Across
1
Element found in all living things
4
Tissue that contracts for movement
6
Nerve cell in the brain
10
Biological catalyst
11
Icy body with a tail near the sun
Down
2
Path of a planet around the sun
3
Blocking of light by a celestial body
5
Push or pull on an object
7
Unit of energy
8
Reddish electrical conductor
9
Unit of electric potential
12
Curved glass that refracts light