HISTORY OF LIFE ON EARTH

Cyanobacteria changed the early Earth's atmosphere by giving off...

• carbon dioxide

• ammonia

• hydrogen

• oxygen

Eukaryotes may have descended from...

• eubacteria

• archaebacteria

• cyanobacteria

• none of the above

This absorbs ultraviolet radiation

(a)  

All the living things on Earth today are grouped into...

• three kingdoms

• four kingdoms

• five kingdoms

• six kingdoms

Determining the age of a rock by comparing relative proportions of its radioactive isotopes is called...

• radioactive decay

• radiometric dating

• isotope dating

• half lives

The first step toward cellular organization may have been the gathering of amino acids into...

• macromolecules

• coacervates

• microspheres

• DNA molecules

This was required by the primordial soup model.

(a)  

Protists were the first organisms to exhibit cell specialization, which was only possible when they...

• grew large enough

• became eukaryotic

• evolved into fungi, plants, and animals

• became multicellular

Organisms were able to live safely on dry land after...

• cyanobacteria made oxygen, and ozone began to form

• the fifth mass extinction

• continental drift stopped

• archaebacteria made oxygen, and ozone began to form

These were the first to lay eggs with shells.

(a)