C13.1 - History of our atmosphere

Question 1

When do scientists think the Earth was formed?

Answer 1

Scientists think that the Earth was formed 4.6 billon years ago

Question 2

What do scientists think the Earth was, to begin with?

Answer 2

To begin with, scientists think that the Earth was a molten ball of:

1. Rock
2. Minerals

Question 3

What was the Earth for its 1st billion years?

Answer 3

The Earth for its 1st billion years was a very hot, turbulent place

Question 4

Scientists think that the Earth was formed 4.6 billon years ago.
To begin with, scientists think that the Earth was a molten ball of rock and minerals.
The Earth for its 1st billion years was a very hot, turbulent place.
What was the Earth’s surface covered with?

Answer 4

The Earth’s surface was covered with volcanoes that erupted

Question 5

Scientists think that the Earth was formed 4.6 billon years ago.
To begin with, scientists think that the Earth was a molten ball of rock and minerals.
The Earth for its 1st billion years was a very hot, turbulent place.
The Earth’s surface was covered with volcanoes that erupted, releasing fire and gases into the atmosphere.
What did the volcanoes do?

Answer 5

The volcanoes moved chemicals from inside the Earth to the:

1. Surface
2. Newly forming atmosphere

Question 6

Atmosphere

Answer 6

The atmosphere is the relatively thin layer of gases that surround planet Earth

Question 7

What are there several theories about?

Answer 7

There are several theories about the Earth’s early atmosphere

Question 8

There are several theories about the Earth’s early atmosphere, but what is there?

Answer 8

There are several theories about the Earth’s early atmosphere, but there is little direct evidence to draw on from billions of years ago

Question 9

There are several theories about the Earth’s early atmosphere, although there is little direct evidence to draw on from billions of years ago.
However, what have scientists done?

Answer 9

Scientists have reconstructed what they think the atmosphere must have been like

Question 10

There are several theories about the Earth’s early atmosphere, although there is little direct evidence to draw on from billions of years ago.
However, scientists have reconstructed what they think the atmosphere must have been like.
What have scientists reconstructed what they think the atmosphere must have been like based on?

Answer 10

Scientists have reconstructed what they think the atmosphere must have been like, based on:

1. Evidence from gas bubbles trapped in ancient rocks
2. Data gathered from the atmospheres of other planets and their moons in the solar system

Question 11

How can scientists get information about what the Earth’s atmosphere was like in the past based on evidence from gas bubbles trapped in ancient rocks?

Answer 11

Scientists can get information about what the Earth’s atmosphere was like in the past based on evidence from gas bubbles trapped in ancient rocks from Antarctic ice cores

Question 12

What does one theory about the atmosphere suggest?

Answer 12

One theory about the atmosphere suggests that volcanoes released:
1. Carbon dioxide
2. Water vapour
2. Nitrogen
and that these gases formed the early atmosphere

Question 13

How did the first oceans form?

Answer 13

The first oceans formed as water vapour in the atmosphere:

1. Condensed as the Earth gradually cooled down
2. Fell as rain

Question 14

The first oceans formed as water vapour in the atmosphere condensed as the Earth gradually cooled down and fell as rain.
Water collected in hollows in the crust as the rock solidified.
Another theory speculates that what could also have brought water to the Earth?

Answer 14

Another theory speculates that comets could also have brought water to the Earth

Question 15

As the Earth began to stabilise, what was the early atmosphere probably mainly?

Answer 15

As the Earth began to stabilise, the early atmosphere was probably mainly carbon dioxide

Question 16

Chemical formula for carbon dioxide

Answer 16

The chemical formula for carbon dioxide is CO2

Question 17

Chemical formula for water vapour

Answer 17

The chemical formula for water vapour is H20

Question 18

Chemical formula for nitrogen gas

Answer 18

The chemical formula for nitrogen gas is N2

Question 19

Chemical formula for methane

Answer 19

The chemical formula for methane is CH4

Question 20

Chemical formula for ammonia

Answer 20

The chemical formula for ammonia is NH3

Question 21

What does an atmosphere mostly made up of carbon dioxide, with possibly some water vapour, nitrogen gas, traces of methane and ammonia and virtually no oxygen resemble?

Answer 21

An atmosphere mostly made up of carbon dioxide, with possibly some water vapour, nitrogen gas, traces of methane and ammonia and virtually no oxygen resembles the atmospheres that are known to exist today on the planets:

1. Mars
2. Venus

Question 22

After the initial violent years of the history of the Earth, how did the atmosphere remain?

Answer 22

After the initial violent years of the history of the Earth, the atmosphere remained quite stable

Question 23

After the initial violent years of the history of the Earth the atmosphere remained quite stable.
When was this until?

Answer 23

This was until life first appeared on Earth

Question 24

What are there also many theories about?

Answer 24

There are also many theories as to how life was formed on Earth

Question 25

When do scientists think that life began?

Answer 25

Scientists think that life began 3.4 billion years ago

Question 26

Scientists think that life began 3.4 billion years ago, when the first simple organisms, similar to bacteria, appeared. What could these simple organisms use as a source of energy?

Answer 26

These simple organisms could use the breakdown of chemicals as a source of energy

Question 27

Scientists think that life began 3.4 billion years ago, when the first simple organisms, similar to bacteria, appeared. Then, about 2.7 billion years ago, what evolved?

Answer 27

Then, about 2.7 billion years ago: 1. Bacteria 2. Other simple organisms evolved

Question 28

Scientists think that life began 3.4 billion years ago, when the first simple organisms, similar to bacteria, appeared. These simple organisms could use the breakdown of chemicals as a source of energy. Then, about 2.7 billion years ago, bacteria and other simple organisms, such as algae, evolved. What could algae use to make their own food by photosynthesis?

Answer 28

Algae could use the energy from the Sun to make their own food by photosynthesis

Question 29

Algae could use the energy from the Sun to make their own food by photosynthesis. What did this produce as a waste product?

Answer 29

This produced oxygen gas as a waste product

Question 30

About 2.7 billion years ago, bacteria and other simple organisms, such as algae, evolved. Algae could use the energy from the Sun to make their own food by photosynthesis. This produced oxygen gas as a waste product. What happened over the next billions years or so?

Answer 30

Over the next billion years or so, the levels of oxygen rose steadily

Question 31

About 2.7 billion years ago, bacteria and other simple organisms, such as algae, evolved. Algae could use the energy from the Sun to make their own food by photosynthesis. This produced oxygen gas as a waste product. Over the next billion years or so, the levels of oxygen rose steadily. Over the next billion years or so, the levels of oxygen rose steadily, as what?

Answer 31

Over the next billion years or so, the levels of oxygen rose steadily, as the: 1. Algae 2. Bacteria thrived in the seas

Question 32

About 2.7 billion years ago, bacteria and other simple organisms, such as algae, evolved. Algae could use the energy from the Sun to make their own food by photosynthesis. This produced oxygen gas as a waste product. Over the next billion years or so, the levels of oxygen rose steadily, as the algae and bacteria thrived in the seas. Then, what happened?

Answer 32

Then: 1. More 2. More plants evolved

Question 33

About 2.7 billion years ago, bacteria and other simple organisms, such as algae, evolved. Algae could use the energy from the Sun to make their own food by photosynthesis. This produced oxygen gas as a waste product. Over the next billion years or so, the levels of oxygen rose steadily, as the algae and bacteria thrived in the seas. Then, more and more plants evolved. What were all of them doing?

Answer 33

All of them were photosynthesising

Question 34

The chemical formula for photosynthesis

Answer 34

The chemical formula for photosynthesis is: (energy from sunlight) 6CO2 + 6H20 ---> C6H12O6 + 6O2

Question 35

What did plants do, as they evolved?

Answer 35

As they evolved, plants successfully colonised most of the surface of the Earth

Question 36

As they evolved, plants successfully colonised most of the surface of the Earth, so what?

Answer 36

As they evolved, plants successfully colonised most of the surface of the Earth, so the atmosphere became richer in oxygen

Question 37

As they evolved, plants successfully colonised most of the surface of the Earth, so the atmosphere became richer in oxygen. What did this make possible?

Answer 37

This made it possible for the first animal forms to evolve

Question 38

As they evolved, plants successfully colonised most of the surface of the Earth, so the atmosphere became richer in oxygen. This made it possible for the first animal forms to evolve. What could these animals do?

Answer 38

These animals could not make their own food like the: 1. Algae 2. Plants could

Question 39

As they evolved, plants successfully colonised most of the surface of the Earth, so the atmosphere became richer in oxygen. This made it possible for the first animal forms to evolve. These animals could not make their own food like the algae and plants could. What did they rely on?

Answer 39

These animals relied on: 1. The algae and plants for their food 2. Oxygen to respire

Question 40

Where did some of the first photosynthesising bacteria probably live?

Answer 40

Some of the first photosynthesising bacteria probably lived in colonies like stromatolites

Question 41

Many of the earliest living microorganisms could not do what?

Answer 41

Many of the earliest living microorganisms could not tolerate a high oxygen concentration

Question 42

Why could many of the earliest living microorganisms not tolerate a high oxygen concentration?

Answer 42

Many of the earliest living microorganisms could not tolerate a high oxygen concentration, because they had evolved without it

Question 43

Many of the earliest living microorganisms could not tolerate a high oxygen concentration, because they had evolved without it. What happened as a result?

Answer 43

As a result, they largely died out

Question 44

Some bacteria do not need what?

Answer 44

Some bacteria do not need oxygen

Question 45

Some bacteria do not need oxygen and they will die if they are exposed to it. However, where can they survive and breed?

Answer 45

They can survive and breed in: 1. Rotting tissue 2. Other places where there is no oxygen

Question 46

Scientists think that the Earth was formed 4.6 billon years ago. To begin with, scientists think that the Earth was a molten ball of rock and minerals. The Earth for its 1st billion years was a very hot, turbulent place. The Earth's surface was covered with volcanoes that erupted, releasing what into the atmosphere?

Answer 46

The Earth's surface was covered with volcanoes that erupted, releasing: 1. Fire 2. Gases into the atmosphere

Question 47

Scientists can get information about what the Earth's atmosphere was like in the past based on evidence from gas bubbles trapped in ancient rocks from Antarctic ice cores. Each year what forms with tiny bubbles of air trapped in it?

Answer 47

Each year a layer of ice forms with tiny bubbles of air trapped in it

Question 48

Scientists can get information about what the Earth's atmosphere was like in the past based on evidence from gas bubbles trapped in ancient rocks from Antarctic ice cores. Each year a layer of ice forms with tiny bubbles of air trapped in it. What happens the deeper you go in the ice?

Answer 48

The deeper you go in the ice, the older the air

Question 49

Scientists can get information about what the Earth's atmosphere was like in the past based on evidence from gas bubbles trapped in ancient rocks from Antarctic ice cores. Each year a layer of ice forms with tiny bubbles of air trapped in it. The deeper you go in the ice, the older the air. So analysing bubbles from different layers shows you what?

Answer 49

Analysing bubbles from different layers shows you how the atmosphere has changed

Question 50

The first oceans formed as water vapour in the atmosphere condensed as the Earth gradually cooled down and fell as rain. Water did what as the rock solidified?

Answer 50

Water collected in hollows in the crust as the rock solidified

Question 51

The first oceans formed as water vapour in the atmosphere condensed as the Earth gradually cooled down and fell as rain. Water collected in hollows in the crust as the rock solidified. Another theory speculates that comets could also have brought water to the Earth. What happened as icy comets rained down on the surface of the Earth?

Answer 51

As icy comets rained down on the surface of the Earth, they melted

Question 52

The first oceans formed as water vapour in the atmosphere condensed as the Earth gradually cooled down and fell as rain. Water collected in hollows in the crust as the rock solidified. Another theory speculates that comets could also have brought water to the Earth. As icy comets rained down on the surface of the Earth, they melted, doing what?

Answer 52

As icy comets rained down on the surface of the Earth, they melted, adding to its water supplies

Question 53

As the Earth began to stabilise, the early atmosphere was probably mainly carbon dioxide. There could also have been some what?

Answer 53

There could also have been some: 1. Water vapour 2. Nitrogen gas 3. Traces of methane 4. Ammonia

Question 54

As the Earth began to stabilise, the early atmosphere was probably mainly carbon dioxide. There could also have been some water vapour, nitrogen gas, traces of methane and ammonia. There would have been very little or no what at that time?

Answer 54

``` There would have been: 1. Very little Or, 2. No oxygen at that time ```

Question 55

Scientists think that life began 3.4 billion years ago, when what?

Answer 55

Scientists think that life began 3.4 billion years ago, when the first simple organisms, similar to bacteria, appeared

Question 56

Scientists think that life began 3.4 billion years ago, when the first simple organisms, similar to bacteria, appeared. Then, about 2.7 billion years ago, bacteria and other simple organisms, such as what, evolved?

Answer 56

``` Scientists think that life began 3.4 billion years ago, when the first simple organisms, similar to bacteria, appeared. Then, about 2.7 billion years ago: 1. Bacteria 2. Other simple organisms, such as algae ,evolved ```

Question 57

About 2.7 billion years ago, bacteria and other simple organisms, such as algae, evolved. Algae could use the energy from the Sun to make their own food by photosynthesis. This produced oxygen gas as a waste product. Over the next billion years or so, the levels of oxygen rose steadily, as the algae and bacteria thrived in the seas. Then, more and more plants evolved. All of them were photosynthesising, doing what?

Answer 57

All of them were photosynthesising: 1. Removing carbon dioxide 2. Making oxygen

Question 58

Some of the first photosynthesising bacteria probably lived in colonies like stromatolites. They grew in what?

Answer 58

They grew in water

Question 59

Some of the first photosynthesising bacteria probably lived in colonies like stromatolites. They grew in water and did what?

Answer 59

They: 1. Grew in water 2. Released oxygen into the early atmosphere

Question 60

Many of the earliest living microorganisms could not tolerate a high oxygen concentration, because they had evolved without it. As a result, why did they largely die out?

Answer 60

As a result, they largely died out, because there were fewer places where they could survive

Question 61

Some bacteria do not need oxygen and they will what if they are what?

Answer 61

Some bacteria: 1. Do not need oxygen 2. Will die if they are exposed to it