1.2

Question 1

What happened during the first billion years of the earth’s existence?

Answer 1

There was intense volcanic activity

Question 2

What did volcanic activity release

Answer 2

The gases that formed the early atmosphere and the water vapour that condensed to form the oceans

Question 3

During first period of earth,some theories suggest….

Answer 3

Earth’s atmosphere was mainly carbon dioxide
Little or no oxygen gas
•also water vapour and small amounts of Methane,ammonia and hydrogen gas

Question 4

How plants and algae produced the oxygen now in the atmosphere by Photosynthesis

Answer 4

As water vapour cooled, the 1st oceans formed. Early plants/algae began to evolve
Early microorganisms used carbon dioxide in the atmosphere for photosynthesis.
•this made oxygen gas

Question 5

How did the atmosphere surrounding the earth allow light energy radiated from the sun to pass through

Answer 5

• most long-wave radiated by earth= escapes into space

* some= absorbed by GG in atmosphere

Question 6

What makes the earth warm enough to live on?

Answer 6

• GG trap energy in the atmosphere
• energy reaches earth from the sun by short-wave and ultra violet radiation
• the earth warms up and releases energy into space as infrared (longwave) radiation which is absorbed by GG

Question 7

the earth has changed over time as a result of what?

Answer 7

cooling

Question 8

what does the earth consist of?

Answer 8

mantle
core
crust
surrounded by atmosphere

Question 9

which part of earth are cracked into tectonic plates?

Answer 9

crust and upper part of mantle

Question 10

the convection currents within the mantle cause what?

Answer 10

the movement of tectonic plates

Question 11

movement of tectonic: earthquakes

Answer 11

when plates tend to slide past each other, very strong forces build up between them.
This can make them suddenly slip past each other
causing one

Question 12

movement of tectonic: volcanoes

Answer 12

movement of tectonic plates causes rocks to melt at plate boundaries

Question 13

what has cooling meant?

Answer 13

that the earth can now sustain animal and plant life

Question 14

(early atmosphere theory)

-miller and urey (water vapour , ammonia too)

Answer 14

various organic chemicals essential to life were formed after passing an electrical discharge through such a mixture to simulate UV from sun

Question 15

how do. infection currents in the mantle cause the movement of tectonic plates

Answer 15

• nuclear reactions deep inside the earth heat up the mantle, reducing its density
• this causes hottest parts of mantle to rise up by convection
• these convection currents have cracked the crust into tectonic plates