Across
1
Tissue that contracts for movement
4
Element found in all living things
5
Gas essential for breathing
6
Solid with repeating atomic pattern
9
Group of similar cells
10
Our home planet
Down
2
Biological catalyst
3
Icy body with a tail near the sun
5
Compound containing oxygen
7
Amplified beam of light
8
Precious yellow metallic element
11
Center of an atom or cell
12
Substance with pH below 7