Topic 9: Ecosystems and Material Cycles Flashcards
What are the three types of nutrients cycle?
Carbon, water and nitrogen cycle
Why are the nutrients cycles important?
Carbon, water and nitrogen are essential to life and there is a fixed amount of nutrients on Earth which must be constantly recycled
How are materials cycle going though the living and non-living components of an ecosystem?
Organisms take in elements from their surroundings, elements converted to complex molecules which become biomass, elements transferred along food chain and elements returned to environment during excretion and decomposition of dead organisms
What are the stages of the carbon cycle?
Photosynthesis plants remove CO2 from the atmosphere, eating passes carbon compounds along the food chain, respiration in plants plants and animals returns CO2 to the atmosphere, organisms die and decompose, decomposers break down dead material and release CO2 via respiration and combustion of materials releases CO2
What are the stages of the water cycle?
Energy from the sun evaporates water from sources, transpiration also releases water vapour, water vapour rises, cools and condenses forming clouds, precipitation occurs, water is absorbed by the soil and taken up by roots, some is used in photosynthesis or becomes part of the plant, entering the food chain, excretion returns water to the soil and surface runoff returns to streams, rivers and eventually the sea
What is potable water?
Drinking water
How can potable water be prepared?
Desalination
What is desalination?
A process that removes salts from saline water
What are two methods of desalination?
Thermal desalination and reverse osmosis
What is thermal desalination?
Salt water is boiled, water evaporates, rises and condenses down a pipe and this separates pure water from salts
What happens is reverse osmosis?
Saline water pumped into a vessel containing a partially permeable membrane at high pressure, high pressure forces water molecules to move from an area of low water concentration to an area of high water concentration and pure water separated from salts
What do plants use to make proteins?
Nitrates
Why can’t nitrogen be used directly by plants to form proteins?
Nitrogen is unreactive
What are the four types of bacteria involved in the nitrogen cycle?
Decomposers, nitrogen-fixing bacteria, nitrifying bacteria and denitrifying bacteria
What is the role of decomposers in the nitrogen cycle?
Break down proteins and urea into ammonia and ammonia dissolves in solution forming ammonium ions
What is the role of nitrogen-fixing bacteria in the nitrogen cycle?
Convert nitrogen gas into ammonia and ammonia dissolves in solution forming ammonium ions
Where are nitrogen-fixing bacteria found?
Soil and root nodules of legumes
What type of relationships is exhibited between nitrogen-fixing bacteria and legumes?
Mutualistic relationship, plants receive ammonium ions from bacteria and bacteria gain sugars from the plants
What is the role of nitrifying bacteria in the nitrogen cycle?
Convert ammonium ions into nitrites and convert nitrites into nitrates
What is the role of denitrifying bacteria in the nitrogen cycle?
Convert nitrates into nitrogen gas
Where are denitrifying bacteria commonly found?
Waterlogged soils
What are the stages of the nitrogen cycle?
Lightning and nitrogen-fixing bacteria convert nitrogen gas to ammonia which dissolves to form ammonium ions, nitrifying bacteria convert ammonium ions to nitrate ions which are taken up by plants and used to build protein, feeding passes nitrogen through the food chain, organisms die and decompose, decomposers break down proteins and urea to form ammonia which dissolves to form ammonium ions and denitrifying bacteria convert nitrates in the soil back into nitrogen gas
How can the amount of nitrate in the soil be increased?
Using fertiliser and crop rotation replenishes nitrates that may have been depleted by the previous crop
What is decomposition?
The breakdown of dead materials into simpler organic matter
How do decomposers break down dead matter?
Decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules
What factors affect the rate of decomposition?
Oxygen availability, temperature and water content
Why is oxygen required for decomposition?
Most decomposers require oxygen for aerobic respiration
How does the availability of oxygen affect the rate of decomposition?
As oxygen levels increase, the rate of decomposition increases but as oxygen levels decrease, the rate of decomposition decreases
Why can decomposition still occur in the absence of oxygen?
Some decomposers respire anaerobically but the rate is slower and produces less energy
How does temperature affect the rate of decomposition?
Decomposers release enzymes: rate highest at 50C, lower temperatures, enzymes work too slowly, rate decreases and high temperatures, enzymes denature and decomposition stops
How does soil water content affect the rate of decomposition?
Decomposers require water to survive: in moist conditions the rate of decomposition is high and in waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases
What conditions are required to make compost?
Conditions that give a high rate of decomposition: plentiful supply of oxygen, warm and moist
What is the methods of food store used to slow down the rate of decomposition?
Stored in fridge/freezer to slow down the activity of microbes, stored in airtight cans to prevent the entry of microorganisms, high temperatures sterilised cans, destroyed any bacteria, adding salt or sugar kills microbes and food kept dry to reduce the ability of microorganisms to survive
What is an indicator species?
A species whose presence or absence in an environment provides indication of environmental conditions
What indicator species can be used to identify polluted water?
Bloodworms and sludge-worms
What indicator species can be used to identify clean water?
Freshwater shrimps and stonefly
What indicator species can be used to identify clean air?
Black spot fungus found on rose leaves
What are lichens used for?
Used to monitor air pollution
How can lichens indicate air pollution?
Sensitive to the concentration of soulful dioxide, different types of lichens grow in different levels of air pollution, abundance and distribution of lichens indicate levels of pollution
What are the use of indicator species as a measure of pollution?
Cheaper, simpler and used to monitor pollution levels over a long periods of time however less accurate than non-living indicators and don’t provide a definitive figure of pollution levels
What the levels of organisation in an ecosystem?
Individual, population, community and ecosystem
What is population?
All organisms of the same species living with one another in a habitat
What is community?
All of the populations of different species living together in a habitat
What is ecosystem?
The community of organisms and non-living components of an area and their interactions
What does ‘organisms within a community are described as being ‘interdependent’ mean?
Organisms are dependent upon each other and a change in the population of one species can affect other populations within a community
What are some examples of interdependent in a community?
Plants depend on pollination, herbivores are dependent on plants and animals are dependent on mares
What is mutualism?
The interaction between two organisms where both benefit as a result of their relationship
What is the parasitism?
The interaction between two organisms where only one organism, the parasite, benefits whilst the host doesn’t
What are abiotic factors?
The non-living aspects of an ecosystem e.g temperature and light intensity
How does communities are affected by environmental conditions?
Environmental conditions affect the abundance and distribution of organisms within communities
How are communities affected by pollutants?
Toxic chemicals bioaccumulate in food chains to deadly concentrations at higher trophic levels, killing tertiary and quaternary consumers, fertilisers that contaminate water sources can cause eutrophication, killing multiple populations within a community and air pollution can affect the ability of some plant’s species to survive
What are biotic factors?
The living components of an ecosystem e.g competition
How does competition affects communities?
The presence of competitors affects population distribution and size and if one species is better adapted to survive in a certain environment, it will outcompete other species, causing their populations to decline
How does predation affects communities?
predation affects prey populations within a community and population of all other organisms within the food chain will also be affected
What piece of apparatus is used to measure the abundance and distribution of organisms in an area?
Quadrat
Which piece of apparatus is used to study the distribution of organisms across a gradient?
Belt transect
What does a food chain show ?
It describes the feeding relationships between organisms and the resultant stages of biomass transfer
What is biomass?
The total mass of living material
What are trophic levels?
The stages in a food chain
What do arrows in a food chain represent?
The direction of biomass transfer
What is a simple food chain?
Producer -> primary consumer -> secondary consumer-> tertiary consumer
Why are producers the first trophic levels?
Producers provide all biomass for the food chain and the rest of the food chain involves the transfer of this biomass
What does a pyramid of biomass represent?
It represents the dry mass of living material at each trophic level of a food chain
Why is a pyramid of biomass almost always pyramid-shaped?
Producers have the greatest biomass so have the longest bar and as you move along the food chain biomass is lost so the bars decrease in length
Why is biomass lost between each trophic level in a food chain?
Glucose is immediately used for respiration in plant, respiration to generate heat energy for movement, some parts of organisms are indigestible and egestion and excretion
Why are there rarely more than four or five trophic levels in a food chain?
Above this, there is insufficient energy to support another breeding population
What is the equation for calculating the efficiency of biomass transfer between trophic levels?
Biomass available after transfer / biomass available before transfer x 100
What is biodiversity?
The variety of living organisms in an ecosystem
How does fish farming farming affect biodiversity?
Food used to feed the fish and waste can leak into water sources, causing eutrophication, parasites from fish farms may spread and contaminate surrounding ecosystems and other organisms may become tangled in netting
How does the use of fertilisers affect biodiversity ?
Excess fertiliser can wash into water sources causing eutrophication and death of many species so this reduces biodiversity
How can fertilisers cause eutrophication?
Fertilisers run-off into rivers and lakes, nutrients build-up in water, algal bloom blocks sunlight, aquatic plants cannot photosynthesise, less oxygen produced, they die and decompose, decomposers further depleted oxygen levels and animals can no longer respire aerobically so die
How does the introduction of non-indigenous species affect biodiversity?
They may out-compete native species, causing a reduction in population numbers, native species may become the prey of no-indigenous species and they may bring new diseases which could kill large numbers of native species, reducing biodiversity
How can humans more positively impact biodiversity?
Protection of endangered species, conservation schemes, reforestation, sustainable farming and minimising global greenhouse gas production
What is reforestation?
Replanting forests to help restore biodiversity
How do conservation schemes protect biodiversity?
They prevent species from becoming extinct and increase’s populations numbers, maintaining biodiversity
What are the benefits of maintaining biodiversity?
Ensures future food requirements can be met, reduces damage to food chains, increases the likelihood of species adapting to future environmental change, many plant species are yet to be discovered and may contain chemicals that could be used in future medicines, safeguarding valuable future resources, aesthetics and jobs provided by ecotourism, reforestation and conservation schemes
What is food security?
Ensuring that populations have access to adequate amounts of safe and nutritious foods
What are some of the biological factors affecting food security?
Rising human population, changing diets, new pests and pathogens, environmental change and sustainability
How can the rising human population affect food security?
As human population increases, global food production must also increase in order to meet the growing demand for food
How can changing diets affects food security?
Greater consumptions of near and fish in wealthier populations, less energy and biomass available from livestock than crops, livestock use land for grazing and are fed crops that could otherwise be uses for human consumption and less food is available for humans and reduction in food security
How can new pests and pathogens affect food security?
Pests and pathogens can reduce or destroy crop yields, negatively impacting food security
How can sustainability affects food security?
Unsustainable farming methods disrupt food chains, compromising the ability to meet future food requirements, due to the high input costs, many LEDCs cannot maintain modern farming methods and using land for biofuel production reduces land available for crops
How can environmental change due to human activity affects food security?
Emissions of greenhouse gases have been linked to global warming which must affect crop growth and salinisation reduce agricultural potential of soils
