transport systems - plants

• Transpiration is the movement of water throughout the plant. Water evaporates from the stomata in the leaf, this causes pressure changes within the plant meaning more water is drawn through the plant from the roots back into the leaves.
• • Waxy Cuticle – Prevents water loss
• • Upper epidermis – transperent to light to pass through and prevents water loss.
• • Palisade mesophyll - Main cells involved in photosynthesis, contains lots of chloroplasts
• • Spongy mesophyll - Contain air spaces to allow gas exchange, photosynthesise also occurs here
• • Guard cells - control the opening and closing of stomata, as this requires energy they also have chloroplasts
• • Stomata - Air spaces that allows oxygen and water to leave and carbon dioxide to enter the leaf.
• leaves can have a large surface area t maximise light absorption
• leaves are very thin to allow carbon dioxide to easily diffuse into cells
• vascular bundle - contains xylem and pholem
• parts of a leaf

  A) upper epidermis

  B) palisade mesophyll

  C) vascular bundle

  D) guard cells

  E) stomata

  F) guard cells

  G) waxy cuticle

  H) spongy mesophyll

  I) air space

  J) waxy cuticle

  K) lower epidermis

  
• rate of transpiration increases with faster wind speeds
• rate of transpiration decreases with slower wind speeds
• rate of transpiration is slower in more humid environments
• rate of transpiraton is faster in less humid environments
• transpiration is faster at higher temperatures
• transpiration is slower at lower temperatures
• rate of transpiration increases with higher surface area
• Xylem is a tissue consisting of dead, hollowed-out cells that form a system of pipes, The walls of xylem cells are strengthened with lignin, This allows the xylem to withstand pressure changes as water moves through the plant. water always moves upwards through the xylem.
• the pholem is the tissue in plants that transports the products of photosynthesis, including sugars and amino acids.
• The sugar produced in photosynthesis needs to be transported both up and down the plant to areas of new growth (root and shoot tips). so the pholem is made of living cells.
• Companion cells provide the energy for the sieve cells. The end walls of the sieve cells have pores through which sugar is transported from cell to cell.
• phoelem structure

  A) end wall

  B) companion cell

  C) sieve tube