Osmosis and Water Potential in Blood Cells

Steps:

• Observe cell X appears shrunken, indicating water loss by osmosis.
• Recall osmosis: water moves from higher water potential (ψ) to lower ψ across a semi-permeable membrane.
• Determine net movement: shrinkage shows water exiting cell X into surrounding solution.
• Compare ψ: for water to exit, ψ of cytoplasm must be lower than ψ of solution.

Why C is correct:

• Water moves out of the cell when ψ of cytoplasm is lower than ψ of solution, as defined by osmosis direction from high to low ψ.

Why the others are wrong:

• A: Water enters if ψ cytoplasm > ψ solution, causing swelling, not observed.
• B: Inconsistent; water exits only if ψ cytoplasm < ψ solution, not higher.
• D: Extra "higher" mismatches; ψ cytoplasm is lower, not higher than solution.

Final answer: C