Pathway Taken by Water (CIE IGCSE Biology)

• Osmosis causes water to pass into the root hair cells, through the root cortex and into the xylem vessels:

Pathway of water into and across a root

• Once the water gets into the xylem, it is carried up to the leaves where it enters mesophyll cells
• So the pathway is:

root hair cell → root cortex cells → xylem → leaf mesophyll cells

• The pathway can be investigated by placing a plant (like celery) into a beaker of water that has had a stain added to it (food colouring will work well)
• After a few hours, you can see the leaves of the celery turning the same colour as the dyed water, proving that water is being taken up by the celery
• If a cross-section of the celery is cut, only certain areas of the stalk is stained the colour of the water, showing that the water is being carried in specific vessels through the stem - these are the xylem vessels

Investigating water movement in plants using a stain