Topic 9 - Ecosystems And Material Cycle Flashcards
What is the equation for efficiency of energy transfer between trophic levels?
(Energy transferred to next level ÷ energy available at previous level) X 100
What is eutrophication?
The process by which an aquatic ecosystem becomes enriched.
What is the first stage of eutrophication?
Fertilisers enter the water, adding excess nitrates (more than plants in the water can take in)
What is the second stage of eutrophication?
The excess nitrated cause algae to grow fast and block out sunlight.
What is the third step of eutrophication?
Plants can’t photosynthesise due to lack of light and therefore start to decompose and die.
What is the fourth step of eutrophication?
With more food available, microorganisms that feed on decomposing plants increase in number and use up oxygen in the water.
What is the fifth step of eutrophication?
Organisms that need oxygen for aerobic respiration (e.g. fish) die.
What happens after eutrophication?
Algae die because it has no nutrients. The water loses oxygen (anoxic) so it becomes clear but it’s dead water.
What is a population?
All the organisms of one species in a habitat
What is a community?
All the organisms of different species living in a habitat
What is an ecosystem?
A community of organisms along with the abiotic conditions
What does interdependent mean?
Organisms are interdependent. This means they depend on each other for things like food and shelter in order to survive and reproduce.
What is a disadvantage of interdependence?
A change in the population of one species can have huge knock on effects for other species in the same community
What is mutualism (with an example)?
It’s a relationship between two organisms from which both organisms benefit e.g. bees and flowering plants have a mutualistic relationship. When bees visit flowers to get nectar, pollen is transferred to their bodies. The bees then spread the pollen to other plants when they land on their flowers. The bees get food and the plants get help reproducing
Why are parasites examples of non-mutualistic relationships (with example of parasite)?
Parasites take what they need to survive but the host doesn’t benefit e.g. fleas are parasites of mammals such as dogs. They feed on the host’s blood but don’t offer anything in return
What are environmental changes caused by?
Abiotic and biotic factors which affect communities in many different ways
What abiotic factors affect communities?
Temperature
Amount of water
Light intensity
Levels of pollutants
What biotic factors affect communities?
Competitions
Predation
What is the source of nearly all life on earth?
The Sun
How do plants use light energy?
Plants convert a small % of light energy into glucose. They use some of the glucose immediately in respiration ad store some of the rest as biomass
What is biomass?
The mass of living material that makes up an organism
What happens, in terms of energy transfer, when an animal eats a plant?
it uses some of the energy it gets from the plant and some of the rest is stored in its biomass
How is energy used by organisms?
To stay alive i.e. in respiration, which transfers energy for all life processes, including movement. A lot of energy is transferred to the surroundings by heat. This isn’t stored as biomass so isn’t transferred to the organisms in the next trophic level.
Why doesn’t all of the energy stored as biomass get transferred to the next trophic level?
Not all of the organism is eaten (e.g. the bones) and because not all of the bits that do get eaten can be digested - undigested materials is lost from the food chain in faeces
How can fish farms in areas of open area reduce biodiversity in surrounding areas?
1) Food is added to the nets to ffed the fish, which produce huge amounts of waste. Both the food and the waste can leak into the open water, causing eutrophication
2) Fish farming in open areas often acts as a huge breeding ground for a large number of parasites. These parasites an get out if the farm and infect wild animals, sometimes killing them
3) Predators are attracted to the nets and can become trapped in them and die
4) Sometimes farmed fish can escape into the wild which can cause problems for wild populations of indigenous species
What is a non-indigenous species?
A species that doesn’t occur naturally in an area
Why can non-indigenous species cause problems for indigenous species?
Non-indigenous species compete with indigenous species for resources like food and shelter. Sometimes they’re better at getting these resources and out-comped the indigenous species, which decrease in number and eventually die out. Also non-indigenous species sometimes bring new diseases to a habitat which often infect and kill the indigenous species and therefore reducing biodiversity.
What do conservation schemes help?
They can help to protect biodiversity by preventing species from dying out
Give examples of conservation methods?
- Protecting a species’ natural habitat
- Protecting species in safe areas outside of their natural habitat (e.g. zoos) and introducing captive breeding programmes to increase numbers
- The use of seed banks in order to store and distribute the seeds of rare and endangered plants.
What are the benefits of maintaining biodiversity on a local and global scale?
1) Protecting the human food supply - over-fishing is a problem
2) Ensuring minimal damage to food chains - conserving one species is important to conserving other species in the same food chain
3) Providing future medicines - Plants becoming extinct means we may be missing out on valuable medicines
4) Cultural aspects - for example species may be important to and nation’s/area’s cultural heritage
5) Ecotourism - environmentally-friendly tourism helps bring money into biodiverse area
6) Providing new jobs - e.g. ecotourism, conservation schemes and reforestation schemes
What is ‘food security’?
The world’s population is rising very quickly and it’s not slowing down. This means that global food production must increase too, so that we all have access to enough food that is safe for us and has the right balance of nutrition.
5 factors affecting food security?
- Increasing human population
- Increasing consumption of meat, fish snd increasing animal farming
- Environmental changes caused by human activity
- Sustainability
- New pests and pathogens
How are materials recycled through both biotic and abiotic components of ecosystems?
Living things are made up of elements that they take from the environment e.g. plants take in carbon and oxygen from the air and nitrogen from the soil
They turn these elements into complex compounds (carbohydrate, proteins and fats) that make up living organisms. Elements are passed along food chains when the animals eat the plants and each other
The elements are recycled - waste products and dead organisms are broken down by decomposers (usually microorganisms) and the elements in them are returned to the soil or air, reach to be taken in by new plants and put back into the food chain
Describe the carbon cycle.
Green plants use the carbon from CO2 to make carbohydrates, fats and proteins
Eating passes the carbon compounds in the plant along to animals in a food chain
Both plant and animal respiration while organisms are live release CO2 back into the air
Plants and animals eventually die and decompose, or are killed and turned into useful products
When animals and plants decompose, they’re broken down into microorganisms, such as bacteria and fungi. These decomposers release CO2 back into the air by respiration, as they break down the material
Some useful plant and animal products, e.g. wood and fossil fuels, are burned (combustion). This also releases CO2 back into the air
Decomposition of materials means that their habitats can be maintained for the organisms that live there e.g. nutrients are retuned to the soil
How is water recycled?
Energy from the sun makes water evaporate from the land and sea, turning it into water vapour. (Water vapour also evaporates from plants)
The warm water vapour is carried upwards. When it gets higher up it cools and condenses to form clouds
Water falls from the clouds as precipitation onto land where it provides fresh water for plants and animals
It then drains into the sea and the whole process starts again
What is desalination?
Removing salts from salt water
What is thermal desalination?
Salt water is boiled in a large enclosed vessel, so that the water evaporates. This steam rises to the top of the vessel, but the salt stays at the bottom. The steam then travels down a pipe from the top of the vessel and condenses back into pure water
How can revise osmosis be used as a method of desalination?
1) Salt water is first treated to remove any solids, before being fed at a very high pressure into a vessel containing a partially permeable membrane
2) The pressure causes the water molecules to move in the opposite direction to osmosis - from a higher salt concentration to a lower salt concentration
3) As the water is forced through the membrane, the salts are left behind, removing them from the water
Why does nitrogen in the air have to be turned into mineral ions such as nitrates before being used by plants?
Nitrogen is very unreactive and so it can’t be used directly by plants or animals
Describe the nitrogen cycle.
Plants absorb mineral ions containing nitrogen and use the nitrogen in them to make proteins. Nitrogen is then passed along food chains in the forms of proteins, as animals eat plants and each other.
Decomposers break down proteins in rotting plants and animals, and urea in animal waste. This returns the nitrogen to the soil
What is nitrogen fixation?
The process of turning nitrogen from the air into nitrogen-containing ions in the soil which plants can use.
Describe the two main ways that nitrogen fixation can happen.
Lightning - There’s so much energy in a bolt of lightning that it’s enough to make nitrogen react with oxygen in the air to give nitrates
Nitrogen-fixing bacteria in roots and soil
What are the four types of bacteria involved in decomposition?
- Decomposers
- Nitrifying bacteria
- Nitrogen-fixing bacteria
- Denitrifying bacteria
What do decomposers do?
Decompose proteins and urea and turn them into ammonia
What does nitrifying bacteria do?
Turn ammonia in decaying matter into nitrites and then into nitrates
What does nitrogen-fixing bacteria do?
Turn atmospheric nitrogen into ammonia which forms ammonium ions
What does denitrifying bacteria do?
Turn nitrates back into nitrogen gas. This is of no benefit to living organisms and are often found in waterlogged soils
Which invertebrate animals are indicators of clean water and why?
Invertebrate animals like stonefly larvae and freshwater shrimps are good indicators of water pollution because they’re very sensitive to the concentration of dissolved oxygen in the water. If you find stonefly larvae in a river, it indicates that the water is clean
Which invertebrate species are adapted to living in polluted conditions?
Bloodworms and sludge-worms indicate a very high level of water pollution
What can air pollution be monitored by and why?
By looking at particular types of lichen that are sensitive to the concentration of sulphur dioxide in the atmosphere. The number and type of lichen at a particular location will indicate how clean the air is
What amount and type of lichen indicates clean ear?
Lots of lichen - especially bushy lichen, which need cleaner air than crusty lichen
Where is blackspot fungus found and what does it indicate?
It’s found on rose leaves and indicates clean air as it is sensitive to the level of sulphur dioxide in the air
What ways can you use indicator species to measure pollution?
1) Do a simple survey to see if indicator species are present or absent from an area - is quick but doesn’t tell you how polluted an area is
2) Counting the number of times an indicator species occurs in an area - given a numerical value so you can compare the levels of pollution amongst different places
Advantages and disadvantages of suing indicator species?
Simple and cos-effective
Doesn’t give accurate figures for exactly how much pollution is present. There may also be factors other than pollution playing a role in the presence or absence of a species in an environment
Examples of non-living indicators.
Dissolved oxygen meters and chemical tests are used to accurately measure the concentration of dissolved oxygen in water to show how the level of water pollution is changing
Electronic meters and various laboratory tests are also used to accurately measure the concentration of sulphur dioxide in air to show how air pollution is changing
What is most decomposition done by?
Microorganisms like soil bacteria and fungi (known as decomposers)
What does the rate of decomposition depend on?
Temperature
Water content
Oxygen availability
How does temperature effect the rate of decomposition?
A warm temperature speeds up the rate of enzyme-controlled reactions in microbes, so decay happens faster. Enzymes denature if temperatures get too hot
How does water content effect the rate of decomposition?
Decay takes place faster in moist environments because the organisms involved in decay need water to survive and carry out biological processes
How does oxygen availability effect the rate of decomposition?
Rate of decomposition happens faster when there is plenty of oxygen available. Many microorganism need oxygen for aerobic respiration. Some decomposers don’t need oxygen to respire, but these decomposers work slower anyway
Examples of preservation methods that slow down decomposition.
- Storing food in a fridge or freezer lowers the temperature of the food. This slows down the decomposers’ rate of reproduction (or stops it all together in the case of freezing)
- Storing food in airtight cans stops microorganisms from getting in. Once the food is in, the cans are sealed and sterilised (by exposing then to a high pressure and temperature) to kill any microorganisms present
- Drying food removes the water that microorganisms need to survive and reproduced as does adding salt or sugar, which causes the microorganisms to lose water by osmosis
