What is the difference between a semi-permeable and a partially permeable membrane?
There is no real difference other than the wording; both semi-permeable and partially-permeable mean the ability to allow some substances to pass.
However, OCR examiners for AS biology have said that you should "not use the term semi-permeable when referring to cell membranes that allow water and other solutes to cross them" but should "refer to them as partially permeable."
Which term describes a membrane that allows the passage of some substances but prevents the passage of others?
How is the the filter paper used in filtration and the partially permeable membrane used in reverse osmosis similar?
Semipermeable membranes are used in osmosis. Semipermeable membranes let some molecules pass through them but not others, so they are partially or semi permeable. For example, the membrane may let smaller size molecules pass though but block larger molecules sort of like a sifter. Thus the two molecular substances can be separated.
An example of a semi-permeable membrane is the lipid bilayer of cells. In the process of reverse osmosis, thin film composite membranes (TFC or TFM) are used. These are semipermeable membranes manufactured principally for use in water purification or desalination systems. They also have use in chemical applications such as batteries and fuel cells. Another example of a semipermeable membrane is dialysis tubing.
A semipermeable membrane lets certain molecules, especially small ones, pass through and prevents other molecules from crossing. A semi permeable membrane is a barrier that lets some things in and not other things. The semipermeable membrane is found in somatic cells in the body. is generally formed by a phospholipid bilayer (two layers of fat molecules) which restrict molecules going in and out of the cell.
An impermeable membrane is that through which no substance can pass. Semipermeable membranes are those that let only solvents, like water, to pass through it. Permeable membranes are those that let solvent and solutes, like ions and molecules, to pass across it. There are also selectively permeable membranes, i.e., membranes that besides allowing the passage of solvent, let only some specific solutes to pass while blocking others. See link: