waxy cuticle = reduces water loss but allows light through for photosynthesis
upper epidermis:
secretes a waxy layer to reduce water loss
transparent to allow light to pass through
protective layer to prevent entry of pathogens
palisade : tall, thin cells packed closely together , specialised to contain lots of chloroplasts -> for maximum light absorption
tissue -> more effective
spongy layer = large air spaces allow gases to circulate in the leaf -> carbon dioxide can diffuse to the cells for photosynthesis + all cells ensured oxygen for respiration
lower epidermis = has stomata pores to allow carbon dioxide + oxygen into leaf -> guard cells can close stomata to reduce water loss
xylem ( water and minerals ) = brings water to the leaf -> needed for photosynthesis (thick cell walls to hold water)
phloem (sugars) = takes away some of the products of photosynthesis for other parts of the plant to utilise and for storage
plant has enough water -> guard cells open the stomata -> allow gas exchange
plant does not have enough water -> guard cells shrivel up and close the stomata -> reduces water loss
