Across
1
Tissue that contracts for movement
4
Substance with pH above 7
5
Precious yellow metallic element
7
Glass that splits light into spectrum
8
Biological catalyst
10
Mass per unit volume
12
Gas essential for breathing
Down
2
Curved glass that refracts light
3
Compound containing oxygen
6
Element found in all living things
9
Preserved remains of ancient life
11
Fourth state of matter