8.2 Water Uptake

Question 1

make sure you can label root hair cells in diagrams

Question 2

function of root hair cells

Answer 2

• increase the rate of absorption of water by osmosis and absorption of mineral ions by active transport

Question 3

how do root hair cells uptake of water and mineral ions

Answer 3

• they have a large surface area due to the long and narrow extensions
• cytoplasm has low water potential compared to surrounding soil water which causes uptake of water by osmosis
• root hair cells have many mitochondria so they can respire and provide the energy for active transport

Question 4

explain the pathway of water

Answer 4

1. water enters root hair cells in soil through osmosis
2. water passes from root hair cells to root cortex cells
3. water travels into the xylem where it travels up the stem to the leaves
4. water then enters the mesophyll cells

Question 5

describe the investigation using a suitable stain, the pathway of water through the above-ground parts of a plant

Answer 5

1. wash and place a plant like celery into a beaker of water as a control
2. add celery to two other beakers containing water but add red food dye to one and blue food dye to the other
3. leave all three plants in the sunlight for a few hours
4. cut cross-sections of the celery stalk and observe
5. the celery in plain water should have no visible change
6. the celeries in the water containing food dye should have stained xylem vessels as indicated in the diagram which indicates that water has been transported through the xylem vessels.