Given a scientific passage and an answer, generate a question for the given answer.

Input: Consider Input: Passage: "Dry ice," or solid carbon dioxide, is a substance that sublimes at atmospheric pressures. Dry ice is very cold (78C) and so is used as a coolant for goods such as ice cream that must remain frozen during shipment. Because the dry ice sublimes rather than melting, there is no liquid mess associated with its change of state as the dry ice warms. As you may have seen in demonstrations, dry ice merely transforms from a solid to a cold, steamy looking gas. Ferrocene (an iron-containing compound) is usually purified by sublimation by gentle warming at atmospheric pressure. In the Figure below , you can see the reddish ferrocene crystals deposited on the outside of that tube. Deposition is the change of state from a gas to a solid. Answer: dry ice

Output: What is the common term for solid carbon dioxide, which is used as a coolant?

Input: Consider Input: Passage: Membranes Biological membranes surround cells and serve to keep the insides separated from the outsides. They are formed of phospholipid bilayer1 s, which by definition are a double layer of fatty acid2 molecules (mostly phospholipid3 s, lipids containing lots of phosphorus). Proteins4 serve very important functions in cellular membranes. They are active transports in and out of the cell, acting as gatekeepers. They relay signals in and out of the cell. Proteins are the site of many enzymatic reactions in the cell, and play a role in regulation of cellular processes. Answer: biological membranes

Output: What is it that surrounds cells and serve to keep the insides separated from the outsides?

Input: Consider Input: Passage: Seawalls and breakwaters are built parallel to the shore. Answer: shore
Output: Seawalls and breakwaters are built parallel to what?