Across
1
Preserved remains of ancient life
5
Biological catalyst
6
Magnetic metallic element
11
Blocking of light by a celestial body
12
Substance with pH below 7
Down
2
Positive particle in nucleus
3
Amplified beam of light
4
Absolute temperature scale unit
7
Path of a planet around the sun
8
Unit of heredity
9
Force that attracts objects together
10
Compound containing oxygen