Answer:
Root hair cell cytoplasm // Soil water
Explanation:
Water moves through the xylem vessels in a continuous transpiration stream:
root → stem → leaf
Transpiration produces a tension or ‘pull’ on the water in the xylem vessels by the leaves. Water molecules are cohesive so water is pulled up through the plant.
The transpiration stream has several functions. These include:
transporting mineral ions
providing water to keep cells turgid in order to support the plant
providing water to leaf cells for photosynthesis
keeping the leaves cool by evaporation
Root hair cells
The root hairs are where most water absorption happens. They are long and thin so they can penetrate between soil particles, and they have a large surface area for absorption of water.
Water passes from the soil water to the root hair cell’s cytoplasm by osmosis. This happens because the soil water has a higher water potential than the root hair cell cytoplasm:
Solution Water potential Concentration of dissolved solutes
Soil water High Low
Root hair cell cytoplasm Low High
Osmosis causes water to pass into the root hair cells, through the root cortex and into the xylem vessels
