Transport in Flowering Plants
Root Hair Cells
- Root hairs are single-celled extensions of epidermis cells in
the root
- They grow between soil particles and absorb water and
minerals from the soil
- Water enters the root hair cells by osmosis
- This happens because soil water has a higher water potential
than the cytoplasm of the root hair cell
-
- The root hair increases the surface area of the cells
significantly
- This large surface area is important as it increases the rate
of the absorption of water by osmosis and mineral ions by
active transport.
Pathway of Water through Root to Leaf
- Osmosis causes water to pass into the root hair cells,
through the root cortex and into the xylem vessels.
- 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
Investigating the Pathway of Water
- 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.
Root Hair Cells
- Root hairs are single-celled extensions of epidermis cells in
the root
- They grow between soil particles and absorb water and
minerals from the soil
- Water enters the root hair cells by osmosis
- This happens because soil water has a higher water potential
than the cytoplasm of the root hair cell
-
- The root hair increases the surface area of the cells
significantly
- This large surface area is important as it increases the rate
of the absorption of water by osmosis and mineral ions by
active transport.
Pathway of Water through Root to Leaf
- Osmosis causes water to pass into the root hair cells,
through the root cortex and into the xylem vessels.
- 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
Investigating the Pathway of Water
- 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.
