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

Q: Passage: Population density is the average number of individuals in a population per unit of area or volume. For example, a population of 100 insects that live in an area of 100 square meters has a density of 1 insect per square meter. If the same population lives in an area of only 1 square meter, what is its density? Which population is more crowded? How might crowding affect the health of a population?. Answer: population density

A: What is the term for the average number of individuals in a population per unit of area or volume?
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Q: Passage: Most fungi get organic compounds from dead organisms. Fungi use their hyphae to penetrate deep into decaying organic matter. They produce enzymes at the tips of their hyphae. The enzymes digest the organic matter so the fungal cells can absorb it. Fungi are the main decomposers in forests. They are the only decomposers that can break down cellulose and wood. They have special enzymes for this purpose. Answer: hyphae

A: What do fungi use to penetrate deep into decaying matter?
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Q: Passage: The intertidal zone is the narrow strip along the coastline that is covered by water at high tide and exposed to air at low tide (see Figure below ). There are plenty of nutrients and sunlight in the intertidal zone. However, the water is constantly moving in and out, and the temperature keeps changing. These conditions require adaptations in the organisms that live there, such as the barnacles in Figure below . Answer: intertidal zone

A:
What zone is the narrow strip along the coastline that is covered by water at high tide and exposed to air at low tide?
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