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

Q: Passage: Most gemstones are not used exactly as they are found in nature. Usually, gems are cut and polished. Figure below shows an uncut piece of ruby and a ruby that has been cut and polished. The way a mineral splits along a surface allows it to be cut to produce smooth surfaces. Notice that the cut and polished ruby sparkles more. Gems sparkle because light bounces back when it hits them. These gems are cut so that the most amount of light possible bounces back. Other gemstones, such as turquoise, are opaque, which means light does not pass through them. These gems are not cut in the same way. Answer: opaque

A: What are gemstones known as when light cannot pass through them?
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Q: 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

A: What is a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate?
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Q: Passage: Cells make up all living things, including your own body. This picture shows a typical group of cells. But not all cells look alike. Cells can differ in shape and sizes. And the different shapes usually means different functions. Answer: cells

A:
What small biological structures make up all living things, including the human body?
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