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Answer:
Xylem is the specialised tissue of vascular plants that transports water and nutrients from the plant–soil interface to stems and leaves, and provides mechanical support and storage. ... The water‐conducting xylem cells provide an internal hydrophobic surface facilitating water transport as well as mechanical strength.
Answer:
Xylem is the specialised tissue of vascular plants that transports water and nutrients from the plant–soil interface to stems and leaves, and provides mechanical support and storage. The water‐conducting function of xylem is one of the major distinguishing features of vascular plants. Water is the primary solvent for plant nutrition and metabolism, and is essential for photosynthesis, turgor and for transport of minerals, hormones and other signalling molecules. The water‐conducting xylem cells provide an internal hydrophobic surface facilitating water transport as well as mechanical strength. The xylem cells also support the weight of the water transported upward in the plant and the weight of the plant itself. For many trees, xylem is wood, which has been an essential raw material for human societies since antiquity, providing structural material, fuel and fibre. Modification of xylem by genetic engineering may lead to better energy sources, improved raw materials and wood products.
Key Concepts:
Xylem is the tissue of vascular plants that transports water and nutrients from the soil to the stems and leaves.
Xylem plays an essential ‘supporting’ role providing strength to tissues and organs, to maintain plant architecture and resistance to bending.
The water‐transporting cells of mature xylem are dead, and therefore the transport of water is mostly a passive process with a very small active root pressure component.
In most woody plants, xylem grows by the division and differentiation of cells of a bifacial lateral meristem, the vascular cambium, which produces secondary xylem and phloem.
Xylem is wood, one of the world's most abundant and valuable renewable raw materials.
The morphology, frequency and distribution of xylem cell types determine its biological, physical and chemical properties, and the resulting properties of wood.
The chemical and physical properties of wood determine its role in the carbon cycle through its carbon storing capacity and its resistance to decay when alive or dead, and in various sediments.
The chemical and physical properties of wood are themselves determined by the composition and interactions of the three polymers, cellulose, hemicellulose and lignin.
The difference between a woody and herbaceous plant depends on the expression of a small number of regulatory genes controlling the duration and quantity of xylem formation.
Genetic engineering has great potential to develop xylem with desired qualities for specific purposes.