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| Frage | Antworten |
| What is the role of xylem tissue? | Xylem tissue transports water and minerals in solution |
| What is the role of phloem tissue? | Phloem tissue transports sugars both up and down the plant |
| Describe the distribution of xylem and phloem tissue in the roots, stem and leaf |
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| Describe the structure of xylem vessels | Long, tube-like structures formed from vessel elements joined end-to-end An uninterrupted tube Cells are dead so they contain no cytoplasm Cell walls are thickened with lignin (helps to support walls and prevents collapsing inwards) Water and mineral ions move in and out through small pits |
| The cell walls of xylem vessels are thickened with lignin. Why? | Lignin helps to support the walls and prevents the cell from collapsing inwards |
| TRUE OR FALSE: The amount of lignin in xylem vessels increases as the cell gets older | TRUE |
| Describe the structure of phloem vessels | Tissue contains phloem fibres, parenchyma, sieve tube elements and companion cells Sieve tube elements are joined end-to-end Companion cells have no nucleus |
| What are the properties of sieve tube elements? | No nucleus Very thin layer of cytoplasm Few organelles Connected through holes in the sieve plates |
| What is the role of companion cells? | Companion cells carry out the living functions for both themselves and their sieve cells. E.g. they provide energy for active transport of solutes |
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