Across
1
Unit of heredity
4
Absolute temperature scale unit
5
Particle of light
6
Tectonic landmass section
10
Force that attracts objects together
11
Substance with pH below 7
13
Second lightest element
Down
2
Gas essential for breathing
3
Reddish electrical conductor
7
Molten rock beneath Earth surface
8
Nerve cell in the brain
9
Natural satellite of Earth
12
Group of similar cells
14
Infectious microscopic agent
15
Magnetic metallic element