Across
1
Group of similar cells
3
Unit of energy
5
Substance with pH below 7
6
Element found in all living things
7
The Red Planet
9
Biological catalyst
12
Chemical element in table salt
13
Force that attracts objects together
Down
2
Push or pull on an object
4
Blocking of light by a celestial body
8
Solid with repeating atomic pattern
10
Fourth state of matter
11
Nerve cell in the brain