What substance can freely pass through the cell membranes?

Answer 1

Certain steroid hormones, cholesterol for example, can pass through the plasma membrane of the cell. Ions cannot pass through the plasma membrane but requires a channel protein. All cells in our body has phospholipid bilayer plasma membrane.

Answer 2

Thing that are very small like air or water.

Answer 3

Very small molecules can readily diffuse across the membrane - oxygen, water, carbon dioxide and certain electrolytes. Most other substances require a channel or a transport protein.

Answer 4

Small molecules can pass easily. Surface charge also affect it.

Answer 5

Not many molecules can pass. Molecules with low weight,surface charge etc