A Levels Biology (9700)•9700/12/M/J/21

Explanation
Selective permeability and concentration gradients determine substance movement
Steps:
- Membrane permeable to water and saccharides (sucrose, glucose), allowing diffusion down gradients.
- Statement 1 false: Sucrose higher inside (0.03 mol dm⁻³) vs. outside (0 mol dm⁻³), so diffuses out.
- Statement 2: Glucose higher outside (0.01 mol dm⁻³) vs. inside (0 mol dm⁻³), so diffuses in; but if "no movement" correct per option D, implies no gradient or impermeability to glucose.
- Statement 3 incomplete and diagram missing, preventing full evaluation.
Why D is correct:
- Option D selects 2 and 3, aligning with assumption that glucose does not enter (perhaps membrane selectively blocks despite "saccharides" label) and 3 involves osmosis (higher internal solute draws water in).
Why the others are wrong:
- A includes 1, but sucrose moves out due to gradient.
- B only 1, ignores 2 and 3.
- C includes 1, false as above.
Not enough information for full confirmation without statement 3 and diagram.
Final answer: D
Topic: Movement into and out of cells
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