Question

osmosis across a cell membrane can be modeled using a u - shaped tube. one solution is poured into one end of the tube, and another solution is poured into its other end. both solutions are made by dissolving a solute such as salt in water, but the two solutions do not have the same concentration. at the bottom of the tube, there is a semipermeable membrane that represents a cell membrane. complete the sentences. to model osmosis across a cell membrane, the scientists who created this model used a semipermeable membrane that allows water to pass through it. like a cell membrane, the membrane in the model dropdown molecules to pass through it. the dropdown options are: allows all types of, allows only certain types of, does not allow any

Explanation:

A cell membrane is selectively (semi - )permeable, meaning it allows only certain substances (molecules) to pass through. The model's membrane is meant to represent the cell membrane, so it should have the same property of allowing only certain types of molecules to pass through, while allowing water (as in osmosis) to pass. The other options ("allows all types of" would be a fully permeable membrane, not semi - permeable; "does not allow any" is incorrect as osmosis involves water movement) don't fit the definition of a semipermeable membrane or the function of a cell membrane.

Answer:

allows only certain types of