How can we help?
You can also find more resources in our
Select a category
Something is confusing
Something is broken
I have a suggestion
What is your email?
What is 1 + 3?
Chapter 12:History of Life on Earth
The estimation of the age of an object by measuring its content of certain radioactive isotopes
Charged particles (radiation)
The time required for half of a sample of radioactive substance to disintegrate by radioactive decay or by natural processes
Short chains of amino acids can gather into tiny water droplets
The preserved or mineralized remains (bone, tooth, or shell) or imprint of an organism that lived long ago
Prokaryotes that contain a chemical called peptidoglycan in their cell walls
Prokaryotes that lack peptidoglycan in their cell walls and have unique lipids in their cell membranes
The theory that mitochondria are descendants of symbiotic, aerobic (oxygen-requiring) eubacteria and chloroplasts are descendents of symbiotic, photosynthetic eubacteria
Make up a large, varied group that includes both multicellular and unicellular organisms
The death of all members of a species
And episode during which large numbers of species become extinct
Symbiotic associations between fungi and the roots of plants
A kind of animal with a hard outer skeleton, a segmented body, and paired, jointed limbs
The movement of Earth's land masses over Earth's surface through geologic time