pt 1

• why do plants require water

  photosynthesis

  maintenance of structure

  cooling effect
• why do plants require mineral ions

  for growth , e.g nitrates are required to produce proteins
• what structure in the plant is adapted for the uptake of water and minerals

  root hairs
• how is water transported into root hairs

  lower concentration of water in root hair cells than in the soil

  water then enters the root hair cells via osmosis down the concentration gradient
• how are minerals transported into root hairs

  root hair cells take up mineral ions by active transport as there is a lower concentration of mineral ions in the soil than in the root
• how are root hair cells adapted for the absorption of wtaer and minerals

  plant roots are composed of millions of root hair cells which have

  long hairs that extend from their body , increasing the surface area for absorption

  lots of mitochondria so that enough energy is released for active transport of mineral ions
• name two plant transport tissues

  xylem

  phloem
• what is the function of the xylem 


  transports minerals and water up the plant from the roots to the leaves via the transpiration stream
• how is the xylem adapted to its function

  thick cell wall strengthened with lignin to provide support

  no end walls which provides little resistance to the passage of water

  composed of dead cells laid from end to end to form a long continuous column
• what is the function of the phloem

  transport food substances(mainly sucrose) made in the leaves to the rest of the plant for immediate use or for storage via translocation
• what are the 2 cell types that make up the phloem

  sieve tube cells

  companion cells
• how is the phloem adapted to its function

  sieve tube elements are long thin cells , laid end to end with perforated plates to enable the flow of sugars , they contain no nucleus and little cytoplasm to allow sugars to flow easily ,

  companion cells(adjacent to sieve tube elements) contain a dense cytoplasm , nucleus and mitochondria , they provide energy to the processes in the phloem when its needed
• what is transpiration

  the loss of water vapour from the parts of a plant exposed to the air due to evaporation and diffusion
• where does the majority of transpiration take place

  leaves
• describe the process of transpiration

  water evaporates from the plant and some is also diffused from the stomata , this causes a slight shortage of water in the plant , therefore more water molecules are drawn up from the rest of the plant via the xylem tissue so that the evaporated water can be replaced , this causes more water from the soil to be absorbed by the root hair cells