Across
1
Amplified beam of light
4
Infectious microscopic agent
6
Unit of heredity
7
Group of similar cells
8
Unit of energy
12
Center of an atom or cell
Down
2
Measure of matter in an object
3
Positive particle in nucleus
5
Second lightest element
9
Hottest planet in solar system
10
Tissue that contracts for movement
11
Gas essential for breathing