Across
1
The Red Planet
4
Group of similar cells
5
Basic unit of life
9
Element found in all living things
10
Chemical element in table salt
11
Our home planet
13
Compound containing oxygen
Down
2
Amplified beam of light
3
Curved glass that refracts light
6
Tissue that contracts for movement
7
Particle of light
8
Blocking of light by a celestial body
12
Unit of electric potential