Across
1
Gas essential for breathing
3
Unit of heredity
4
Ball of burning gas in space
6
Molten rock beneath Earth surface
8
Biological catalyst
10
Particle of light
11
Smallest unit of an element
Down
2
Amplified beam of light
3
Force that attracts objects together
5
Chemical element in table salt
7
Group of similar cells
9
Magnetic metallic element