• Explain how the Casparian strip prevents ions from reaching the xylem of the plant by the apoplast pathway.

  • the strip is impervious to water
  • forces the solutions to pass through the cell surface membrane
  • the phospholipid bilayer repels the charged particles
• How does flooding affect water potential in the soil?

  It lowers it
• Explain why large multicellular plants need a transport system.

  • long distance from external surface to cells
  • small surface area to volume ratio
  • diffusion is not fast nough
• What type of cell makes up cambium?

  Meristem
• For which macromolecule does a plant need both nitrogen and phosphorus?

  DNA
• Explain why water molecules can form hydrogen bonds with nitrate (NO3 –) ions

  • water is a polar molecule
  • nitrate ions are charged/ negative
  • hydrogen bonds form between the H on water and the O on nitrate ions
• Explain how a process that occurs in the cell surface membrane of the endodermis in the root causes water to enter the endodermis

  • solutes enter against the concentration gradient by active transport
  • which reduces the water potential of the endodermis
  • water diffuses by osmosis down the water potential gradient.