bio ch 3 & 4

• Vascular plants


  Plants that have tissue for conducting water and minerals throughout the plant

  
• Non-vascular plants


  Plants that do not have a transport system and use osmosis and diffusion to move substances from cell to cell
• Non-vascular plants


  • Moss, green algae
• Vascular plants


  • Characterised by specialised tissues called xylem and phloem, enabling them to efficiently transport water and nutrients throughout their structures

  
• Plant systems


  • Above-ground shoot system
  • Below-ground root system
• Shoot system


  Site of photosynthetic organs/gas exchange, site of reproductive organs, transport of sugars, includes stems, leaves, flowers, fruit

  
• Root system


  Anchors plant in soil, absorption and conduction of water and minerals, storage of extra sugars as starch, includes roots, lateral roots, root hairs
• Plant tissues


  • Dermal
  • Ground
  • Vascular (Xylem and phloem)

  
• Meristematic tissue

  Can still divide
• Permanent tissue


  Can no longer divide
• Dermal tissue


  Protects plants and minimises water loss
• Ground tissue


  All tissues that are not dermal or vascular
• Vascular tissue


  Composed of xylem and phloem
• Xylem


  Tubes that transport water and minerals such as potassium, nitrogen and phosphorus in one direction from the roots to the leaves

  
• Xylem


  • Made up of dead cells joined end to end to create a tube, as the cells mature the nucleus and cytoplasm disintegrate leaving the cells hollow and dead, the cell wall becomes strengthened with woody LIGNIN deposits, the 2 types of cell that make up xylem are vessel elements and tracheids
• Phloem


  Tubes that transport sugars and other nutrients around a plant in both directions

  
• Phloem


  • Made of non-lignified living cells: sieve cells and companion cells, as sieve cells mature their nucleus and cytoplasm disintegrate so they are hollow but still alive, sieve plates are porous and located between each stacked sieve cell to allow flow, companion cells regulate the entry of nutrients into the phloem and perform functions to keep themselves and sieve cells alive
• Translocation


  The movement of nutrients from the leaves to other areas of the plant
• Water movement in plants

  1. Transpiration

  2. Capillary action (adhesion and cohesion)

  
• Root hairs


  Increase surface area to volume ratio to allow water and soluble nutrients to enter the roots via osmosis
• Stomata


  Leaf openings through which water exits the plant
• Transpiration


  The loss of water by diffusion through the leaf stomata, it is the pull of water required for photosynthesis and other processes, and allows nutrients into the leaf
• Water exits through stomata

  More water is dragged up from the roots through the plant
• Water evaporates from the leaf


  The air pressure in the leaf becomes lower than the pressure in the roots, creating a force that draws the water up through the xylem
• Capillary action


  Cohesion - water likes to stick to water, adhesion - water likes to stick to the sides of the xylem, the narrow xylem effectively draws water upwards

  
• Guard cells


  Regulate the opening and closing of stomata in response to water shortage
• Plants respond to water shortage

  They close their stomata to stop water loss through transpiration
• Closing stomata


  Stops photosynthesis as it also stops carbon dioxide and oxygen exchange