Chapter 13 - The Earth's atmosphere

Question 1

how long ago was the earth formed?

Answer 1

4.6 billion years ago

Question 2

how do scientists collect data on what the earth was like? 2

Answer 2

gas bubbles trapped in rocks

data gathered from other planets and their moons

Question 3

what was the first phase in the evolution of the atmosphere?

Answer 3

the surface was covered in volcanoes which released gases (CO2 and oxygen)
then nitrogen, water vapour, methane and ammonia were released by volcanoes

Question 4

what gases would the early atmosphere be made from?

Answer 4

mostly carbon dioxide and a little oxygen

Question 5

how were oceans formed? (2 theories)

Answer 5

water vapour in the atmosphere condensed as the planet cooled
icy comets melted and released water

Question 6

what happened to the CO2 in the atmosphere once oceans were formed?

Answer 6

it dissolved into the water and formed carbon precipitates that formed sediments on the sea floor

Question 7

what happened once algae had evolved?

Answer 7

they absorbed the CO2 from the oceans to photosynthesise and produce oxygen as a waste product

Question 8

how are sedimentary rocks formed?

Answer 8

when organisms die, thy sink to the sea bed and are covered in layers of sediment
they then become compressed and form rocks with clear layers

Question 9

what is coal made from?

Answer 9

compressed plant deposits

Question 10

what is crude oil made from?

Answer 10

compressed plankton

Question 11

what is limestone made from?

Answer 11

calcium carbonate deposits from the skeletons of animals

Question 12

what happened once more plants evolved to photosynthesise?

Answer 12

they absorbed much of the CO2 and released more oxygen into the atmosphere
more complex animals could now evolve

Question 13

equation for photosynthesis?

Answer 13

carbon dioxide + water -> glucose + oxygen

Question 14

overall process of the evolving atmosphere

Answer 14

volcanoes produced gases like CO2 and nitrogen
oceans were formed
green plants started to photosynthesise
CO2 was removed and oxygen released
more complex animals could now survive

Question 15

what happens when animals eat plants?

Answer 15

the carbon dioxide in the plant is transferred to the animal’s tissues

Question 16

how was limestone formed?

Answer 16

animals ingested CO2 through plants
they die
build up of skeletons on seabed
pressure of other sediments forms this sedimentary rocj

Question 17

how was coal formed?

Answer 17

plant material, such as ferns, was deposited into swamps

they were buried in anaerobic conditions and compressed for millions of years

Question 18

how were crude oil and natural gas formed?

Answer 18

remains of plankton were deposited into the mud on the seabed
these were covered in sediments
they were compressed
gas and oil are found in this rock

Question 19

what are the main two ways in which CO2 was removed from the atmosphere?

Answer 19

photosynthesising into plants

dissolving in oceans

Question 20

how was methane and ammonia removed from the atmosphere?

Answer 20

they reacted with the oxygen

Question 21

equation for ammonia + oxygen

Answer 21

ammonia + oxygen -> nitrogen and water

Question 22

equation for methane + oxygen

Answer 22

methane + oxygen -> carbon dioxide and water

Question 23

what are the main 4 gases in the current atmosphere?

Answer 23

nitrogen
oxygen
argon
carbon dioxide

Question 24

percentage of nitrogen in atmosphere

Answer 24

78

Question 25

percentage of oxygen in atmosphere

Answer 25

21

Question 26

percentage of argon in atmosphere

Answer 26

0.9

Question 27

percentage of carbon dioxide in atmosphere

Answer 27

0.04

Question 28

evidence against global warming

Answer 28

natural fluctuations in earth temperature (milankowitch cycles)

Question 29

one way of measuring the link between CO2 levels and climate

Answer 29

ice cores are drilled from glaciers which have gases (CO2) inside

Question 30

how does deforestation impact on CO2 levels?

Answer 30

carbon sinks, like rainforests are cut down
less CO2 is removed from air by these trees
CO2 is also released

Question 31

how do rising ocean temperatures affect CO2 levels?

Answer 31

CO2 is less soluble in warm water

oceans less effective carbon sinks

Question 32

3 uses of fossil fuels

Answer 32

electricity
heat homes
fuel cars

Question 33

3 sources of methane

Answer 33

rice fields
cattle
tips

Question 34

why are methane levels rising? 2

Answer 34

increased cattle farming to feed growing population

more rubbish in landfill sites = more methane released by decomposition of waste

Question 35

what is peer reviewing?

Answer 35

where other scientists test hypotheses to make sure they are correct

Question 36

name 3 greenhouse gases

Answer 36

carbon dioxide
methane
water vapour

Question 37

what is the greenhouse effect?

Answer 37

sun emits short length radiation
this passes through the greenhouse gases in the atmosphere
the earth heats up
it emits infrared radiation to cool down
this is absorbed by the gases
re radiated towards earth and heats it up