Atmosphere

Question 1

Photosynthetic organisms evolved about 2700 million years ago.
The composition of the atmosphere slowly changed as a result of the development of photosynthesis. Two main gases changed in concentration.

Name the gas which increased in concentration.(1)

Answer 1

Oxygen/O2/ozone/O3

Question 2

Photosynthetic organisms evolved about 2700 million years ago.
The composition of the atmosphere slowly changed as a result of the development of photosynthesis. Two main gases changed in concentration.

Name the gas which decreased in concentration.(1)

Answer 2

Carbon dioxide/CO2;

Question 3

Mangrove ecosystems are important stores of fixed carbon.
State why this is important for the maintenance of the atmosphere. (1)

Answer 3

Keeps CO2/temperature of atmosphere constant/balanced/equilibrium;
[A correct reference to carbon sequestration/global climate change]

Question 4

Explain the trends of temperature change with altitude in the stratosphere. (2)

Answer 4

absorption of UV/shortwave;
[R heating]

from above/sun
[R closer to the sun]

Question 5

Explain the trends of temperature change with altitude in the troposphere. (2)

Answer 5

absorption of IR/longwave;
[R heating]

from below/earth

Question 6

Describe two negative feedback mechanisms that resist increases in atmospheric temperature. (4)

Answer 6

increased evaporation/cloud cover;
increased albedo/more light reflected/less light absorbed;
AND
increased photosynthesis;
reduced CO2 so less IR absorbed

Question 7

Explain why there is very little water vapour in the stratosphere. (1)

Answer 7

(upper) troposphere/ below the stratosphere is below zero/ very cold;
water vapour condenses/ freezes/ falls as precipitation

Question 8

The relationships between temperature and the processes that control atmospheric carbon dioxide concentrations are complex.

Explain how an increase in temperature may cause an increase in atmospheric carbon dioxide. (1)

Answer 8

increased decomposition/respiration/more forest fires;
melting permafrost

Question 9

The relationships between temperature and the processes that control atmospheric carbon dioxide concentrations are complex.

Explain how an increase in atmospheric carbon dioxide may cause an increase in temperature. (1)

Answer 9

increased absorption of infra-red (IR)

Question 10

Name two greenhouse gases that don’t contain carbon. (1)

Answer 10

2 named GHGs that don’t contain carbon;
tropospheric ozone
NOx/nitrous oxide
water vapour

Question 11

The relationships between temperature and the processes that control atmospheric carbon dioxide concentrations are complex.

Explain why the increase in the atmospheric carbon dioxide concentration since the Industrial Revolution in the 18th Century is much less than may have been expected to be caused by the amount of carbon dioxide released by humans. (2)

Answer 11

removed by named natural processes (in establishing new equilibrium);
dissolved in sea;
absorbed by corals;
absorbed/sequestrated by plants;
forms carbonate rocks

Question 12

Explain how ozone depletion threatens humans through its impact on human health.(2)

Answer 12

DNA mutation;
proteins/enzymes denatured;
sunburn;
skin cancer;
retina damage/ cataracts;
other stated impact

Question 13

Explain how ozone depletion threatens humans through harm caused to other living organisms.(2)

Answer 13

lower crop yield/fishery yields/other stated impact on humans;
reduced photosynthesis;
egg damage;
leaf (cuticle) damage;
reduced photosynthesis/egg damage/other stated impact;
impact stated for humans if not already used

Question 14

Explain the relationship between UVB at ground level and ozone concentration. (3)

Answer 14

inverse relationship;
ozone absorbs UV/ low ozone allows UV transmission;
UV(B) causes chlorine release from CFCs/ODSs;
chlorine causes ozone depletion

Question 15

Explain how the use of one named new material has reduced CFC use. (2)

Answer 15

named application that previously used CFCs;
named alternative material;

e.g.
refrigeration
HCFCs, hydrocarbons, ammonia

grease solvent
alcohols

aerosol propellant for deodorant, hairspray, cleaners
hydrocarbons

foam plastics
HCFCs, HFCs, hydrocarbons, carbon dioxide

Question 16

Describe how the release of chlorofluorocarbons (CFCs) has resulted in ozone depletion. (2)

Answer 16

breakdown (of CFCs) due to UV releases chlorine/
CFC + UV= Cl + remaining CFC/FC;

reaction (of Cl) with monatomic O/reaction (of Cl) with ozone/
Cl +O= ClO/
ClO + O= ClO2/
Cl + O3= ClO + O2;

Question 17

Why is ozone depletion a threat to human health? (2)

Answer 17

UVB/ increased UV/ reaches humans;
mutation/ DNA damage/ skin cancer/ cataracts/ retina damage;

Question 18

Outline how CFC use has been reduced by the introduction of alternative materials. (2)

Answer 18

named alternative material for named use;

e.g.
HCFCs, HFCs
refridgerants

CO2, N2, HCFCs, HCs
foam plastics

butane, propane,hydrocarbons, HFC, HFA
aerosol propellants

Question 19

Outline how CFC use has been reduced by the introduction of alternative processes. (2)

Answer 19

named alternative process for named use;
e.g.
trigger packs, pump action
spray

stick/roll on
deodorant application

Question 20

Suggest why the Montreal Protocol has been more effective at controlling CFC emissions than the Kyoto Protocol has been at controlling greenhouse gas emissions. (2)

Answer 20

ODSs- simpler cause/fewer feedback mechanisms than climate change/ fewer gases;

more evidence/greater public awareness;

greater political agreement/ all major countries signed up (Montreal)/ some countries exempt from Kyoto;

alternatives to CFCs available/ fossil fuels difficult to replace/ fossil fuel combustion basis for development/industrial economies;

Montreal ban on (most) ODSs and Kyoto sets targets for reduction

Question 21

Explain how an increase in the temperature of the atmosphere may cause changes in the survival and distribution of wildlife. (10)

Answer 21

change in named abiotic factor/habitat feature;
e.g.
water temperature
wind velocity
precipitation pattern
nutrient availability
water level

specific impact on wildlife;
e.g.
competition for named resource
habitat loss
displacement of wildlife
rate of colonisation
lack of biological corridor
changes in migration patterns
interspecies relationships

one named taxon illustrating specific impact;