transport in plants

• epidermis

  covers outside surfaces of plant for protection
• palisade mesophyll

  main site of photosynthesis in the leaf
• spongy mesophyll

  air spaces between the cells allow gases to diffuse through the leaf
• xylem vessels

  transports water and minerals through the plant, from the roots to the leaves. Also supports the plant
• phloem vessels

  transports dissolved food materials through the plant
• meristem tissue

  found mainly at the tips of roots and shoots, where it can produce new cells for growth
• why are many chloroplasts close to the top of the leaf?

  to trap maximum sunlight
• why are there so many air spaces?

  to allow gasses to diffuse
• what does the stomata do?

  allows the diffusion of gases in and out of the leaf. can be opened by guard cell
• what is transpiration?

  when the water diffuses out of the stomata after the water and minerals are carried to the leaves by the xylem vessels
• factors which affect rate of transpiration :

  temperature, light intensity, humidity, fast wind
• why are the stomata closed at night?

  carbon dioxide is not needed for photosynthesis, so closing reduces water loss
• how can the rate of transpiration from a cut shoot be estimated?

  measuring the rate at which the shoot takes up water
• what is translocation?

  transport of dissolved sugars around the plant in the phloem
• what happens when water is plenty?

  guard cells take up water and bend. this causes stomata to open, so gases for photosynthesis are able to move in and out of the stomata along with water from transpiration