Across
- 3. A common mineral in Earth's crust.
- 5. A system of measurement.
- 9. The force that pulls objects to Earth.
- 10. Preserved remains of ancient organisms.
- 11. An element found in all life forms.
- 14. The path of an object in space.
- 17. A particle of light.
- 19. The basic unit of matter.
- 20. The ability to do work.
- 23. An automatic response to stimuli.
- 24. A nerve cell in the brain.
- 25. Two or more atoms bonded together.
- 27. Anything that occupies space and has mass.
- 28. Carrier of genetic information.
Down
- 1. The fourth state of matter.
- 2. A path for electrical flow.
- 4. A protein that speeds up reactions.
- 6. A group of similar cells performing a function.
- 7. The smallest unit of life.
- 8. A device that emits coherent light.
- 10. The process of combining atomic nuclei.
- 12. A molecule protecting Earth from UV rays.
- 13. A swirling mass of fluid or air.
- 15. A disturbance that transfers energy.
- 16. A push or pull acting on an object.
- 18. A molecule essential for body functions.
- 21. A microscopic infectious agent.
- 22. The complete set of genetic material.
- 23. A machine designed to perform tasks.
- 26. A form of electromagnetic radiation.