Origin of Earth's Water and Formation of Earth's Atmosphere

Front

How did the cyanobacteria (which created stromatolites) help to prepare Earth for life?

Back

Stromatolite photosynthesis added large amounts of Oxygen into Earth's atmosphere

Answer explanation

Cyanobacteria, through stromatolite photosynthesis, produced large amounts of oxygen, significantly altering Earth's atmosphere. This oxygenation was crucial for the development of aerobic life forms, preparing Earth for more complex life.

Front

Which gas is 78% of Earth's Atmosphere?

Back

Nitrogen

Answer explanation

Nitrogen makes up about 78% of Earth's atmosphere, making it the most abundant gas. Oxygen, while important, constitutes only about 21%. Ozone and argon are present in much smaller amounts.

Front

Which gas is 21% of Earth's Atmosphere?

Back

Oxygen

Answer explanation

Oxygen makes up about 21% of Earth's atmosphere, making it essential for life. Nitrogen is the most abundant gas at approximately 78%, while ozone and argon are present in much smaller amounts.

Front

Which gas was not present in Earth's first atmosphere?

Back

Oxygen

Answer explanation

Oxygen was not present in Earth's first atmosphere. The early atmosphere was primarily composed of gases like carbon dioxide, nitrogen, and sulfur dioxide, but lacked free oxygen, which developed later through photosynthesis.

Front

Scientists hypothesize that _________ put oxygen into the atmosphere.

Back

photosynthesis by early life (cyanobacteria)

Answer explanation

The correct answer is 'photosynthesis by early life (cyanobacteria)' because these microorganisms were responsible for producing oxygen through photosynthesis, significantly contributing to the oxygenation of Earth's atmosphere.

Front

What element is NOT abundant in the atmospheres of the other planets (because it is only released abundantly on Earth by life)? Options: Carbon Dioxide, Oxygen, Nitrogen, Hydrogen

Back

Oxygen

Answer explanation

Oxygen is not abundant in the atmospheres of other planets because it is primarily produced by life processes on Earth, unlike carbon dioxide, nitrogen, and hydrogen, which are found in various planetary atmospheres.

Front

Why was differentiation of layers possible on early Earth but not today?

Back

Earth was in a molten state

Answer explanation

Differentiation was possible on early Earth because it was in a molten state, allowing denser materials to sink and lighter materials to rise. Today, the Earth is solidified, preventing this process.

Front

Which gas do we NOT observe coming out of modern volcanoes? Options: Nitrogen, Carbon dioxide, Oxygen, Water vapor

Back

Oxygen

Answer explanation

Oxygen is not typically emitted by modern volcanoes. Instead, they primarily release gases like carbon dioxide, water vapor, and nitrogen. Oxygen is a product of photosynthesis and is not a volcanic gas.

Front

Scientist hypothesize that Earth's second atmosphere (after hydrogen and helium were removed) came from:

Back

outgassing by volcanoes

Answer explanation

The Earth's second atmosphere primarily formed from outgassing by volcanoes, releasing gases like water vapor, carbon dioxide, and nitrogen. This process was crucial in creating a stable atmosphere suitable for life.

Front

What is one scientific idea about how water came to Earth?

Back

Much of it was built into the planet from the start

Answer explanation

The correct choice, 'Much of it was built into the planet from the start,' suggests that water was present in the Earth's formation, likely from minerals and compounds that contained water, rather than arriving from external sources.