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Across 4. A characteristic that enables a living thing to survive in its environment. 5. a type of topsoil that is rich in minerals and has lots of humus. 7. a hard material that supports the skeletal system 8. the Sun and all the objects that orbit it 9. A device for measuring air pressure. 15. A nonliving part of an ecosystem. 17. The force put on a given area by the weight of the air above it. 18. a plant part that supports the plant 19. One of Earth’s large ecosystems, with its own kind of climate, soil, plants, and animals. 20. place where two or more bones join together

Down 1. tiny grains of worn or crushed rock, found mainly on seashores and in deserts. 2. When two forces cancel each other out. 3. A device that measures wind speed. 6. Change in velocity with respect to time. 10. a plant part that takes in water and grows under the ground 11. The blanket of gases that surrounds Earth. 12. The floor of an ocean, containing mountains, valleys, and plains. 13. to slope or slant 14. the act or process of moving 16. A large region of the atmosphere where the air has similar properties throughout. 17. The force one object applies to a second, as in Newton’s third law of motion, which states, "For every action, there is an equal but opposite reaction."