instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: Over 99 percent of all species that ever lived on Earth have gone extinct. Five mass extinctions are recorded in the fossil record. They were caused by major geologic and climatic events. Evidence shows that a sixth mass extinction is occurring now. Unlike previous mass extinctions, the sixth extinction is due to human actions. Answer: 99%
answer:
What percentage of all species that ever lived on earth have gone extinct?

question:
Passage: Most plant cells have a large central vacuole . It can make up as much as 90 percent of a plant cell's total volume. The central vacuole is like a large storage container. It may store substances such as water, enzymes, and salts. It may have other roles as well. For example, the central vacuole helps stems and leaves hold their shape. It may also contain pigments that give flowers their colors. Answer: vacuole
answer:
Most plant cells have a large central what?

question:
Passage: Atoms are neither created nor destroyed during a chemical change, but are instead rearranged to yield. Answer: atoms
answer:
What basic units are neither created nor destroyed during a chemical change, but are instead rearranged?