Across 1. logical interpretation based on prior knowledge and experience 4. technique in which cells are broken into pieces and the different cell parts are separated. 5. microscope that forms an image by focusing beams of electrons on a specimen 8. a disproven hypothesis stating that life could arise from non-living matter 10. use of one or more of the senses - sight, hearing, touch, smell, and sometimes taste - to gather information. 11. collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life 15. decimal system of measurement based on certain physical standards and scaled on multiples of 10 16. factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable; also known as a dependent variable. 18. a signal to which an organism responds 19. evidence; information gathered from observations 20. process by which a single parent reproduces by itself 22. process by which cells from two different parents unite to produce the first cell of a new organism 23. well-tested explanation that unifies a broad range of observations

Down 2. microscope that allows light to pass through a specimen and uses two lenses to form an image 3. factor in an experiment that a scientist purposely changes; also known as an independent variable. 6. a test of the effect of a single variable by changing it while keeping all other variables the same. 7. organized way of using evidence to learn about the natural world; also, the body of knowledge that scientists have built up after years of using this process. 9. process by which organisms maintain a relatively stable internal environment 12. set of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes 13. group of cells grown in a nutrient solution from a single original cell 14. device that produces magnified images of structures that are too small to see with the unaided eye 17. possible explanation for a set of observations or possible answer to a scientific question 21. study of life; science that seeks to understand the living world