Roots take up water and minerals from the soil. They have branches and root hairs that increase their surface area for absorption. Water enters roots through osmosis as root cells have a higher solute concentration than the soil. Minerals enter through active transport against their concentration gradient. Water moves through the root via two pathways - through the cell walls (apoplast pathway) or through the cytoplasm and plasmodesmata between cells (symplast pathway). Most water is drawn up through transpiration and replaced through the roots.

1. Transport in Angiosperms
9.2 part 1

2. Roots
A. Plants take in water and minerals through their roots
B. Roots have large surface area to allow for adequate uptake of
water and minerals
-they are branched and they have root hairs
C. Function of the cortex=to facilitate water uptake
D. Roots also act as anchorage to ground

3.  Zone of maturation: cells
differentiate into different types of
cells
 Zone of elongation: allows the
root to get deeper within the soil
 Meristematic region: rapid mitosis
of undifferentiated meristematic
cells
 Root cap: protects the
meristematic region

4. Roots and active transport
A. Mineral concentrations are often higher in the root than in
the soil
B. This suggests active transport (going against the
concentration gradient)
C. Cortex cells can absorb ions that are dissolved in the
water that is drawn by capillary action through the cortex
cell walls

5. Water Uptake By Roots
Roots take in water via osmosis
-Water in the soil contains a lower
concentration of solutes than the cytoplasm of root
cells
-This causes water to diffuse in to the roots

6. Water Uptake by Roots
Root cell Soil
High solute Low solute
H2O H2O
**Water diffuses (osmosis) to an area of high solute concentration
to reach equilibrium between the roots and the soil
**Minerals are taken in via active transport because the roots
have higher solute concentration than the soil

7. Water Uptake By Roots (continued)
Most absorbed water is eventually drawn to the rest of the
plant because of transpiration
-as water exits the leaves it must be replaced
To get water from the root hairs to the xylem, there
are two possible methods
-apoplast or symplast

8. Apoplast pathway
-water does not enter the root cells
-it travels by capillary action through the cell walls
of the cortex until it reaches the endodermis
-cells of the endodermis have Casparian strips
around them that are impermeable to water
-to pass through the endodermis the water must
follow the symplast pathway (the apoplast
pathway stops at the endodermis)

9. Symplast Pathway
-water enters the cytoplasm of the cells, but not the
vacuole
-water passes from cell to cell via the plasmodesmata
(connections of cytoplasm between cells)
-the water eventually enters the xylem

10. Movement Through Roots

11. Assignment: (in notebook)
Make a chart to compare apoplast
and symplast pathways