Across
1
Path of a planet around the sun
3
Group of similar cells
6
Smallest unit of an element
8
Biological catalyst
9
Blocking of light by a celestial body
12
Glass that splits light into spectrum
Down
2
Unit of power
4
Chemical element in table salt
5
Basic unit of life
7
Preserved remains of ancient life
10
Compound containing oxygen
11
Nerve cell in the brain