Osmosis driven by water potential differences

Steps:

• Potato pieces start at 5 cm length; piece in X grows to 5.2 cm, indicating water uptake via osmosis.
• Piece in Y shrinks to 4.7 cm, indicating water loss via osmosis.
• Growth in X means solution X has higher water potential than potato cells, so water enters potato.
• Shrinkage in Y means solution Y has lower water potential than potato cells, so water exits potato.

Why A is correct:

• Water moves from higher to lower water potential; Y's lower potential causes potato shrinkage as defined by osmosis principles.

Why the others are wrong:

• B: Length increase results from water uptake, not sugar, as potato cells are semi-permeable to water but not solutes.
• C: Length decrease results from water loss, not sugar, as osmosis involves solvent movement.
• D: Not enough information (option incomplete).

Final answer: A