Phosphorus chains from the backbone of DNA and ____.
The mass extinction at the end of the Permian period was likely caused by ___ and huge ____.
Quaternary period water levels fell because so much water was frozen in _____.
A ___ is a group of organisms that includes an ancestor and all of its descendants.
In late 2010 NASA scientists proposed the notion that the elements for life, carbon, hydrogen, oxygen, nitrogen, phosphorus and _____ may have additional members.
It could be possible that life on other planets may have been formed by ____ not used on earth.
Omnivores evolved to keep animal population and ____ growth in check.
What event froze the earth and covered it in snow?
Homosapiens literally means "wise human". This refers to our large _____.
All modern classification systems have their roots in the ____ classification system.
The Cenozoic era was the age of the _____.
Herbivores evolved because of the abundance of ____ life.
One billion years ago the first ____ organisms evolved.
What do we base the history of life on earth off of?
Dinosaurs evolved into carnivores because of ____ oxygen levels.
During the Jurassic period insects evolved to _____ the flowers.
The evolution of Eukaryotic cells is explained by ____ theory.
The first molecules formed about 4 ___ years ago.
Omnivores evolved to keep ___ population and vegetation growth in check.