phloem structure

• What are the two types of transport tissue in plants?

  Xylem and phloem
• What is the primary function of xylem vessels?

  To carry water and minerals up the plant
• What process occurs in the leaves that produces glucose?

  Photosynthesis
• What are the compounds formed from glucose called?

  Assimilates
• What is the main role of phloem in plants?

  To transport assimilates from leaves to other parts
• What is the fluid that moves in the phloem called?

  Phloem sap
• How does phloem differ from xylem in terms of tissue type?

  Phloem is a living tissue
• What are the two types of tissue that make up phloem?

  Sieve tube elements and companion cells
• What is a sieve tube element?

  A long line of cells for transporting sap
• What happens to the organelles in sieve tube element cells?

  Most organelles are lost
• What are sieve plates?

  Modified end walls with large pores
• Why can't sieve tube element cells produce large amounts of ATP?

  They have lost most organelles
• What is the role of companion cells?

  To provide essential molecules to sieve tube elements
• What do companion cells contain that sieve tube elements do not?

  A nucleus and mitochondria
• What are plasmodesmata?

  Microscopic channels linking companion and sieve tube cells
• How do companion cells assist sieve tube elements?

  By moving ATP and proteins through plasmodesmata
• What structural component do phloem tubes lack that xylem tubes have?

  Lignin in the cell walls
• What types of tissues provide support in phloem?

  Fibers and sclereids
• How do fibers and sclereids differ in phloem?

  Fibers are long and narrow; sclereids vary in shape