# Reserved new files · first response

Staff chooses one file after feedback and a delay. Learners use the assigned source/task only. Capture this first response before its matching later page. All numbers and descriptions are original conceptual models, not actual investigation results.


## E1 first

**Source:** Neutral N is 9 mmol/L inside and 3 mmol/L outside, cannot cross the bare bilayer and has a suitable passive carrier. Neutral P is 2 mmol/L inside and 5 mmol/L outside; an ATP-coupled pump carries P outward. A separate pouch has 0.12 mol/L impermeant neutral solute inside and 0.28 mol/L outside. Water crosses; solute does not; temperature and initial hydrostatic pressure are equal. A word map describes water on both sides of a phospholipid bilayer, a channel, an external carbohydrate chain on a glycoprotein and cholesterol among tails in an animal model. It has no scale or full component inventory.

**Task:** For N and P give mechanism, net direction, concentration evidence and energy statement; explain net movement. Describe head/tail orientation, one role each for channel, glycoprotein and cholesterol, and a model limit. Predict initial net water movement for the pouch, naming permeability, temperature and pressure conditions, the moving substance and one unavailable outcome. Preserve first work before the later page.