How does water potential influence water movement into plant roots from the soil?

How does water potential influence water movement into plant roots from the soil?

• A. Osmosis moves water from higher water potential to lower water potential; uptake occurs as roots lower their internal water potential by osmosis.
• B. Water moves from lower to higher water potential; roots raise internal potential by active transport only.
• C. Water flow is independent of water potential; it's driven solely by root pressure.
• D. Water potential has no effect.

Answer: (A)

Water moves from where the water potential is higher to where it is lower, and osmosis is the mechanism by which this happens. In soil, water potential is typically higher than inside root cells. Roots actively accumulate solutes, lowering their internal water potential (making it more negative). That creates a gradient that pulls water into the root cells by osmosis, allowing uptake from the soil. Other processes like root pressure can influence movement, but the driving force is the water potential gradient and water moving by osmosis down that gradient.

Water moves from where the water potential is higher to where it is lower, and osmosis is the mechanism by which this happens. In soil, water potential is typically higher than inside root cells. Roots actively accumulate solutes, lowering their internal water potential (making it more negative). That creates a gradient that pulls water into the root cells by osmosis, allowing uptake from the soil. Other processes like root pressure can influence movement, but the driving force is the water potential gradient and water moving by osmosis down that gradient.