Long questions (only 4p and 7p)

Question 1

Outline four ways in which urbanization may influence processes in the hydrological cycle. (4p)

Answer 1

reduced vegetation cover leads to increasing run-off results in flooding

reduced vegetation cover leads infiltration of water into soils thus reduce inputs to groundwater

urbanization can increase heat/local temp leading to greater evaporation

urbanization will increase local water extraction reducing river flows

Question 2

Hydropower is a resource that can be exploited from rivers. Explain how the value of this resource to a society may vary over time.
(7p)

Answer 2

Positive changes promoting the value of hydropower:
rise in environmental awareness/need for renewable energy may increase value of hydropower;

need for industrial development entails increased demand for energy, thus increasing value of hydropower;

improved/more efficient technology of dam building making the political decision more attractive to voters / increasing the margin of profit / reducing the initial investment forLEDCs / making overall project more sustainable;

technological development of small scale/damless projects may render hydropower more aesthetically appealing / cheaper to implement in LEDCs / more environmental-friendly /more fit to ecocentrists;

Negative changes reducing value of hydropower:

impacts of hydropower on aquatic systems / local human settlements cause increasing conflict with cultural values/local needs;

other renewable resources may become more favourable through technological development/reduced costs;

decreasing rainfall/increased evaporation due to climate change renders an existing damless efficient / profitable;

energy security reasons / political change / economic recession dictate shift from hydropower to more dense nuclear power / cheaper coal;

societal values/EVS may stop seeing damming of a river as sustainable and demand shift away from river dams to wind/solar power;

society realizing it was unethical to relocate a local tribe and demanding the restoration of the river;

Question 3

Outline how energy drives the hydrological cycle.
(4p)..

Answer 3

primary source of energy driving hydrological cycle is solar energy;

solar energy causes changes of state in water eg evaporation/sublimation/melting/transpiration;

condensation of water releases (latent) heat energy causing air to rise/hurricanes;

solar energy causes the temperature differences that create winds/cause movement of water vapour in the atmosphere/advection;

kinetic/wind energy moves clouds (from ocean over land, usually);solar energy melts ice producing streams/lakes/rising ocean levels;

solar energy causes both transfers (eg advection) and transformations (eg evaporation) in hydrological cycle;

precipitation/run-off/streamflow occurs due to gravitational energy/difference in potential energy between the high and low positions;

transpiration is driven by opening of leaf stomata which is due to chemical energy (cellular respiration in mitochondria).

Question 4

Explain, with the use of a system diagram, how human activities affect flows in the global water cycle.
(7p)..

Answer 4

melting (1) will increase due to global warming/climate change/increased greenhouse gas emissions;

freezing (2) will decrease due to global warming/climate change/etc;

precipitation (4,6,8) will be polluted due to acid formation/emissions of NOx & SOx/combustion of coal;

precipitation (4,6,8) could change/increase/decrease due to climate change/etc;

percolation/infiltration (8) will decrease due to urbanisation / soil compaction caused by eg overgrazing;

run-off (5) will increase due to urbanization/deforestation;

warmer/polluted streams (5) due to thermal/toxic pollution from industrial effluent;

evaporation (3,7,9) will increase due to global warming/climate change/etc;

evapotranspiration (10) will increase due to global warming/climate change/etc;

evapotranspiration (10) will be reduced due to deforestation;

uptake by plants (11) will be reduced due to deforestation / urbanization / long fallow periods;

groundwater flow/aquifers (12) will change dependent on climatic impacts/precipitation /rate of human extraction;

cloud seeding increases precipitation (4,6,8) (addressing problem of drought/fog around airports).

Question 5

Outline two factors that enable a human population to increase its local carrying capacity (4p) …

Answer 5

range of resources used;
…means that a local human population can consume/exploit more resources available locally than any other species;

human ingenuity/substitution;
…means that humans are capable to find alternative resources when one is near depletion;

variations in lifestyle;
…means that people can be flexible in their mode of consumption of limited/dwindling resources;

importation of resources;
…means that a wealthy population can grow beyond the boundaries set by their local resources;

technological developments; (can be linked to all previous factors)
…allows humans to use available resources more efficiently / discover new resources /import resources from far away

Question 6

Explain how the growth in human population can affect local and regional water resources (7p) …

Answer 6

growing human populations result in increased need for water for domestic/drinking/cooking use;

Commercial development/industrialisation/factories increase water demand;

increasing food demand entails increased irrigation/water for crops/agriculture;

increasing populations may increase poverty and thus economic water scarcity;

areas/locations/countries that have physical water scarcity would be mostly affected;…causing freshwater land resources (lakes, rivers) to dwindle / risking sustainability of freshwater- resources / depletion of aquifers;…often resulting in conflict over access to water;

increased groundwater abstraction may lead to intrusion from salt water;(increased) industrial effluents can cause water (toxic) pollution;

dam construction to meet higher demands of growing population can affect sustainability of that water source;

increasing populations can stimulate technological innovation and greater efficiency of water use / management;

Question 7

Outline the reasons why natural capital has a dynamic nature.
(4p) …-

Answer 7

the value and status of natural capital may vary regionally;
eg cork may be highly valued in areas where grapes for wine are grown;

the value may also vary over time;
eg cork has been used for millennia as bottle stoppers for wine and other products but in the last 20 years its value has decreased as other resources have been used to seal wine bottles;

the value may vary due to other reasons, eg social/political;
eg uranium’s value decreased quickly after the Fukushima nuclear disaster when public pressure led to several countries declaring they would phase out nuclear power;

the value may vary due to environmental/technological reasons;
eg lithium’s value has increased as it is used to make batteries for electric cars and personal devices;

Question 8

Explain how the inequitable distribution of natural resources can lead to conflict.
(7p) …-

Answer 8

natural resources like water/food/productive land/fossil fuel/ore deposits are distributed unequally around the globe/some countries have a lot, some others have few;
eg sub-Saharan African countries face water shortages/Middle East countries have a huge surplus of oil; which may lead one country to invade another for its resources eg ore deposits in Congo/Afghanistan;

inequitabilities may also arise from changes within societies due to overconsumption/population growth/lack of technology(agricultural/extraction/mining)/unsustainable development; …or from changes in their surroundings eg climatic change/international politics/economics/war/embargoes; eg food price crisis in 2008 causing protests/riots/political/economic/social unrest (in both LEDCs & MEDCs);eg water scarcity due to climate change in Syria is argued to be a major cause of civil war in 2011;

Inequitability often leads to conflict when a resource is shared across national borders(usually water storages or oil deposits);eg sharing the Nile’s water resources between Ethiopia, Sudan and Egypt; inequitability in energy/fuel reserves is particularly significant to economics/national security;
eg leading to, and promulgating many conflicts in the Middle East;

conflicts can also occur between constituencies within a country eg social classes/ethnic groups/resentments over government regulations/bans/taxation/private ownerships v public;
eg when cost of clean water is prohibitive for lower social classes;

Question 9

Outline the mechanism of natural selection. (4p) …–

Answer 9

Natural selection occurs through the following mechanism:

a. natural selection acts on the genetic variation of a population;

b. formed by mutations in previous generations;

c. (when environmental conditions change), some individuals will be fitter/more advantageous than others;

d. thus will survive and reproduce at higher rates;

e. inheriting these advantageous traits to their offspring;

f. hence the frequency of that advantageous character will increase in the population;

Question 10

Explain the link between soil fertility, primary productivity and human activity. (7p) …–

Answer 10

soil fertility refers to the ability of soil to support plant growth/primary productivity;

b. This will depend upon the nutrient availability in soils;

c. …and appropriate availability/retention/drainage of water in soils;

d. …and appropriate soil pH/low salinity to allow for plant growth;

e. It will also depend upon appropriate soil texture/aeration/malleability;

f. …and also the community of soil organisms that maintain its nutrient content/condition;

g. human activities may deplete nutrient content through over-irrigation/overcropping/monoculture/overgrazing;

h. human activities may increase salinity through over-irrigation;

i. human activities may increase soil erosion/compaction through tilling/overgrazing/overcropping/land clearance

j. human activities may lower pH through emissions of NOx/SOx/acid precipitation;

k. human activities may reduce soil water through evaporation due to anthropogenic global warming;

l. human activities may improve nutrient content through fertilization/polyculture;

m. human activities may reduce erosion through drip irrigation/terracing/ windbreaks/contour ploughing;

n. human activities may improve soil texture through conditioners/organic fertilizer;

Question 11

Discuss how solid domestic waste disposal options could be used to reduce the threats to marine organisms. (4p) …—

Answer 11

Recycling can reduce plastics entering waterways;
…but is costly/depends on changing lifestyles;

Landfill can reduce wastes entering waterways;
…but can still lead to leaching of toxins into aquatic environments;

Incineration can reduce wastes entering aquatic environments;
…but may cause air pollution and deposition/acidification of marine environments;

Composting can reduce organic waste polluting waterways;
…but is only suitable for biodegradable waste;

Littering laws can reduce waste entering marine systems
…but need appropriate penalties/monitoring etc;

Conclusion e.g. recycling is probably the most reliable protection of marine organisms against plastic waste;

Note: Award [3] max if neither counterarguments nor conclusion are presented I.e. response must include at least one or the other to fullfil the ‘Discuss’ command term.

Question 12

Outline how a positive feedback loop can impact an ecosystem.
(7p) …—

Answer 12

positive feedback loops (destabilizing) amplify changes in an ecosystem;

feedback refers to the return of part of the output from a system as input so as to affect succeeding outputs;

this drives the system towards a tipping point where a new equilibrium is adopted;

this new equilibrium may be an alternative stable state / involve collapse of original system;
eg increased global temperatures are melting permafrost, leading to the release of methane;

…which is a greenhouse gas and leads to further increases in global temperatures;