Which era is the earliest in Earth's history?

• Paleozoic Era

• Precambrian Era

• Mesozoic Era

• Cenozoic Era

During which era did reptiles dominate the Earth?

• Precambrian Era

• Paleozoic Era

• Mesozoic Era

• Cenozoic Era

The first evidence of zircon crystals appeared around ________.

• 4.6–3.8 BYA

• 3.5 BYA

• 3.0 BYA

• 500 MYA

The first prokaryotes appeared during this time.

• 3.0 BYA

• 3.5 BYA

• 4.6 BYA

• 500 MYA

Blue-green algae (cyanobacteria) appeared around ________.

• 4.6 BYA

• 3.0 BYA

• 500 MYA

• 250 TYA

During which period did trilobites and cephalopods exist?

• 251 MYA

• 500 MYA

• 3.5 BYA

• 65.5 MYA

The Jurassic and Cretaceous periods are part of which era?

• Mesozoic Era

• Paleozoic Era

• Precambrian Era

• Cenozoic Era

Homo erectus and mammals appeared around ________.

• 4.6 BYA

• 3.5 BYA

• 250 TYA

• 500 MYA

Living things work as a system that interacts with the nonliving environment.

• Biological system

• Energy and life

• Biology and society

• Interaction with the environment

Cells are the basic unit of life.

• Form and function

• Biological system

• The cellular basis of life

• Scientific inquiry