Across
1
Group of similar cells
4
Naturally occurring inorganic solid
8
Biological catalyst
9
Icy body with a tail near the sun
10
Infectious microscopic agent
11
Reddish electrical conductor
Down
2
Our home planet
3
Unit of heredity
4
Measure of matter in an object
5
Center of an atom or cell
6
Gas form of a liquid
7
Element found in all living things
12
Smallest unit of an element
13
Substance with pH below 7