Across 2. The ability of organisms to change over time 3. A signal to which an organism responds 5. A device that produces magnified images of structures that are too small to see with the unaided eye 6. A well-tested explanation that unifies a broad range of observations 8. A decimal system of measurement whose units are scaled on multiples of 10 13. It allows light to pass through the specimen and uses two lenses to form an image 15. A logical interpretation based on prior knowledge or experience 16. Where the single cell is able to reproduce so that a group of cells develop from the single cell 17. The process of gathering information about events 18. The information gathered from observations 19. Involves internal feedback mechanisms that work in much the same way as a thermostat 20. A technique used to separate the cell into different parts 21. Where life can arise from nonliving matter 22. The new organism has a single parent 23. The variable that is deliberately changed Chapter 1 Vocabulary Down 1. Cells from two different parents unite to produce the first cell of the new organism 4. It uses beams of electrons, rather than light, to produce images 7. The variable that is observed and that changes in response to the manipulated variable 8. The combination of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes 9. The study of the living world 10. A proposed scientific explanation for a set of observations 11. An organized way of using evidence to learn about the natural world 12. A collection of living matter enclosed by a barrier that separates the cell from its surroundings 14. Variables in an experiment that are left unchanged NOTE: many of the clues are answered in 2 words!