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Biology 2.5 (plant cell organisation (the leaf (epidermal tissue covered…
Biology 2.5
plant cell organisation
plants are made up of organs
organs work together to create organ systems
epidermal tissue - covers the whole plant
palisade mesophyll tissue - where most photosynthesis happens in the leave
spongy mesophyll tissue - big spaces to allow gasses to diffuse in and out in the leaf
xylem and phloem - transport minerals food and water around the plant
meristem tissue - found at the growing tips of shoots and roots able to differentiate
the leaf
epidermal tissue covered in a waxy cuticle to reduce water loss through evaporation
the upper epidermal is transparent to allow light to pass through
palisade has lots of chloroplasts
stomata are holes to let gasses in and out
stomata
guard cells are kidney shaped to allow gasses in and out of the stomata
when there is lots of water guard cells fill and go plump this causes the stomata to open
when there is a shortage of water the cells become flaccid and close
light sensitive - close at night
found mostly on the underneath
adapted for there purpose
transpiration effects
light intensity
brighter the light the greater the rate
temp.
the warmer the faster it happens
air flow
more air flow = more transpiration
humidity
the drier the air around it is the faster it goes
transpiration and translocation
phloem
made of columns of elongated living cells with small pores in the end walls to allow cell sap to flow through
transport food substances for immediate uses
transport in both direction
process called translocation
xylem
made of dead cells
hole down the middle
carry water and minerals from roots - leaves
transpiration
loss of water through evaporation
causes a slight shortage in water so more water is brought up the plant
more water is drawn up from the soil