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Transport in Plant What you would learn? •The transport structures of plants. •How substances move in plants. •How water enters the plants. •How water move against gravity. Vascular Tissues • A system of transport vessels in plants. • Composed of xylem and phloem. Transverse section of a typical Dicotyledonous plant stem. • Vascular tissues extends from the roots • through the stem • to the leaves. Xylem tissues • Long, hollow cylindrical tubes. • Dead -> little resistance to water flow. • Conducts water and dissolved mineral salts from roots to stem and leaves. Xylem tissues • Wall are lined with lignin. • Lignin -> tough and hard substance. • Deposited in spiral, ring, pit. • Provides mechanical support for the plants. Phloem tissue • Transport manufactured food (amino acid and sucrose) from the green parts to other parts of the plant. Translocation • Sieve tubes and companion cells. Sieve tube – Columns of elongated thin-walled living cells. – Degenerated protoplasm. – Cells separated by cross wall known as sieve plates. • Holes rapid flow of sugars through the tubes. Sieve plates Companion cells – Provides nutrients and help sieve tubes cells to transport food. – Numerous mitochondria to provide energy to load sugars from the mesophyll tissue into the sieve tubes. Energy needed -> Active transport Arrangement of vascular tissues in stems What do you notice about the arrangement of vascular tissues in the stem? Vascular Tissues in Stems. • Xylem and phloem grouped together to give vascular bundles. • Arranged in a ring around the pith. Epidermis (covered with cuticle) Cortex Phloem (near to the ‘outside’) Xylem Pith Vascular bundles Cambium divides and differentiates to form new xylem and phloem tissue Xylem Cambium Phloem Arrangement of vascular tissues in roots What do you notice about the arrangement of vascular tissues in the stem? vascular tissues in roots • Xylem and phloem alternate to each other. • Not grouped in bundles. Phloem Xylem Structure of roots Root hair Cuticle? Epidermis / piliferous layer Cortex Is this from root, stem or leaf? Is this from root, stem or leaf? • A– • B- Identify X & Y x y Studying the movement of water through a plant Studying of movement of sugars from leaves to other parts • Using aphids • Using carbon-14 isotopes. • Using ring experiment Ringing experiment Why is there swelling above the cut region? •Removing of bark would remove phloem. •Accumulation of food substances would cause swelling above the cut region. Pg 179 • Test Yourself