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

[EX Q]: Passage: The lungs of mammals are unique in having alveoli. These are tiny, sac-like structures. Each alveolus is surrounded by a network of very small blood vessels (see Figure below ). Because there are millions of alveoli in each lung, they greatly increase the surface area for gas exchange between the lungs and bloodstream. Human lungs, for example, contain about 300 million alveoli. They give the lungs a total surface area for gas exchange of up to 90 square meters (968 square feet). That's about as much surface area as one side of a volleyball court!. Answer: alveoli
[EX A]: What in mammalian lungs, increases the surface area for gas exchange?

[EX Q]: Passage: Insects spread disease and destroy crops. However, they are essential for pollinating flowering plants. Answer: insects
[EX A]: What are essential for pollination, but can spread disease and destroy crops?

[EX Q]: Passage: TiCl4(l) + 2Mg(s) Ti(s) + 2MgCl2(s) The only other alkaline earth that is widely used as the metal is beryllium, which is extremely toxic. Ingestion of beryllium or exposure to beryllium-containing dust causes a syndrome called berylliosis, characterized by severe inflammation of the respiratory tract or other tissues. A small percentage of beryllium dramatically increases the strength of copper or nickel alloys, which are used in nonmagnetic, nonsparking tools (such as wrenches and screwdrivers), camera springs, and electrical contacts. The low atomic number of beryllium gives it a very low tendency to absorb x-rays and makes it uniquely suited for applications involving radioactivity. Both elemental Be and BeO, which is a high-temperature ceramic, are used in nuclear reactors, and the windows on all x-ray tubes and sources are made of beryllium foil. Millions of tons of calcium compounds are used every year. As discussed in earlier chapters, CaCl 2 is used as "road salt" to lower the freezing point of water on roads in cold temperatures. In addition, CaCO 3 is a. Answer: low atomic number
[EX A]:
What aspect of beryllium allows it to absorb x-rays?