2.57B - Factors affecting transpiration

Edexcel IGCSE Biology

what are the four main environmental conditions that impact the rate of transpiration?

* air movement/wind
* humidity
* temperature
* light intensity

effect of high air movement on the rate of transpiration

* increases transpiration rate
* good airflow removes water vapour from the air surrounding the leaf
* sets up concentration gradient between leaf and air
* increases water loss

effect of high humidity on rate of transpiration

* decreases transpiration rate
* humidity is measure of moisture in the air
* when air is saturated with water vapour the concentration gradient is weaker so less water is lost

effect of high light insensity on transpiration

* increases transpiration rate
* guard cells are responsive to light intensity
* when light intesntiy is high they are turgid and the stomata open allowing water to be lost

effect of high light intensity on rate of transpiration

* increases transpiration rate
* higher temperature = particles have more kinetic energy
* water molecules evaporate from the mesophyll and diffuse away faster