Across
1
Element found in all living things
4
Biological catalyst
5
Center of an atom or cell
6
Path of a planet around the sun
Down
2
Ball of burning gas in space
3
Particle of light
4
Blocking of light by a celestial body
6
Compound containing oxygen
7
Tissue that contracts for movement
8
Reddish electrical conductor
9
Absolute temperature scale unit