Vocabulary

2. characterized by, living in, or being a close physical association between two or more dissimilar organisms
3. continuing or occurring again and again for a long time
7. an instrument for measuring the distance traveled
8. an electronic device whose electrical properties are modified by the action of light
9. a copy of usually printed material made with a process in which an image is formed by the action of light usually on an electrically charged surface
10. suitable for being photographed especially because of visual appeal
12. the science dealing with the atmosphere and its phenomena, including weather and climate
15. the part of the world in which life can exist
17. relating to, measured from, or as if observed from the earth's center
18. of, relating to, or arranged in or according to the order of time

1. balanced proportions
3. the science that deals with measuring time by regular divisions and that assigns to events their proper dates
4. a branch of science concerned with the interrelationship of organisms and their environments
5. to represent or arrange events to indicate coincidence or coexistence
6. a quantum of electromagnetic radiation
10. characteristic or factor
11. a science that deals with the history of the earth and its life especially as recorded in rocks
13. an instrument for indicating speed
14. of, relating to, or according to the methods or principles of geometry
16. a science that deals with the description, distribution, and interaction of the diverse physical, biological, and cultural features of the earth's surface