xylem

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lohita
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xylem

Post by lohita » Thu May 19, 2005 10:12 pm

What is the function of xylem tissue other than transportation??

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Post by ERS » Thu May 19, 2005 10:55 pm

structure and support
secondary xylem = wood in dicot plants

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Post by angela » Thu May 19, 2005 11:00 pm

try looking in the dictionary in the upper right hand side

good luck :)

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Xylem

Post by victor » Fri May 20, 2005 1:51 pm

Xylem is used for transport water and other minerals from the root to the leaves for photosynthesis.

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Post by MrMistery » Fri May 20, 2005 7:08 pm

Primary xylem tissue: transporting mater+minerals to the leaves
Suporting the plant(that is why xylem is on the inside)
Secondary xylem tissue(where it exists): only support of the plant
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Post by lohita » Sat May 21, 2005 12:12 am

then...is the woody part of a tree xylem tissue? :?

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Post by MrMistery » Sat May 21, 2005 9:51 am

Yes it is
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Post by Tamsicle » Sat May 21, 2005 1:47 pm

I might be wrong, but isn't the woody part of a tree lignin or something? Aren't there phloem as well? And there's those lateral things...what are they..? ...dammit. I don't remember the word. But if you were to saw a tree, and you'd see a star shape- it's those lateral vessels...I know xylem is composed of non living tissue, but there are those other vessels which are supposedly liviing (I think they have a cytoplasm but no nucleus?)...and how can a cell live without a nucleus? It seems ridiculous to me that they can be classified as living without a nucleus...they lose their nucleus? And how long can they survive for without one?

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Post by MrMistery » Sat May 21, 2005 6:30 pm

I'm guessing you are talking abot the phloem cells. It is true that they do not have a nucleus. Remember that plant cells comunicate with each other through plasmodesms. In this case the proteins those cells need are delivered by the anex cells through plasmodesms
Hope this helps,
Andrew
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Post by caite » Sat Jun 25, 2005 7:22 pm

In order for transpiration to take place H2O must be transferred from the roots to the stem an d then to the leaves where the guard cells while open. In order for this to happen xylem must be there to take the water up! I dont think it has any other purpose. But it will naturally cause the stem to stand up straight and not limp, if water is being sucked up! :) The xylem is completely different from the phloem, the phloem takes the food (nutrients) down to the roots, xylem carries only Water! And the phloem are not cells, their extremely thin tubes, like xylem. I believe that the xylem is smaller in width than the phloem!

I think but, im not sure, if your in high school/university, i suggest you ask a biology teacher!!!!

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Post by James » Sat Jun 25, 2005 10:48 pm

The seive cells have few organelles only to create more space, but aided by companion cells for living processes. Thats in the phloem, not xylem

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Post by MrMistery » Sun Jun 26, 2005 7:25 pm

The xylem does not carry only water, it carries mineral ions and about 1% organic substances. If you check any serious botany book, even a high-school textbook you will see that the xylem's secondary function is supporting the plant.
The phloem carries a solution of mostly organic substances, very few mineral ions. It cointains of 75% water and 25% organic substances. Out of this quarter, 90% is sucrose.
Both the xylem and phloem tissues are made of cells, the xylem's cells are dead and since they lose their transversal walls, they lose their individuality. The phloem's cells are alive, but they lose their nucleus and most organneles due to the high degree of specialisation and,as a consequence can not survive without the companion cells. Do not be confused by this however, they are still cells. It is true that they have the shape of thin tubes(both the xylem and phloem). Another thing worth telling is that the trasversal wall does not dissapear in the case of the phloem like in xyles, it just has holes in it
Hope this helps...
Andrew

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