transpiration

What is a transpiration stream?

The flow of water which occurs when water diffuses out of open stomata causing a suction which pulls water up the stem, the water travels up the xylem as a continuous column of water

How does water enter the plant?

From the soil via osmosis through the root hair cells

What are the 4 main factors effecting transpiration?

Light intensity, temperature, air movement, humidity

What factor is this the graph of?

This could be light intensity or temperature

What factor is this the graph of?

Air movement

What factor is this the graph of?

Humidity

Can you explain why the graph of light intensity looks like this?

The increase is due to the stomata opening which will allow more water to evaporate, the plateau is because all the stomata are open so it cannot increase further

Can you explain why the graph of temperature looks like this?

The increase is due to more evaporation of water and more kinetic energy meaning faster diffusion, the plateau is because at too might a temp too much water is lost so the stomata closes

Can you explain why the graph of air movement looks like this?

Wind pushes away water vapour from near leaf which causes a steeper concentration gradient

Can you explain why the graph of humidity looks like this?

More humid means more water outside of leaf which makes the water potential gradient less steep so less water evaporates

Adaptations which allow them to photosynthesise as much as possible, while losing as little water as possible

Waxy cuticle - water proof to reduce evaporation

More stomata on underside of leaf - shaded from direct sunlight and heat

Curled leaves - creates a humid environment surrounding the stomata