Oxygen dependence signals energy-requiring active transport

Steps:

• Active transport moves ions against concentration gradients using ATP energy.
• ATP is produced via aerobic respiration, which requires oxygen.
• Low oxygen limits respiration, reducing ATP availability.
• Slower ion uptake in low oxygen confirms energy dependence, characteristic of active transport.

Why D is correct:

• Active transport definition: energy-intensive process using ATP from oxygen-dependent respiration; reduced oxygen slows ATP production, directly impairing uptake.

Why the others are wrong:

• A: Partially permeable membranes enable passive diffusion, not energy-requiring active transport.
• B: Large surface area boosts passive diffusion rates, unrelated to active energy use.
• C: Lower water potential drives passive osmosis for water, not active ion movement.

Final answer: D