THE BIRTH OF EARTH
Approximately how many years ago did the Solar System begin to form?
Approximately 4.5 billion years ago.
What essential substance accumulated on Earth's surface when the planet cooled approximately 3.8 billion years ago?
Liquid water.
What name was given to some of Earth's earliest continental masses?
Cratons.
What major evolutionary event occurred between approximately 540 and 485 million years ago?
The Cambrian Explosion.
Approximately how many million years ago did the asteroid impact associated with the extinction of dinosaurs occur?
Approximately 66 million years ago.
What two materials made up the cloud from which the Solar System formed?
Gas and dust.
What type of organisms appeared on Earth approximately 3.7 billion years ago?
Microscopic organisms.
What was the name of an early, relatively small continental assembly that may have formed around 3.3 billion years ago?
Vaalbará.
What happened to biodiversity during the Cambrian Explosion?
Biodiversity increased significantly as many new animal groups appeared and diversified.
What group of animals became more common and diversified after the extinction event that eliminated the dinosaurs?
Mammals.
What happened to water on early Earth before the planet cooled enough to form oceans?
Water existed mainly as vapor because temperatures were too high for stable liquid oceans.
What were cyanobacteria able to do that significantly changed Earth's atmosphere?
They carried out photosynthesis and released oxygen.
Name two supercontinents mentioned in the material studied, other than Pangea.
Rodinia and Pannotia.
What happened during the extinction approximately 440 million years ago?
Major climatic and ocean-temperature changes contributed to a mass extinction, causing many organisms to disappear.
How did debris from the asteroid impact contribute to the extinction event?
Atmospheric debris blocked sunlight, disrupted environmental conditions, and contributed to major climatic changes.
According to the hypothesis studied in class, how did the Moon form?
A collision between early Earth and Theia ejected material into orbit, and gravity brought that material together.
Explain the relationship between the development of photosynthesis, the decrease in atmospheric carbon dioxide, and Earth's early glaciation.
Oxygen-producing photosynthesis contributed to changes in atmospheric composition, including a decrease in carbon dioxide. The reduced greenhouse effect contributed to global cooling and extensive glaciation.
What does the existence of several supercontinents tell us about Earth's continents?
Continents have moved, assembled into large landmasses, and separated over geological time.
Which mass extinction is known as the Great Dying, and approximately when did it occur?
The greatest mass extinction, approximately 250 million years ago.
Name two important developments in human evolutionary history that occurred before agriculture.
Walking upright, developing tools, and learning to control fire.
Early Earth had intense volcanic activity and frequent asteroid impacts. Explain why these conditions made early Earth very different from the planet we inhabit today.
The surface was extremely hot, liquid oceans had not yet formed, the atmosphere had a different composition, and frequent impacts made the environment highly unstable.
A planet has liquid water, but its atmosphere contains very little oxygen. Could life exist there? Explain your answer using Earth's early history.
Yes. Earth's earliest life appeared before the major accumulation of atmospheric oxygen. Liquid water was important for early life, and oxygen-producing photosynthesis developed later.
Imagine that Earth's continents had never emerged above the oceans. How would this have changed the development of terrestrial ecosystems?
Terrestrial ecosystems could not have developed in the way they did because there would have been no exposed continental land for plants and animals to colonize.
A mass extinction eliminates many species, but some surviving groups later diversify. Explain why this does not mean the extinction directly created the new species.
Extinction changes ecosystems and ecological opportunities. Surviving populations may diversify over generations, but extinction itself does not directly produce new species.
Explain how the development of agriculture approximately 10,000 years ago changed the relationship between humans and their environment.
Humans increasingly produced their own food and established permanent settlements, changing how they used land and natural resources.