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

Input: Consider Input: Passage: Frogs and toads are adapted for jumping. Salamanders and newts may walk or swim. Caecilians live in the water or soil and are the only amphibians without legs. Answer: caecilians

Output: What is the only amphibian without legs?

Input: Consider Input: Passage: A lens that causes the light rays to bend away from its axis is called a diverging lens. Ray tracing is the technique of graphically determining the paths that light rays take. The image in which light rays from one point on the object actually cross at the location of the image and can be projected onto a screen, a piece of film, or the retina of an eye is called a real image. Thin lens equations are. Answer: diverging lens

Output: What do you call a lens that causes the light rays to bend away from its axis?

Input: Consider Input: Passage: The cell membrane is made up of a phospholipid bilayer, two layers of phospholipid molecules. Notice the polar head group of the phospholipid is attached to the phosphate, and the tails are two fatty acid chains. The head group and tails are attached by a glycerol backbone. Answer: cell membrane
Output: What basic cell structure is made up of a phospholipid bilayer and two layers of phospholipid molecules?