Phloem
- Created by: Harriet Goodship
- Created on: 07-01-13 21:17
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- Phloem
- Function
- Transport sugars from one part of the plant to another, up or down the stem
- Phloem Components
- Sieve Tube Elements
- Contain little cytoplasm and no nucleus
- Lined up end-to-end to form a tube where sugars can be transported
- Typically sucrose
- Sucrose is dissolved in water to form sap
- Unlike xylem, this tube contains cross-walls at intervals
- These cross walls are perforated by pores to allow the sap to flow
- Hence cross walls are called sieve plates and tubes are called sieve tubes
- Sieve tubes have thin walls and are normally 5 or 6 sided
- Hence cross walls are called sieve plates and tubes are called sieve tubes
- These cross walls are perforated by pores to allow the sap to flow
- Typically sucrose
- Companion Cells
- In between sieve tubes with large nucleus' and dense cytoplasm
- Have numerous mitochondria to produce ATP in active transport
- Active transport used to load sucrose into sieve tubes
- Cytoplasm and sieve tube elements are linked through many plasmodesmata (gaps in cell walls allowing communication and flow of substances between cells)
- Sieve Tube Elements
- Function
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