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Amelia Kirk

Transport in Plants Summary

Need of a transport system
every cell of multicellular plants needs regular supply of water & nutrients
epithelial cells can use simple diffusion, but cells not exposed to external environment within
the plant cannot
plants can obtain water from the roots, but not sugars,…

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so water column does not break easily & allows capillary action to work better, pits in lignified
wall allow water to move between xylem vessels, lignin is deposited in spiral, annular or
reticulate patterns to allow flexibility as plant grows
phloem tissues : made of sieve tube elements & companion…

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transpiration: loss of water through the leaves in plants as a result of gaseous exchange (the
stomata are open allowing water vapour to leave the plant), water leaves xylem & moves in
mesophyll cells (via osmosis), water evaporates from surface of mesophyll cells forming water
vapour which then passes…

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Reducing water loss:
plants need to take in carbon dioxide for photosynthesis & remove oxygen (a waste product)
so stomata must be on during the day allowing water loss
to reduce water loss plants have certain adaptations: waxy cuticle on top leaf, stomata on
underside of leaf, stomata close at…

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reduces sugar concentration in the cells so sucrose molecules move by diffusion/active
transport from sieve tube element to surrounding cells increasing the water potential in sieve
tube element so water molecules move into surrounding cells by osmosis reducing
hydrostatic pressure
Along phloem:
water entering phloem at source, leaving at sink,…


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