Early Earth

How old is the Earth?

• 3.5 billion year

• 3.5 million years

• 4.6 billion years

• 4.6 million years

What era are we in?

• Cenozoic

• Mesozoic

• Paleozoic

• Proterozoic

In which era do amphibians begin to evolve?

• Precambrian Era

• Paleozoic Era

• Mesozoic Era

• Cenozoic Era

In which era do humans begin to evolve?

• Precambrian Era

• Paleozoic Era

• Mesozoic Era

• Cenozoic Era

How many eras have occurred in the earth's history?

• 2

• 4

• 6

• 10

How did water vapor begin to appear on earth?

• cell respiration

• photosynthesis

• human sweat

• asteroids hitting the surface

Estimated first life on earth was ____ .

• 3.5 million years ago

• 3.5 billion years ago

• 4.6 million years ago

• 4.6 billion years ago

What was the first life on earth?

• plants

• single-celled organisms - cyanobacteria

• fish

• amphibians

With the introduction of oxygen, life became more abundant in the oceans and more complex organisms began to form.

• True

• False

There was less carbon dioxide in the earth's atmosphere 4 billion years ago than there is today.

• True

• False