Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

[EX Q]: Most have cells that are not able to exchange gases with the outside environment do multicellular organisms need transport systems.
[EX A]: Why do multicellular organisms need transport systems?

[EX Q]: The newest, outer layers of secondary xylem are called sapwood.
[EX A]: What are the newest, outer layers of secondary xylem called?

[EX Q]: Hydrocarbons are made of one carbon and four hydrogen atoms.
[EX A]:
Which molecules are made of one carbon and four hydrogen atoms?