Osmosis-driven water uptake

Steps:

• Semipermeable membrane allows water to enter the solution inside a tube from surrounding water.
• Water moves from higher concentration (outside) to lower (inside) due to osmotic pressure.
• Influx of water increases liquid volume in the tube.
• Coloured oil drop, marking the meniscus, rises with the level.

Why C is correct:

• Osmosis is the diffusion of water across a semipermeable membrane from high to low water potential, directly causing volume increase and drop movement.

Why the others are wrong:

• A: Carbon dioxide release occurs in respiration but does not drive fluid movement here.
• B: Oxygen use reduces gas volume in respirometers, not liquid oil drop setups.
• D: Wire mesh provides support but does not cause osmotic flow or movement.

Final answer: C