Across
1
Naturally occurring inorganic solid
4
Unit of force
6
Curved glass that refracts light
7
Center of an atom or cell
12
Natural satellite of Earth
Down
2
Infectious microscopic agent
3
Group of similar cells
5
Substance with pH below 7
8
Magnetic metallic element
9
Biological catalyst
10
Absolute temperature scale unit
11
Element found in all living things
13
Positive particle in nucleus