Topic 1&2 - The Earth: Evolution Of The Atmosphere

Question 1

How were the early atmosphere and the oceans formed?

Answer 1

Volcanic eruptions gave out lots of gases, which formed the early atmosphere of carbon dioxide, water vapour and small amounts of other gases. Some water vapour condensed and formed the oceans.

Question 2

What happened to the carbon dioxide in the early marine organisms after they died?

Answer 2

When marine organisms dies they were buried under layers of sediment. This caused the carbon that was inside them to become locked up in carbonate rocks.

Question 3

How have plants contributed towards the Earth’s current atmosphere?

Answer 3

Plants remove carbon dioxide from the atmosphere and, by photosynthesising, produce oxygen. This has resulted I the current atmosphere consisting of 21% oxygen and only a small amount of carbon dioxide.

Question 4

What was the Earth’s early atmosphere like?

Answer 4

The early atmosphere was probably mostly carbon dioxide. Water vapour and other gases might have been present in small amounts. There was probably virtually no oxygen in the early atmosphere.

Question 5

What are the two most abundant gases in the atmosphere? What are their relative percentages?

Answer 5

Nitrogen (78%) and oxygen (21%).