transport in plants

• what is the function of the epidermis?

  covers the outer surfaces of the plant for protection
• what is the function of the palisade mesophyll?

  the main site off photosynthesis in the leaf
• what is the function of the spongy mesophyll?

  air spaces between the cells allow gases to diffuse through the leaf
• what is the function of the xylem vessels?

  transports water and mineral ions through the plant from roots to leaves and supports the plant
• what is the function of the phloem vessels?

  transports dissolved food materials through the plant
• what is the function of the meristem tissue?

  found mainly at the tips of the roots and shoots where it can produce new cells for growth
• structure of a leaf

  A) waxy cuticle

  B) upper epidermis

  C) palisade mesophyll

  D) air space

  E) spongy mesophyll

  F) stomata

  G) lower epidermis

  H) waxy cuticle

  I) guard cells

  
• water enters the plant from the soil through the root hair cells and is absorbed into the xylem by osmosis
• at the leaves, most of the water will evaporate and diffuse out of the stomata into the air
• what is transpiration?

  the loss of water through the leaves
• what 4 factors affect the rate of transpiration?

  • increased temperature (more energy is transferred.to the water to allow it to evaporate)
  • faster air flow (blows away water vapour allowing more to evaporate)
  • increased light intensity (causes the stomata to open)
  • increased humidity (decreases the rate, as air contains more water vapour so the concentration gradient for diffusion is lower)
• guard cells open and close the stomata
• why are the stomata closed at night?

  as co2 isn't needed for photosynthesis so closing them reduces water loss
• what is translocation?

  the movement of dissolved sugars through the phloem
• what does a potometer measure?

  Water uptake or transpiration rate in plants.