Biology - Plant tissue and cells

Biology - Plant tissue and cells

1. LEAF STRUCTURE

   • guard cells
     • close when too much H2O lost
     • upper surface
     • regulate the opening and closing of stomata
     • control transpiration
   • upper epidermis
     • before palisade cells
     • no chloroplast, let light through
   • palisade cells
     • chloroplast
       • photosynthesis occurs
   • lower epidermis
     • stomata
       • underside of leaf
       • allow intake of CO2 + release O2
       • open during day
   • stomata
     • underside
     • protected from sun
       • excessive light increase H20 loss

2. USES OF EACH PART OF PLANT

   • vacuole
     • contains cell sap, storage
   • cell wall
     • strengthen cell
   • root hair cell
     • big surface area, many thin hairs, close to xylem, short diffusion distance
   • pholem
     • transports dissolved sugar to rest of plant - immediate use/storage
       • translocation
   • xylem
     • movement of water from roots to rest of plant, transpiration stream
   • meristems
     • differentiate into other cells, capable of division/growth
   • chloroplast
     • contains chlorophyll, trap light in order to convert to sugar, photosynthesis occurs

3. TRANSPIRATION

   • increase in wind speed
     • increase in temp
       • increase in light intensity
         • more water used for photosynthesis, less lost
       • increase in evaporation/diffusion
     • takes water vapour away

4. CELL SPECIALISATION

   • specific functions
   • sperm cells
     • reproduction, long tail, streamlined head, lots of mitochondria, digestive enzyme
   • red blood cell
     • no nucleus, biconcave,small
   • nerve cell
     • extensions, sheath insulates. prevent loss of impulse/faster