Movement of water through roots

?
  • Created by: elyornais
  • Created on: 20-03-15 10:25
What is the root hair cell?
The exchange surfaces in plants that are responisible for the absorption of water and mineral ions.
1 of 15
Give 2 reasons why the root hairs are efficient exchange surfaces.
They provide a large surface area as they are very long and occur in thousands. They have a thin surface layer- materials move over easily
2 of 15
How is water absorbed through the root hairs?
The soil solution that surrounds them have a high water potential while the root hairs and other cells have sugars, amino acids and mineral ions dissolved in them so have a lower water potential. Water moves by osmosis down this gradient.
3 of 15
What are the two ways that water travels after being absorbed into the root hair cell?
- The apoplastic pathway(apoplast) -The symplastic pathway(symplast)
4 of 15
How is water drawn into the root cortex?
Water is drawn into endodermal cells, pulls more water along behind it (cohesive properties of water molecules) creates a tension that draws water along the cell walls of the cells of the root cortex.
5 of 15
Why is there little resistance to the pull of water along cell walls?
There are many water-filled spaces in the mesh-like structure of the cellulose wall.
6 of 15
Where does the symplastic pathway take place?
Across the cytoplasm of the cells of the cortex.
7 of 15
What is the symplastic pathway?
Tiny openings called plasodesmata, each one is filled with a thin strand of cytoplasm. There is a continuous column of cytoplasm from root hair cell to xylem.
8 of 15
How does water move along the symplastic pathway?
Water enters by osmosis increases WP of root hair cell.->Root hair cell now has a higher WP than first cell in cortex.->osmosis->first cell in cortex now has higher WP than its neighbour-osmosis->carries on to each cell->WP gradient all the way.
9 of 15
How is water forced into living protoplast from the apoplastic pathway?
The waterproof band that makes up the casparian ***** prevents water from getting further along the cell wall.
10 of 15
How does water get into the xylem?
Active transport of salts from the endodermal cells. Requires energy so only occurs in living cells. Carrier proteins in the cell surface membrane.
11 of 15
What is the force that helps move water up the plant?
Root pressure.
12 of 15
How does temperature affect root pressure?
Increases with a rise in temp, decreases with low temp.
13 of 15
What do metabolic inhibitors, such as cyanide, do to the root pressure?
Prevent most energy release by respiration and cause root pressure to cease.
14 of 15
What does a decrease in oxygen do to root pressure?
Causes a reduction in root pressure.
15 of 15

Other cards in this set

Card 2

Front

Give 2 reasons why the root hairs are efficient exchange surfaces.

Back

They provide a large surface area as they are very long and occur in thousands. They have a thin surface layer- materials move over easily

Card 3

Front

How is water absorbed through the root hairs?

Back

Preview of the front of card 3

Card 4

Front

What are the two ways that water travels after being absorbed into the root hair cell?

Back

Preview of the front of card 4

Card 5

Front

How is water drawn into the root cortex?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Human, animal and plant physiology resources »