Transpiration + Plant Cells

• PHLOEM Tissues:

  • Phloem Tubes transport SUGARS, like Sucrose and Amino Acids

  They transport these Sugars, from where they're MADE in the LEAVES, to Other Parts of the Plant

  • The movement of Food Substances around the Plant, is known as TRANSLOCATION

  A) Sucrose

  
• Root Hair Cells:

  • Root Hair Cells are formed when the Cells on Plant Roots grow, into LONG HAIRS which stick out, into the SOIL

  Each Root is covered in MILLIONS of these Root Hairs --> this gives the Plant a LARGER SURFACE AREA for Absorbing Water from the Soil

  -

  • Water is taken in by OSMOSIS (Higher Concentration of Water in the Soil)
  • Mineral Ions are taken in by ACTIVE TRANSPORT (Lower Concentration of Mineral Ions in the Soil)

  A) Nucleus

  B) Vacuole

  C) root

  
• XYLEM Tissues:

  • Xylem Tubes transport WATER and MINERAL IONS

  They Carry Water and Mineral Ions from the ROOTS, up the Shoot, then to the LEAVES in the "Transpiration Stream"

  • Their walls are strengthened by LIGNIN

  A) Mineral Ions

  
• [Transpiration] is the EVAPORATION of Water from the Leaves of a Plant, through the Stomata

  A) -

  
• Transpiration is caused by the Evaporation of Water, by the molecules DIFFUSING of the Surface of the Leaves

  • This Evaporation creates a Shortage of Water in the Leaf, so MORE WATER is drawn up from the Roots of the Plant, through the Xylem Tissues

  --> More Water is drawn up from the Roots AT THE SAME TIME the Water Molecules diffuse off the Leaf's Surface, so there is a CONSTANT Transpiration Stream of Water through the Plant

  A) Roots

  B) Leaves

  
• [Factors Affecting TRANSPIRATION]

  • LIGHT INTENSITY - The Brighter the Light, the GREATER the Transpiration Rate

  --> The Stomata begin to close when it gets darker, because Photosynthesis can't happen in the dark, so when the Stomata are closed, VERY LITTLE Water can escape, stopping the Transpiration

  • TEMPERATURE - The Hotter it is, the FASTER Transpiration happens

  --> When it's Warm, the Water Particles have MORE ENERGY to Evaporate and Diffuse out of the Stomata, causing Transpiration to occur FASTER

  A) -

  
• [Factors Affecting TRANSPIRATION]

  • WIND SPEED - The Higher the Wind Speed around a Leaf, the GREATER the Transpiration Rate

  --> When Wind Speed is low, Water Vapour in the air just Surrounds the Leaf, and DOESN'T move AWAY (affecting the Concentration Gradient)

  When it's Windy, Water Vapour in the air is SWEPT AWAY, maintaining a LOW Concentration of Water in the Air (which INCREASES the Rate of Diffusion)

  • HUMIDITY - The LOWER the Humidity, the FASTER Transpiration occurs

  --> Humid Air means there is already lots of WATER, so there is NO DIFFERENCE in the Concentration Gradients

  A) -