Across
1
Disturbance that transfers energy
3
Tissue that contracts for movement
4
Center of an atom or cell
7
Second lightest element
9
Unit of force
12
Path of a planet around the sun
13
Push or pull on an object
14
Precious yellow metallic element
Down
2
Absolute temperature scale unit
5
Group of similar cells
6
Our home planet
8
Curved glass that refracts light
10
Mass per unit volume
11
Biological catalyst