Topic 9- Plants Flashcards
What is the walls of the xylems that are lined with a waterproof polymer called?
Lignin
What are xylem vessels? (describe them)
- Long, tubes of cells that run up the stem of plants.
- The vessel elements in the xylem are dead.
- There are no cell walls at the ends of each vessel element.
Function of xylem vessels?
continuous tube for water to flow through
What do Lignins do?
Lignins reinforces the walls of the vessel elements to provide structural support.
What is Transpiration?
Where most of the water in the leaves evaporates.
What creates tension in the xylem?
The loss of water from the leaves creates tension in the xylem.
What is tension?
Tension is the formation of hydrogen bonds between water molecules and the sides of the xylem vessel elements.
What is cohesion?
Individual water molecules also form hydrogen bonds with each other.
What happens in the plants with Tension and Cohesion?
The combination of cohesion and tension together continuously pull water upwards to replace water that has been lost in the leaves by transpiration.
What happens when water is pulled up the stem?
The water potential at the bottom of the plant decreases.
How does water diffuses into roots?
Water diffuses into the roots via osmosis down its water potential gradient.
