Across
1
Tectonic landmass section
2
Path of a planet around the sun
4
Amplified beam of light
6
Nerve cell in the brain
11
Hottest planet in solar system
12
Compound containing oxygen
Down
2
Gas essential for breathing
3
Curved glass that refracts light
5
Positive particle in nucleus
7
Element found in all living things
8
Unit of heredity
9
Fourth state of matter
10
Absolute temperature scale unit