transport tissues in plants
- Created by: Em99
- Created on: 27-04-16 21:20
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- Transport tissues in plants
- Xylem
- cellulose microfibrils vertically in the stem increase the strength.
- as the stem ages, increasing amounts of lignin are laid down in the walls
- cells become impermeable to water
- tissue becomes ore supportive + contents of the cell die
- the living cells around the cambium are on the outside of the tree under the bark
- end walls between cells break down so xylem forms hollow tubes running from roots to the tip of stems and leaves
- water and minerals are transported from roots to leaves in the transpiration stream
- water moves from xylem to surrounding cells through specialised pits in the walls
- Phloem
- phloem sieve tubes are made up of cells joined to make tubes that run from highest shoots to end of the roots
- walls between cells become perforated to from specialised sieve plates
- phloem contents flow through holes to these plates
- phloem sieve tubes survive because they have companion cells
- companion cells are very active linked to sieve tube elements by plasmodesmata
- cell membranes od companion cells have infolding's to increase surface area which they can transport sucrose to the cell cytoplasm
- Untitled
- Xylem
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