Across
1
Chemical element in table salt
3
Positive particle in nucleus
5
Center of an atom or cell
6
Unit of heredity
7
Path of a planet around the sun
12
Solid with repeating atomic pattern
Down
2
Group of similar cells
4
Naturally occurring inorganic solid
8
Infectious microscopic agent
9
Fourth state of matter
10
Biological catalyst
11
Nerve cell in the brain