Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Dermal tissue covers the outside of a plant. It's like the plant's skin. Cells of dermal tissue secrete a waxy substance called cuticle. Cuticle helps prevent water loss and damage to the plant. Answer: cuticle

Answer: What do cells of dermal tissue secrete?

Question: Passage: Gases are also capable of dissolving in liquids. There are many examples of this in our everyday lives. For example, carbonated beverages contain dissolved carbon dioxide. We notice this when bubbles come out of solution when the beverage is opened. Another example is when oxygen from the air we breathe dissolves in our blood, where it is transported throughout the body. Fish and other aquatic organisms use gills to capture dissolved oxygen from their environments. Answer: oxygen

Answer: Fish and other aquatic organisms use gills to capture dissolved what?

Question: Passage: Since life began on Earth, there have been at least five major massive extinctions. Answer: five

Answer:
How many major massive extinctions have been since life began on earth?