


  Tiny holes on the bottom of the leaf where gases can enter and exit
• Guard cells


  Cells around the stomata that determine whether it is open or closed
• Factors affecting photosynthesis


  • Light intensity
  • Concentration of CO2
  • Temperature
• Pond weed/Elodea


  Plant that can be used to measure the rate of photosynthesis
• Calculating light intensity


  Inverse square law
• Light intensity increasing


  Rate of photosynthesis increases up to a point, then it becomes no longer the limiting factor
• CO2 concentration increasing


  Rate of photosynthesis increases up to a point, then it becomes no longer the limiting factor
• Before carrying out a photosynthesis experiment

  De-starch a plant by leaving it in the dark for 48 hours
• Proving chlorophyll is needed for photosynthesis


  Use a variegated leaf, place in sunlight, then test for starch
• Proving light is needed for photosynthesis


  Cover part of a de-starched leaf, place in light, then test for starch
• Proving CO2 is needed for photosynthesis


  Place a de-starched plant in a sealed bag with potassium hydroxide, then test for starch
• Photosynthetic organism


  An organism that does photosynthesis, e.g. plants or algae
• Biomass


  The mass of living material
• Producers


  Organisms that make their own food
• Photosynthesis is endothermic
• Word equation for photosynthesis

  Carbon dioxide + Water -> Glucose + Oxygen
• Symbol equation for photosynthesis

  6CO2 + 6H2O -> C6H12O6 + 6O2
• Stages of photosynthesis


  2 stages