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

Passage: Most plants continue to grow as long as they live. They grow through a combination of cell growth and cell division (mitosis). The key to plant growth is meristem, a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate. Meristem allows plant stems and roots to grow longer (primary growth) and wider (secondary growth). Answer: meristem
What is a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate?

Passage: Distillation is an effective method to separate mixtures comprised of two or more pure liquids. Distillation is a purification process where the components of a liquid mixture are vaporized and then condensed and isolated. In simple distillation, a mixture is heated and the most volatile component vaporizes at the lowest temperature. The vapor passes through a cooled tube (a condenser), where it condenses back into its liquid state. The condensate that is collected is called distillate. Answer: distillation
What is a purification process where the components of a liquid mixture are vaporized and then condensed and isolated?

Passage: The average annual temperature on Earth has been rising for the past 100 years. Answer: rising
Has the average annual temperature on earth been rising or falling for the past 100 years?