Xylem transport nitrates, phosphates, water and other mineral salts from the roots to other parts of the plants, like the leafs, flowers and buds.
Xylem consists of columns of hollow, dead cells. Substances are carried up the tube dissolved in water.
You can add this link to 2.52 as a sum up video :
ReplyDeletehttp://www.youtube.com/watch?v=ASW-ojhEva4&list=PL79CE52307F114FAB
How are they carried up the tube?
ReplyDeleteTranspiration?
DeleteBy transpiration stream :-) Phloem uses translocation.
DeleteThe loss of water from mesophyll cells, during transpiration, causes water to be drawn from surrounding cells. This means that water is 'pulled up' the stem, from the roots, in a continuous flow called the 'transpiration stream'. Hope this helps!
ReplyDeleteWater is taken in through the root hair cells from the soil by osmosis, as there is a greater water potential in the soil. The water then enters the xylem vessel through the cotex cells, or just goes through the cells of the xylem vessel. The water is then drawn up the xylem by diffusion, as there is concentration differences, due to water transpiring further up the plant. The transpiring water also creates a lower pressure to the top of the plant,further causing the water to be drawn up the xylem. The water then enters the spongy mesophyll layer of the plant.
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