1.5

Cards (17)

  • Cuticle
    • transparent - allows light through to lower layers containing chlorophyll
    • waxy and waterproof - reduces water loss
  • Palisade layers
    cells are packed with chloroplasts for photosynthesis
  • Phloem
    transports sugar away from leaf
  • Xylem
    brings water to leaf
  • Guard cells
    • open and close the stomata
    • allow carbon dioxide to enter
    • prevents water loss
  • Spongy layer
    • contains large air spaces - allows carbon dioxide to reach palisade cell for photosynthesis
    • cells here contain chloroplasts - for photosynthesis
  • Photosynthesis
    carbon dioxide + water --(light energy and chlorophyll)-> glucose + oxygen
  • Limiting factors
    • light intensity
    • carbon dioxide concentration
    • temperature
    • water
  • Light intensity
    • 1/distance²
    • rate of photosynthesis + light intensity increases
    • standstill occurs due to limiting factors such as temperature and carbon dioxide concentration
  • Carbon dioxide concentration
    • rate of photosynthesis + co2 concentration increases
    • standstill occurs due to limiting factors such as temperature and light intensity
  • Temperature
    • rate of photosynthesis + kinetic energy increases
    • reaches optimum temperature (around 20 °c )
    • enzyme denatures (around 25 °c)
  • Water
    • increasing it doesn't increase the rate of photosynthesis
    • too much will kill the plant by driving oxygen out of the soil - killing the roots of the plant
  • Phloem structure
    • two way flow of water and food - photosynthesis products
    • end walls with perforations
    • sucrose goes down to be glucose in the sink
    • glucose splits into starch which is insoluble and won't effect osmosis and controls the pressure produced
  • Xylem structure
    • One way flow of water and minerals
    • carries water uptake from root hairs in soil
    • water enters leaf and spongy mesophyll layer
    • water evaporates out of stomata - drawing more water up towards the leaf through the xylem vessel
    • cohesions (each other) and adhesion (walls)
    • walls of vessel are strengthened with lignin
  • Root hairs
    • water is in higher concentration (lower water concentration) in soil than in the root hair
    • mineral ions are pumped against concentration current, from low to high
    • process requires ATP energy - a product of aerobic respiration
  • KPN fertilisers
    ensures plants are taking in essential minerals
    • nitrate deficiency - poor plant growth
    • phosphate deficiency - poor root growth
    • potassium deficiency - yellowing of leaf
  • Structure of a leaf
    A - cuticle
    B - upper epidermis
    C - palisade layer
    D - phloem
    E - xylem
    F - lower epidermis
    G - guard cells
    H - stoma
    I - spongy layer