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Transport in Plants
L/O to be able to describe, with the aid of diagrams andphotographs, the distribution of xylem andphloem tissue in roots, stems and leaves of
dicotyledonous plants;
Plant
Stem
Role of the stem
• Support – hold leaves in place for sunlight• Support – hold flowers in place for pollination• Movement of materials from leaves to other
parts• Movement of water in stream from the roots
to leaves. Also move ions.• Are green and carry out a small amount of
photosynthesis
The Three Tissue Systems
Dermal Tissue – plant’s protective covering in contact with the environment
Vascular tissue – this tissue conducts water and solvents between organs and provides mechanical support
Ground tissue – packing and supportive tissue accounts for much of the bulk of the young plant
Cross section of a stem
Vascular Tissue• Xylem and phloem conducting elements are associated with parenchyma
cells• Phloem – transports organic solutes (sucrose) in the plant• Have lost their nuclei and much of their cytoplasm• Actively transport soluble food products into and out of sieve tube
elements
Vascular Tissue - Xylem
• Carries water and dissolved ions in the plant• Dead cells at maturity that lack a plasma
membrane• Cell wall has been secondarily thickened and
lignified (lignified tissue called metaxylem)• Enables very long continuous tubes to be
formed
Vascular bundle...
Notes pgs 68-69...• Give the functions of xylem, phloem,
meristem, cambium, vascular bundle
xylem
phloem
Definitions• Cambium - A cellular plant tissue from which phloem, xylem, or
cork grows by division, resulting (in woody plants) in secondary thickening
• Vascular Bundle - A strand of conducting vessels (transport tissue) in the stem or leaves of a plant, typically with phloem on the outside and xylem on the inside.
• Meristem - A region of plant tissue consisting of actively dividing cells forming new tissue
• Phloem - The vascular tissue in plants that conducts sugars and other metabolic products upward and downward between the leaves and root.
• Xylem - The vascular tissue in plants that conducts water and dissolved nutrients upward from the root and also helps to form the woody element in the stem
Summary...
• The vascular tissue in a leaf forms a network of bundles that finally merge to form one central (1) which runs into the stalk of the leaf that is also called the (2). The vascular tissue found nearest to the upper surface of the leaf is (3). In stems, the vascular tissue nearest the outside of the stem is (4). Inside this tissue is a layer of dividing tissue called (5) and outside it there is often a region of supporting tissue called (6). The vascular tissue in stems forms a cylinder towards the outer edge as this arrangement best resists the (7) forces that stems are subjected to. In roots, the vascular tissue is central in order to resist the (8) forces experienced by the roots.
Missing words…
1. Vein2. Midrib3. Xylem4. Phloem5. Cambium (meristem)6. Parenchyma7. Shearing/bending8. Pulling