The Vascular System

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The Vascular System

• What two types of tissues make up the vascular
  system in plants?
• Xylem and Phloem

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What is xylem?

• Water and dissolved minerals move up from the
  roots to the rest of the plant through xylem.
• What are the two types of cells that make up
  xylem?
• Tracheid cells and vessel elements.

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Tracheid Cells and Vessel Elements

• Tracheid Cells
• Long and narrow.
• Water flows from cell to cell through openings in
  the thick cell walls.
• Vessel Elements
• Shorter and wider than tracheids.
• Both cells must die before water moves through
  them.

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How do plants move water through xylem?

• Cohesion-tension theory proposes that the
  physical properties of water allow the rise of
  water through the plant.
• What does this mean?
• Cohesion attraction btw molecules of the same
  substance.
• Adhesion attraction btw molecules of different
  substances.

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For Example.....
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Give an example cohesion and an example of
adhesion.
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So Back to the Cohesion-Tension Theory

• Simply put..... cohesion and adhesion create
  tension that moves water upward in xylem.
• There is one more force that drives the movement
  of water in plants..... transpiration

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Plant Sweat

• Transpiration is how plants sweat.
• Release of vapor through the pores of the skin or
  stomata of plant tissue.
• What role does evaporation play?

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Phloem

• Phloem carries sugars from photosynthesis
  throughout the plant,
• Phloem tissue is alive.
• Made of cells called sieve tube elements.

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Sieve Tube Elements

• Get their name from small holes in the end walls
  of their cells.
• As they grow these cells lose their nuclei and
  ribosomes.

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How does food move through phloem?

• The pressure-flow model explains how food, or
  sap, moves through a plant.
• The food moves from an area of high pressure to
  an area of low pressure