The Transpiration Stream Flashcards
What is adhesion?
The attraction between water molecules and the walls of the xylem vessels.
What is cohesion?
The attraction between water molecules caused by hydrogen bonds.
What is the transpiration stream?
The movement of water from the soil, through the plant, to the air surrounding the leaves.
What are root hair cells and what do they do?
Root hair cells are cells with a long extension that increases the surface area of the root.
Where are root hair cells found? (be specific)
On the epidermis of the roots of a plant
What do root hair cells do?
They absorb mineral ions and water from the soil.
How does water move in a root?
Down the concentration gradient across the root cortex to the endodermis of the vascular bundle.
What prevents water from travelling along the apoplast pathway all the way to the endodermis of the roots?
The casparian strip.
If the casparian strip blocks the apoplast pathway what pathway must the water then take?
Symplast
What is the movement of water in the root driven by?
An active process that occurs at the endodermis.
What is the endodermis?
The endodermis is a layer of cells surrounding the medulla and xylem. It is also known as a starch sheath as it contains starch.
What does the casparian strip do?
Blocks the apoplast pathway between the cortex and the medulla.
What does the casparian strip ensure?
That water and dissolved mineral ions have to pass into the cell cytoplasm through the membrane.
Mineral ions are actively pumped by what and where?
Transporter proteins in the plasma membrane.
Where are the mineral ions pumped to and from?
Pumped into the medulla from the cortex.
