Name the layers of the Earth that are solid.
The inner core.
Most of the mantle.
What are tectonic plates?
Tectonic plates are massive pieces of the Earth's crust which has cracked. They are constantly moving.
Describe how activity within the Earth results in earthquakes (3 marks).
Earthquakes are caused by sudden movement of tectonic plates (1), the movement is caused by convection currents (1). Convection currents are created by heat released from radioactive decay (1).
What happens at places where the tectonic plates meet?
Earthquakes and volcanoes.
It is difficult to predict accurately when and where earthquakes will happen.
Why were Wegner's ideas about continental drift not accepted for many years?
Other scientists did not accept his ideas mainly because he could not explain why the continents moved/no evidence.
How did the oceans form?
During the first billion years of Earth's life the surface was covered with volcanoes which released CO2, water vapour and nitrogen.
As the Earth cooled most of the water vapour condensed to form oceans.
What produced the oxygen in the atmosphere?
In the next 2 billion years after the formation of oceans; bacteria, algae and plants evolved.
Algae and plants used the CO2 for photosynthesis and released oxygen.
As the number of pants increased as did the amount of oxygen and the CO2 decreased.
What was the Miller-Urey experiment?
Miller and Urey did an experiment based on what scientists thought was in the early atmosphere: mixture of water, methane, ammonia and hydrogen and high voltage spark to simulate lightning.
From this experiment, they found amino acids were produced which are the building blocks for proteins.
In what ways did carbon from carbon dioxide become 'locked up'?
-Plants took up lots of CO2 in photosynthesis. Trees turned to coal.
-Animals ate plants, so much of the carbon ended up in plants and animal remains as sedimentary rocks and fossil fuels.
-Limestone formed from shells and skeletons of marine organisms.
What are the approximate percentages of nitrogen and oxygen in the air?
About 80% nitrogen and 20% oxygen.
Other gases like CO2, water vapour and noble gases make about 1%.
Why can gases in the air be separated using fractional distillation?
Gases in the air can be separated because they have different boiling points.
Name two processes that release CO2 into the atmosphere and two processes that remove it from the atmosphere.
Released to atmosphere-
Removed from atmosphere-
2. Dissolve in oceans.
Describe simply the Earth's structure.
The Earth is made of layers called the core (inner and outer), the mantle and the crust with the atmosphere around the outside.
Why did Miller and Urey use methane, ammonia and hydrogen for the Earth's early atmosphere?
These gases contain the elements in amino acids.