Across
1
Second lightest element
4
Tectonic landmass section
5
Biological catalyst
7
Ball of burning gas in space
11
Positive particle in nucleus
12
Smallest unit of an element
Down
2
Naturally occurring inorganic solid
3
Tissue that contracts for movement
6
Substance with pH above 7
8
Unit of heredity
9
Force that attracts objects together
10
Group of similar cells
13
Unit of power