12.3-12.6 Review 2025

What is the time range for the "Age of Mammals" in the geologic time scale?

• 250 mya - 65 mya

• 550 mya - 250 mya

• 65 mya - Present

• 145.5 mya - 65 mya

Which era is known as the "Age of Dinosaurs"?

• Cenozoic

• Mesozoic

• Paleozoic

• Precambrian

What is the collective name for the Hadean, Archean, and Proterozoic eons?

• Paleozoic

• Mesozoic

• Precambrian

• Cenozoic

Approximately how old is the Earth/Solar System?

• ~ 4.55 billion years old

• ~ 3.5 billion years old

• ~ 2.5 billion years old

• ~ 1.5 billion years old

Did the early Earth resemble modern Earth?

• Yes, it had a similar atmosphere and oceans

• No, there was no atmosphere, and the crust took time to cool

• Yes, it had a similar climate and life forms

• No, it was covered in ice

Did the atmosphere of early Earth resemble modern Earth?

• Yes, it had oxygen and an ozone layer

• No, it lacked oxygen gas and had no ozone layer

• Yes, it was rich in carbon dioxide and nitrogen

• No, it was filled with methane and ammonia

What is the oldest evidence of life on Earth?

• ~ 4.55 billion years old

• ~ 3.5 billion years old

• ~ 2.5 billion years old

• ~ 1.5 billion years old

What was this earliest life like?

• Multicellular, eukaryotes that were terrestrial

• Unicellular, prokaryotes that were aquatic

• Multicellular, prokaryotes that were aquatic

• Unicellular, eukaryotes that were terrestrial

Why do we believe that the earliest life began in the sea?

• Because land was more suitable for life

• Because the sea provided more food

• Because simple, cellular life would not have survived on land without an ozone layer

• Because the sea was warmer

Why is the ozone layer important for living things?

• It provides oxygen for breathing

• It reflects/absorbs the majority of ultraviolet light from the sun

• It helps in the formation of clouds

• It increases the temperature of the Earth