Across
1
Basic unit of life
3
Biological catalyst
4
Compound containing oxygen
8
The Red Planet
9
Naturally occurring inorganic solid
11
Unit of heredity
Down
2
Center of an atom or cell
5
Icy body with a tail near the sun
6
Second lightest element
7
Push or pull on an object
10
Curved glass that refracts light
12
Fourth state of matter
13
Absolute temperature scale unit