Across
1
Biological catalyst
2
Nerve cell in the brain
4
Mass per unit volume
6
Glass that splits light into spectrum
9
Unit of force
10
Tissue that contracts for movement
12
Path of a planet around the sun
Down
2
Center of an atom or cell
3
Curved glass that refracts light
5
Reddish electrical conductor
7
Natural satellite of Earth
8
Magnetic metallic element
11
Ball of burning gas in space