Water Potential Gradients in Osmosis

Steps:

• Slide 1 shows no visible RBCs and shrivelled blood, indicating hypotonic solution where cells swelled and burst from water influx.
• Slide 2 shows visible, crenated RBCs, indicating hypertonic solution where cells shrank from water efflux.
• Water moves across membranes from higher (less negative) to lower (more negative) water potential (ψ).
• Slide 1 external ψ > cell ψ; slide 2 external ψ < cell ψ, explaining observations.

Why B is correct:

• B accurately describes slide 1 cell ψ more negative than external ψ (water enters, causing burst) and slide 2 external ψ more negative than cell ψ (water exits, causing crenation), following the osmosis rule that water flows down ψ gradients.

Why the others are wrong:

• A: Identifies swelling and bursting correctly but reverses ψ comparison for slide 2.
• C: Incorrectly states solution ψ less negative and confuses net osmosis direction.
• D: Falsely claims ψ becomes similar via osmosis and vaguely describes movement.

Final answer: B