1				2		3
			4
5					6
7
	8
										9								10
	11
				12
						13		14
																		15
16
	17
												18
				19
														20

Across 3. A colorless, odorless, gaseous element, with the atomic number 8, constituting about one-fifth of the volume of the atmosphere and present in a combined state in nature. 4. The smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound. 5. A chemical compound that does not contain the element carbon. 7. Very large organic molecule made of carbon,hydrogen, oxygen, nitrogen, and phosphorus, that contains the instructions cells need to carry out all the functions of life. 8. When two or more elements combine chemically. 9. Energy-rich organic compound, such as a fat,oil, or wax, that is made of carbon, hydrogen, and oxygen. 11. Ribonucleic acid, a nucleic acid that plays an important role in the production of proteins. 12. The movement of materials through a cell membrane using energy. 14. The diffusion of water molecules through a selectively permeable membrane. 15. The genetic material that carries information about an organism and passed from parent to offspring. 16. The movement of materials through a cell membrane without using the cell's energy. 17. A protein that speeds up chemical reactions in a living thing. 18. The process by which molecules move from an area of higher concentration to an area of lower concentration. 19. A chemical compound composed of two hydrogen atoms and one oxygen atom. 20. Large organic molecule made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.

Down 1. A property of cell membranes that allows some substances to pass through, while others cannot. 2. A colorless, odorless, gaseous element, with the atomic number 7, that constitutes about four-fifths of the volume of the atmosphere and is present in combined form in animal and vegetable tissues, esp. in proteins. 3. A chemical compound in living things that contains the element carbon. 6. A small molecule that is linked chemically to other amino acids to form proteins. 8. An energy-rich organic compound made of the elements carbon, hydrogen, and oxygen. 10. A compound composed of one carbon atom comined with two oxygen atoms. 13. Any substance that cannot be broken down into simpler substances.