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Across 2. _________ rays have the shortest wavelengths, highest frequencies and have the greatest amount of energy; they can be used to kill cancer cells in the body (Fact 214) 5. the _____________ of a wave is the distance between corresponding parts,, from crest to crest or from trough tp trough (Fact 204) 8. There are 7 basic types of electromagnetic waves, radio waves, microwaves, infrared rays, visible light rays, _____________ rays and gamma rays (Fact 211) 10. a person's ___________ is its physical appearance (Fact 179) 12. _________ is the second largest planet, is the 6th planet from the sun, is the least dense of all the planets , and has the largest rings (Fact 62) 14. the first cells were __________ organisms that released oxygen into the atmosphere (Fact 84) 17. the core is the innermost layer of the Earth and is made mostly of ______ (Fact 124) 21. a person's ____________ is its genetic makeup or allele combinations (Fact 180) 23. electromagnetic rays that humans can see are called _________ _______ (Fact 212) 24. the ________ is the outermost layer of the Earth and ranges from 5-100 km thick (Fact 119) 25. a wave is a disturbance that transfers __________ from one place to another (Fact 201)

Down 1. _____________ do not require a medium (material) to pass through, they consist of vibrating electrical and magnetic fields that move through space at the speed of light (Fact 209) 3. the ____________ of a wave is a measurement of the displacement of the wave from its rest position (Fact 203) 4. animal cells do not have ______ _______ (Fact 159) 6. the high point of a wave is its crest and the low point of the wave is its _________ (Fact 202) 7. the ___________ of a wave is the number of complete waves that pass through a given point in a certain amount of time (Fact 205) 9. the _____________ Era is known as the Age of the Mammals (Fact 98) 11. the largest mass extinction in the history of life on Earth took place at the end of the_________ Era most likely due to climate change (Fact 92) 13. a meteor or a ________ _________ is a meteoroid that has entered Earth's atmosphere, heated up, and produced a streak of light (Fact 69) 15. ______ ______ can penetrate most matter except lead; too much exposure to these rays can cause cancer (Fact 213) 16. __________ cells are the third type of cell, they are smaller then the other two types and they lack nuclei (Fact 166) 18. the _______ is the middle layer of Earth, is mostly solid, and accounts for most of the Earth's mass (Fact 122) 19. ________ has the densest atmosphere of all the inner planets; it is made mostly of sulfuric acid and carbon dioxide (Fact 37) 20. __________ are small rocky bodies left over from the formation of the solar system (Fact 66) 22. the two main types of cells are ___________ and plant (Fact 158)