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Water Transport in Plants

(pages 331 – 340). Water Transport in Plants. Sometimes water has a long, long way to go…. In multicellular organisms water must be transported over long distances. Some trees can transport water over 100 m from the root tips to the highest leaves. Xylem and Phloem Vessels.

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Water Transport in Plants

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  1. (pages 331 – 340) Water Transport in Plants

  2. Sometimes water has a long, long way to go… • In multicellular organisms water must be transported over long distances. • Some trees can transport water over 100 m from the root tips to the highest leaves.

  3. Xylem and Phloem Vessels • Vascular plants have a system of vessels that transport water, minerals, and sugars throughout the plant. • These vessels are like the blood vessels in your body. • Xylem and phloem are the specialized tissues that make up this transport system

  4. Xylem • Recall that the xylem tissue transports water and dissolved minerals from the roots to the leaves. • Xylem vessels are hollow tubes consisting of only cell walls. • At one point xylem tissues are living, in mature plants the xylem tissue is dead.

  5. Xylem con’t • The hollow tubes are linked end to end, forming long continuous tubes called xylem vessels. • Xylem vessels extend from near the tips of the roots up into the rest of the plant. • Without water transport the plant would die! (no photosynthesis)

  6. Phloem • Recall that the phloem tissues are responsible for transporting glucose (the product of photosynthesis) throughout the plant. • Phloem is composed of cylindrical cells joined end to end to form phloem vessels. • Phloem is composed of living cells and have porous walls to exchange materials with neighbouring cells.

  7. Phloem con’t Sugary sap flows down the phloem vessels from the leaves (where it is produced) to the roots (where it is stored)

  8. Vascular Bundles Xylem and Phloem are group together in bundles. These are called vascular bundles.

  9. Water Uptake in Roots • Water and minerals enter the plant from the roots. • A the core of the root are vascular bundles with xylem and phloem. • Epidermal cells cover the roots and are very permeable to water. • Water enters the cells of the epidermis by osmosis.

  10. Water Uptake in Roots • Root hairs increase the surface area of the roots for absorbing water and minerals. • Each root hair is an outgrowth of a single epidermal cell. • Water continues diffusing through epidermal cells until it reaches the xylem vessels.

  11. Water Uptake in Roots • The water and minerals that collects in the root xylem is called xylem sap • The xylem sap moves upward from the roots , through the stem and into the leaves. • The vessels branch into many veins once in the leaf.

  12. Mineral Uptake in Roots • Roots must use active transport to absorb minerals out of the soil and into the root. • The minerals have a lower concentration in the soil than in the plant. • The root must move the minerals against their concentration gradient Soil Root

  13. Water Uptake in Roots water transport in plants

  14. Properties of Water • Water is cohesive; molecules of water tend to stick together. • Water is adhesive; molecules of water tend to stick to other surfaces. • Cohesion and adhesion allow a column of water in a xylem vessels to move against the pull of gravity.

  15. Root Pressure • The turgor pressure inside the root xylem pushes a column of water upwards. • This is called root pressure. • As the root actively transports minerals into the root, water follows by osmosis. • This increases the root pressure, forcing the xylem sap upwards.

  16. Root Pressure, Cohesion and Adhesion Root pressure pushes; cohesion keeps the molecules moving together. Adhesion prevents the column of water from falling back down. transpiration

  17. Sugar Transport in Phloem • After water and minerals have been transported to the leaves the plant is ready for photosynthesis. • Glucose produced during photosynthesis must be transported for use in other areas of the plant.

  18. Sugar Transport in Phloem • As the sugar concentration increases within the phloem cells, water follows by osmosis. • The cells swell with an increase in turgor pressure. • The phloem sap (sugar, nutrient, and water mixture) flows down the concentration gradient and into the roots.

  19. Summary of Gas and Fluid Transport in Plants:label the movement of oxygen, water, carbon dioxide, sugar, and minerals

  20. Homework • Check Your Understanding page 340 • # 1 – 7, omit #4 • Study for “gas and water transport” quiz tomorrow

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