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biology 0610printed 98 · PDF 98
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printed 98 · PDF 98
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Notes
Plants take water and mineral ions from soil through roots. The water travels to leaves
for photosynthesis through xylem vessels. Mineral ions also travel through xylem
vessels
The sucrose and amino acids are transported to other parts of the plant by the leaves.
These substances travel through phloem tubes.
Xylem
Xylem is made up of a lot of hollow dead cells joined end to end. The end
walls of cells have also broken down making it a long continuous tube.
Xylem vessels do not contain nuclei or cytoplasm
This vessel runs from the root of plants right up the stem and then branches
out into every leaf.
The walls of xylem vessels are made up of cellulose and lignin.
Lignin is a very strong substance so it gives support to plants keeping it
upright.
Wood is entirely lignified xylem vessels.
Vascular Bundles
A group of xylem vessels and phloem tubes is called a vascular bundle.