TOPIC 8: TRANSPORT IN PLANTS
8.1 TRANSPORT IN PLANTS
-Plants have a system to transport the water, nutrients and minerals they need
from the roots to the leaves.
-Plants contain two types of transport vessel:
→Xylem vessels – transport water and minerals from the roots to the stem and
leaves.
-Made of dead hollow cells joined end to end and have cell wall made of
cellulose and lining.
→Phloem tubes – transport food materials (mainly sucrose and amino acids) made
by the plant from photosynthesising leaves to non-photosynthesising regions in the
roots and stem.
-Made of many cells joined end to end and have holes in them.
-These vessels are arranged throughout the root, stem and leaves in groups called
vascular bundles (a group of xylem vessels and phloem tubes).
8.2 WATER UPTAKE
-Plants take water from the
soil (through the root hairs)
which is carried by xylem
vessels to all parts of the plant.
-The tip of the root hair is called the root cap and it’s a layer of cells that
protects the root as it grows through the soil.
→Root hairs: 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
Root hair cell from a cytoplasm of the root hair cell.
microscope:
How the Large Surface Area of a Root Hair Cell is Useful
-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 Roof to Leaf
1) Osmosis causes water to pass into the root hair cells, through the root cortex and into the
xylem vessels:
2) 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
INVESTIGATION:
1) 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)
2) 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
3) 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
8.1 TRANSPORT IN PLANTS
-Plants have a system to transport the water, nutrients and minerals they need
from the roots to the leaves.
-Plants contain two types of transport vessel:
→Xylem vessels – transport water and minerals from the roots to the stem and
leaves.
-Made of dead hollow cells joined end to end and have cell wall made of
cellulose and lining.
→Phloem tubes – transport food materials (mainly sucrose and amino acids) made
by the plant from photosynthesising leaves to non-photosynthesising regions in the
roots and stem.
-Made of many cells joined end to end and have holes in them.
-These vessels are arranged throughout the root, stem and leaves in groups called
vascular bundles (a group of xylem vessels and phloem tubes).
8.2 WATER UPTAKE
-Plants take water from the
soil (through the root hairs)
which is carried by xylem
vessels to all parts of the plant.
-The tip of the root hair is called the root cap and it’s a layer of cells that
protects the root as it grows through the soil.
→Root hairs: 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
Root hair cell from a cytoplasm of the root hair cell.
microscope:
How the Large Surface Area of a Root Hair Cell is Useful
-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 Roof to Leaf
1) Osmosis causes water to pass into the root hair cells, through the root cortex and into the
xylem vessels:
2) 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
INVESTIGATION:
1) 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)
2) 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
3) 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
