Role of transpiration
Transpiration is universal in flowering plants = the unavoidable result of plants having leaves adapted for photosynthesis.
Leaves have large surface area to absorb light and stomata to allow diffusion of gases but both features result in immense water loss.
Transpiration is not essential to bring water to leaves as osmotic processes could achieve this.
Materials such as mineral ions, sugars and hormones are dissolved in water and moved around the plant - water is carried up plant by transpiration pull.
Without transpiration, water would not be as plentiful and transport of materials would not be as rapid.
Factors affecting transpiration
Light: Stomata = openings in leaves through which carbon dioxide (for photosynthesis) diffuses inwards.
Photosynthesis only occurs in the light - stomata open = water moves out of leaf into atmosphere.
Increase of light intensity causes increase in rate of transpiration.
Temperature: Temp changes affect two factors that influence rate…