Transport in plants
- Created by: katie
- Created on: 24-03-13 12:41
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- Transport in plants
- Xylem transports water and mineral salts from the roots to leaves
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Phloem transports the soluble products-sucrose, sugars, organic molecules, amino acids
- source to sink of photosynthesis from leaves to other parts of the plant
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Xylem is made of vessels and tracheids
- Their secondary wall is lignified to waterproof and strengthen and support them to stop them collapsing under tension
- Xylem vessels form continuous tubes to carry water throughout the plant
- Mature Xylem vessels are dead and cytoplasm has gone so there is nothing to impede flow
- Tracheids have tapered ends that fit together and pits to allow transfer of water between cells
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Phloem is made of sieve tubes and companion cells
- Sieve tube cells lose most of their organelles and are still alive when mature
- Sieve tube cells have perforated sieve/end plates that allow solutes/sugar to pass through
- Sugar solution flows in both directions
- Cytoplasmic streaming
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Companion cells have all the organelles and communicate by plasmodesmata
- theyare responsible for keeping sieve tube cells alive/provide ATP
- Cohesion-tension, capillarity, adhesion in xylem of water molecules
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