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

[Q]: Passage: When there is no mass in a volume of space, the space is not curved. An object passing through such space would follow a straight line in our normal way of thinking of a straight line. Answer: curved
[A]: When there is no mass in a volume of space, the space is not what?

[Q]: Passage: The largest known virus, called mimivirus, is so large that scientists first mistook it for a bacterium. It was first discovered in amoeba, in 1992, and was identified as a virus in 2003. Scientists believe that mimivirus may cause certain types of pneumonia in humans. The core contains DNA, with the majority of the DNA in genes, and only 10% DNA of unknown function ("junk" DNA). Answer: mimivirus
[A]: What is the largest known virus?

[Q]: Passage: Even if you don't live in a place where leaves turn color in the fall, no doubt you've seen photos of their "fall colors" (see Figure below ). The leaves of many plants turn from green to other, glorious colors during autumn each year. The change is triggered by shorter days and cooler temperatures. Leaves respond to these environmental stimuli by producing less chlorophyll . This allows other leaf pigmentssuch as oranges and yellowsto be seen. Answer: chlorophyll
[A]:
When plants lose their leaves in the fall, what chemical is produced less to cause the change?