Across
1
Naturally occurring inorganic solid
4
Particle of light
5
The Red Planet
6
Substance with pH below 7
7
Unit of heredity
8
Substance with pH above 7
10
Force that attracts objects together
11
Push or pull on an object
Down
1
Tissue that contracts for movement
2
Nerve cell in the brain
3
Our home planet
4
Fourth state of matter
9
Center of an atom or cell