Transpiration and translation

• How do root hair cells absorb water from the soil?

  there is a higher conc of water in the soils than in the root hair cells so water diffuses by osmosis.
• How do root hair cells absorb mineral ions from soil?

  there is a lower conc of mineral ions in the soil than in the root hair cell so active transport is required to absorb them against their conc gradient.
• Xylem tissue transports water and mineral ions from the roots to the stem and leaves
• Xylem tissue is made of hollow tubes of dead cells strengthened by lignin
• what do we call the flow of water molecules that pass through the xylem?

  the transpiration stream
• water can only move up the plant through the xylem
• Phloem tissue transports dissolved sugars and amino acids from the leaves to the rest of the plant
• phloem tissue is made up of elongated cells which form long tubes
• what do we call the flow of sap through the phloem?

  translocation
• cell sap can either move up or down the phloem.
• transpiration is the evaporation of water from the leaves of plants
• 4 factors that effect transpiration

  • temperature
  • light intensity
  • humidity
  • wind speed