Across
1
Unit of energy
3
Molten rock beneath Earth surface
4
Element found in all living things
7
Unit of force
12
Natural satellite of Earth
13
Tissue that contracts for movement
Down
2
Gas essential for breathing
5
Unit of heredity
6
Smallest unit of an element
8
Biological catalyst
9
Compound containing oxygen
10
Push or pull on an object
11
Icy body with a tail near the sun