Across
1
The Red Planet
4
Substance with pH above 7
6
Nerve cell in the brain
9
Second lightest element
10
Amplified beam of light
11
Unit of energy
Down
2
Group of similar cells
3
Tectonic landmass section
5
Substance with pH below 7
7
Infectious microscopic agent
8
Gas essential for breathing
12
Basic unit of life
13
Tissue that contracts for movement