Earth & Atmosphere

Question 1

The early atmosphere

Answer 1

Mainly carbon dioxide with smaller amounts of water vapour and other gases.

Question 2

The oceans and the early atmosphere

Answer 2

4 billion years ago, the earth cooled down. This caused water vapour in the atmosphere to condense to liquid water, which formed oceans

Question 3

Oxygen in the early atmosphere

Answer 3

There is evidence to support the idea that it contained little or no oxygen

Question 4

The changing atmosphere

Answer 4

Over hundreds of millions of years, the amount of oxygen increased and carbon dioxide levels decreases.

Question 5

The oceans role in changing the atmosphere

Answer 5

As the earth cooled, water vapor condensed and formed oxygen. The carbon dioxide dissolved in the oceans. Sea creatures used the carbon dioxide to form shells made of calcium carbonate.

Question 6

Oxygens role in changing the atmosphere

Answer 6

Organisms use photosynthesis to make food. These organisms used up carbon dioxide and formed oxygen.

Question 7

The atmosphere today

Answer 7

Nitrogen and oxygen are the main gases in the modern atmoshosphere

Question 8

Greenhouse effect

Answer 8

The greenhouse effect helps keep the Earth warm enough for living organisms to exist

Question 9

What are the greenhouse gases

Answer 9

• Carbon dioxide (burning fossil fuels)
• Methane (livestock farming)
• Water vapour (evaporation from the oceans)