Across
1
Tectonic landmass section
3
Group of similar cells
6
Center of an atom or cell
7
Gas essential for breathing
11
Path of a planet around the sun
Down
2
Biological catalyst
4
Measure of matter in an object
5
Form of thermal energy
8
Substance with pH above 7
9
Icy body with a tail near the sun
10
Particle of light