Across
1
Blocking of light by a celestial body
4
Element found in all living things
8
Curved glass that refracts light
10
Group of similar cells
11
Substance with pH below 7
Down
2
Unit of heredity
3
Center of an atom or cell
5
Icy body with a tail near the sun
6
Gas form of a liquid
7
Tectonic landmass section
9
Biological catalyst
12
Fourth state of matter