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Across 1. Two cells from different parents unite to produce the first cell of an organism. 6. Process that separates the cell into different parts. 10. The idea that life comes from nonliving matter. 11. The variable that is observed and that changes in response to the manipulated variable. 13. An experiment in which only one variable is changed at a time. 14. A group of cells that develop from a single cell. 15. The science that seeks to understand the living world. (The study of life) 16. Combinations of chemical reactions through which an organism builds up or breaks down materials. 18. Smallest units considered to be alive. (Collection of living matter enclosed by a barrier that separates it from its surroungings.) 19. A proposed scientific explanation for a set of observations. (An educated guess) 21. A logical interpretation based on prior knowledge or experience. 22. The ability of a group of organisms to change over time. 23. An organized way of using evidence to learn about the natural world. The body of knowledge scientists have built up over the years.

Down 2. Uses beams of electrons to produce images 1000X more detailed than light microscopes. 3. The process of gathering information about events or processes in a careful orderly way using the senses. 4. Allows light to pass through a specimen and uses lenses to form an image. 5. A signal to which an organism responds. 7. The variable that is deliberately changed in an experiment. 8. A new organism is produced that has a single parent. 9. A decimal system of measurement whose units are based on physical standards and are scaled multiples of 10. 12. An organism keeping its internal conditions constant. 16. A device that produces magnified images of structures that too are small to see with the unaided eye. 17. A well tested explanation that unifies a broad range of observations. 20. Information gathered from observations.