Biodiversity and Effect of Human Interaction on Ecosystems

stages of water cycle (5)

• evaporation - heat from Sun causes liquid water to evaporate into water vapour

• transpiration - evaporation of water from surface of leaves

• condensation - water vapour in air condenses back into liquid water

• precipitation - liquid water falls to Earth as rain, snow, hail, etc

• respiration - release of energy from food leading to release of water vapour from animals / plants, eg exhaling, sweat, etc

what is biogas

gaseous waste produced from decomposition of human, animal and agricultrual waste, used for combustion in industry

main constituent of biogas

methane

process that occurs in the digester

slurry (waste) decays anaerobically due to anaerobic bacteria performing anaerobic respiration

why is biogas generator kept sealed (2)

• methane is a major greenhouse gas and would increase global warming if released

• don’t want oxygen enter, as it could kill the anaerobic bacteria, and grow dangerous aerobic bacteria

why is biogas plant built underground

provides insulation and increases temperature, so decay happens faster and methane is produced quicker

advantages of production of biogas (3)

• uses human, animal and agricultural waste

• methane ( a greenhouse gas) used for cooking, heating and electricity

• biogas is renewable and is carbon-neutral

drawbacks of biogas (4)

• crops used for biogas rather than food

• produces hydrogen sulfide, an atmospheric pollutant which can form acid rain

• is smelly

• less land available for food crops

define biodiversity

variety of different species of organisms on Earth, or within an ecosystem

what does high biodiversity mean

increased stability of ecosystem. one species is less likely to rely on a single species for resources and the physical environment it needs.

why are more raw materials being used and more waste being produced (2)

• increasing populations

• higher demand for higher standards of living

define pollution

releasing substances into the environment in amounts that cause harmful effects and which natural biological processes cannot easily remove

types of pollution (3)

water, land and air

water pollution (3)

• chemicals from industry, eg oil spills

• chemicals used in farming washing into bodies of water

• sewage

land pollution (3)

• toxic farming chemicals used on land, eg pesticides, herbicides

• nuclear waste buried underground

• household waste in landfill sites and it doesn’t break down easily or at all

air pollution (2)

• smoke and acidic gases released into atmosphere

• contributes to acid rain and global warming

oil spills (2)

• unable to be broken down for millions of years

• damages plants and kills marine animals

stages of eutrophication (5)

• excessive nutrients from fertilisers, sewage, etc flushed from land into rivers or lakes by rainwater

• plants flourish as mineral ions absorbed and rapid growth of algae, duckweed and other plants occurs

• algae blooms, blocking sunlight to other plants. other plants don’t photosynthesise, only aerobically respire, so oxygen in water depletes as they die

• bacteria and fungi decompose dead plants and aerobically respire, further depleting oxygen levels of the water

• oxygen levels become so low that fish and other organisms can’t respire aerobically and die, no life is possible. death of the ecosystem

how can rapid eutrophication be prevented

if farmers use organic fertilisers, eg compost, because the organic, nitrogen compounds in manure are less soluble and therefore leached less quickly from the soil by rainwater

landfill as land pollution (3)

• toxic chemicals leak from landfill sites onto land and into water sources

• methane, a major greenhouse gas, is produced

• plastics don’t decay for thousands of years

buried nuclear waste as land pollution (2)

• many materials which don’t readily decompose are buried, eg hazmat suits, and lead-lined containers storing nuclear substances

• slowly releases radioactivity into soil and groundwater

how is acid rain caused (2)

• when atmospheric pollutants, eg carbon dioxide, sulfur dioxide, nitrogen oxides, etc dissolve in rainwater, making it slightly acidic, eg dilute carbonic acids, sulfuric acids and nitric acids

• released by industry / vehicles and reduces pH of rainwater below 5

effects of acid rain (4)

• carbonate materials corroded

• death of conifers

• acidification of soil - reduces soil pH, and leaches mineral ions away from the soil, so stunted growth of trees

• leached mineral ions wash into lakes, rivers and causes eutrophication

what are indicator species

organisms that can survive in certain conditions. if this organism is there, those conditions are met

which species is used as an indicator air pollution levels and why

lichens because they change colour to more orange if sulfur dioxide levels are high

stages of greenhouse effect (4)

• short-wave radiation from the Sun hits Earth

• some energy is absorbed. some radiation re-emitted as longer wave radiation

• some long wave radiation escapes from Earth into space

• some long wave radiation absorbed by layer of greenhouse gases in atmosphere, and re-emitted back to Earth

main greenhouse gases (4)

methane, carbon dioxide, nitrous oxide, and CFCs (chloroflurocarbons)

methane - natural source and human sources (3)

• produced when microbes break down larger organic molecules to release energy

• human sources:

  • decomposition of waste in landfill

  • fermentation of microbes in cattle - more cattle farming, more methane produced

  • fermentation by bacteria in rice paddy fields

carbon dioxide sources (3)

• burning of fossil fuels, eg coal, oil, natural gas

• cement production

• deforestation

nitrous oxide sources (3)

• use of fertilisers

• production of nylon

• burning of fossil fuels in internal combustion engines

CFC sources (2) and reason for decline

• fire extinguishers and fridges

• phased out due to contribution to global warming and harmful effects on ozone layer

why are sea levels rising (2) and impact on organisms

• sea gets warmer and expands. ice on land, eg ice caps and glaciers, is melting

• low-lying habitats are lost to the ocean

define migration

movement of animals to different areas at different times of the year

how does global warming affect migration patterns (3)

• may affect where animals migrate to - eg original area doesn’t have necessary conditions, but another area does

• may affect when animals migrate - eg some areas may be warmer earlier in the year

• may cause some animals to not migrate at all

define distribution of organisms

where they are found within a certain area

global warming effects on distribution of organisms (4)

• organisms adapt to their environment. if abiotic factors change, they maybe can’t survive

• they may migrate to a different area, changing their distribution

• some organisms may become more widely distributed as they can take advantage of new conditions

• some may become less widely distributed as they can’t thrive under new conditions

human uses of land (4)

• building houses and roads

• farming

• quarrying

• landfill / waste

effects of deforestation (6)

• habitat destruction

• loss of biodiversity

• soil erosion

• leaching of mineral ions

• flooding

• can affect whole climate of ecosystem - less transpiration = less rainfall

ways deforestation leads to increased levels of carbon dioxide (4)

• using the land for biofuels which are burnt, releasing carbon dioxide

• trees burnt for energy, releasing carbon dioxide

• dead plant matter decay, and bacteria and fungi release carbon dioxide through aerobic respiration

• less trees means less carbon dioxide can be removed from the atmosphere by photosynthesis

what are peat bogs

plants living in bogs don’t fully decay due to low oxygen and low pH. partially rotted, dead plants build up to form peat (a muddy, clay-like material), a store of all the carbon from those plants.

how is peat contributing to global warming (4)

• peat is cut up and dried to be burnt as fuel

• this releases the carbon in the peat as carbon dioxide

• peat is also sold to gardeners as compost. the peat comes into contact with higher oxygen levels, so microorganisms decompose the peat

• the microorganisms perform aerobic respiration in decay, releasing the carbon in the peat as carbon dioxide

how do humans affect biodiversity through peat bogs (2)

• peat bogs often have drained ditches dug into them so the area can be used as farm land

• increases oxygen in soil, destroys habitat and leads to loss of biodiversity (animals and plants there adapted to low oxygen levels)

ways to increase and maintain biodiversity (5)

• breeding programmes for endangered species

• protection and regeneration of rare habitats

• reintroduction of field margins and hedgerows in agricultural areas, where farmers only grew one type of crop

• reduction in deforestation and carbon dioxide emissions by some governments

• recycling resources rather than dumping waste in landfill

arising conflicts due to biodiversity conservation methods (4)

• economic - protecting biodiversity costs money, eg paying farmers to reintroduce hedgerows

• jobs - local people’s livelihoods lost due to controls, eg fishing quotas to reduce overfishing leads to loss of livelihood of fishermen

• food security - conflict between biodiversity protection and farming, eg killing pests that eat crops reduces biodiversity, and agriculture uses land

• development - building houses, roads, etc affects environment

define food security

having enough food to feed a population

factors threatening food security (5)

• increased birth rates

• as diets change, demand for certain foods increases, which increases scarcity of some foods

• farming affected by new pests and pathogens or changes in environmental conditions, leading to failures and famine

• high input costs of farming, eg seeds, machinery, can make it too expensive to start / maintain food production

• conflicts affect availability of food and water

define sustainability

using resources without affecting the availability of resources for future generations. The use should also protect biodiversity.

ways to improve efficiency of food production from livestock (3)

• limit movement - limits aerobic respiration, so less biomass lost as carbon dioxide through exhaling / water vapour through sweat and exhaling, so faster rate of growth

• constant warm environment - colder temperatures mean livestock must respire aerobically to release heat to warm themselves, which loses biomass as carbon dioxide through exhaling / water vapour through sweat and exhaling. warmer temp means less respiration

• high-protein food fed - lots of biomass fed to them, so they grow large and quickly, as the protein grows and repairs muscle

advantages of intensive farming (3)

• cheaper food

• better standard of living for farmers

• helps feed a growing population

drawbacks of intensive farming (3)

• people think forcing animals to live in unnatural and uncomfortable conditions is cruel

• crowded conditions means rapid spread of diseases so more biomass is infected

• requires lots of energy to maintain warm temperature. means power is used from combustion of fossil fuels, contributing to global warming

why are fish stocks declining (2)

• pollution - pumping toxic chemicals and human waste into rivers, and enters oceans through the water cycle

• overfishing due to high population - catching more fish than nature can replace

how can fish stocks be conserved

using a fish quota - limits number of fish nations can catch, so nature can replace the number caught easily

mycoprotein - source, use, etc (5)

• a protein produced from the fungus Fusarium

• protein used to make high-protein meat substitutes, eg Quorn

• fungus grown in large vats on glucose syrup, a food for the fungus

• fungus supplied with oxygen, ammonia and minerals. kept at a constant pH and temperature so enzymes work fastest at their optimum temperature and pH so lots of mycoprotein is produced quickly

• fungal biomass harvested, purified and dried to make mycoprotein, and then flavourings are added

changes that can cause changes in survival / distribution of species

• temperature increase

• change in soil pH

• increase in carbon dioxide concentration

seasonal changes (2)

• in some regions, temperatures, daylight hours, rainfall, and others will vary dramatically

• some organisms migrate to avoid these changes

geographical changes (2)

• volcanic eruptions and earthquakes alter abiotic factors dramatically

• some organisms die as they aren’t adapted to new conditions and other organisms can colonise the area

negative changes due to human activity (4)

• deforestation - increased carbon dioxide in atmosphere

• eutrophication

• landfill alters soil pH

• bioaccumulation - DDT is persistent, toxic and its concentration rises up the food chain

positive changes due to human activity (4)

• biotechnology

• afforestation

• rare habitats protected

• breeding programmes