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IGCSE BIOLOGY------>TRANSPORT IN PLANTS

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Sue T:
Whoever asked the xylem thingi question im gonna xplain in my own words
Imagine sipping juice through a straw. The straw is really thin so the water rises through it easily-imagine sippin the juice through a pipe. Its hard ryt? So that’s pretty much capillary action, which is weak - u see xylem vessels r thin so water rises up against gravity easily.
Now in the root cells, thers pressure due 2 accumulation of water. This forces water out of one cell and into the other so they reach the xylem vessels. That’s root pressure or turger pressure but its also a weak pressure. Now @ th top, in the leaves, water is being lost due 2 transpiration. They are fewer water particles up here and more down the xylem vessels so as u no in osmosis water particles move from a region of high water potential to lower water potential n the water potential gradient is created due 2 all these thingis.Voila!water moves up :p
Hope u understand :D
n By the way i dunno tht hydrogen ions thingi cn u xplain more pls?

Wahab09:
Sure :)
Whats water?
H2O right?
The hydrogens are bonded with the oxygen. So the hydrogen ions in the H2O will move up (as it is lighter than the O2) so it will automatically drag the oxygen with it.
I dno if that makes any sense to you :P
But thats the way.
Here it is in definition terms:
Transpiration creates a pulling force which pulls a continuous unbroken column of water up the xylem vessels. The water molecules are held together by forces of attraction. This creates a water potential gradient through the plant.

 ;)

SGVaibhav:
i understood capillary action.

sweetsh
page 10
explain the mechanism of water uptake and
movement in terms of transpiration producing a
tension ('pull') from above, creating a water
potential gradient in the xylem, drawing
cohesive water molecules up the plant.

hmm
can anyone explain me cohesion and adhesion, and wat is pits in xylem

it would be good if someone has a summary of the whole topic.

Wahab09:
sgvaibhav
Non of the terms you mentioned you need to know for the Cambridge IGCSE exam this June. Trust me you just need to know how and stuff and i think Sue T and I have explained it clearly.

sweetsh:
Yes exactly as Wahab said....Those terms are not included...

But you should know how the water moves along the plant from the roots till leaving the leaf by the affect of transpiration....

I will explain you whats meant by pits and everything about the xylem vessels after 3 hours if you can wait =)

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