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41 Cards in this Set
- Front
- Back
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What is an Ecosystem?
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All the organisms living in a particular area and all the non-living conditions. They are dynamic systems changing all the time.
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What is a Biotic factor?
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The living features of an ecosystem.
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What in an abiotic factor?
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The non-living factors of an ecosystem.
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What is a producer?
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An organism that produces complex organic molecules from light/chemical energy.
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What is a consumer?
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An organism that eats other organisms.
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What is a trophic level?
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A stage in a food chain occupied by a particular group of organisms.
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How is energy transfer measured?
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Either by directly measuring amount of energy by burning organisms in a calorimeter or measuring their dry mass (biomass).
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How is energy transfer calculated?
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Calculate the amount of biomass in a sample and multiply by the size of the total population.
The difference in energy between trophic levels is the amount of energy transferred. |
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What is the efficiency of energy transfer?
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Around 90% of energy is lost and 10% is passed through the food chain.
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How is energy lost by producers?
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(60%) Plants can't use all the energy that reaches leaves as it may be of the wrong wavelength or reflected or passes straight through.
Light hits the part of the plant that can't photosynthesise. Some parts aren't eaten by plants as they are indigestible(Cellulose). |
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How is energy lost by consumers?
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30% is lost to the environment when organisms respire and use energy.(respiratory loss)
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What is gross productivity?
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The total energy or nutrients assimilated by an organism, a population, or an entire community.
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How is net productivity calculated?
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Gross productivity - respiratory loss
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How can human activity affect energy transfer?
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Through herbicides, fungicides, insecticides, natural predators, fertilisers and rearing.
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What is succession?
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The process by which an ecosystem changes over time.
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What is the role of pioneer species?
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Species such as sea rocket colonise the sand just above the high water mark.
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Describe the process of succession in the sand dune.
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Wind-blown sand builds up around the plants (mini-dune). As plants die and decay, nutrients accumulate. Plants like sea couch and marram grass colonise and stabilise the soil. With more stability, plants like bird's foot trefoil start to grow. Eventually, the dune areas far inland become grassland, and overtime woodland, allowing much larger plants to grow.
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What is abundance?
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The number of individuals of one species in an area.
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What is distribution?
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Where a species is within the investigation area.
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How is an area sampled using frame quadrats?
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The are placed randomly on the ground. The number individuals of each species are recorded. The percentage cover is measures by counting how much of the quadrat is covered by each species.
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How is an area sampled using point quadrats?
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Placed at random points. Pins are dropped through holes and every plant that the pin touches is recorded. The number of each species is recorded and the percentage cover is measured.
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How is an area sampled using Transects?
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Line transects- a tape measure is placed along the transect and the species that touch the tape measure are recorded.
Belt transects- Data is collected along the transect using frame quadrats placed next to eachother. |
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Describe nitrogen fixation.
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Nitrogen gas is converted to ammonia by Rhizobium found in root nobules of leguminous plants.
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Describe ammonification.
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Nitrogen compounds from dead organisms are turned into ammonium compounds by decomposers.
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Describe Nitrification.
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Ammonium compounds are oxidised into nitrogen compounds:
Nitrosomas- oxidise ammonium into nitrites Nitrobacter- Oxidise nitrites into nitrates. |
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Describe Denitrification.
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Nitrates are converted into nitrogen gas by denitrifying bacteria- they use nitrates in the soil to respire under anaerobic conditions.
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What is the role of decomposers?
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They feed saphrotrophically. Enzymes are secreted onto dead and waste material. The enzymes digest material into small molecules which are absorbed and stored and respired.
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What is carrying capacity?
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The maximum population size that can be maintained over a period of time in a particular habitat.
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Describe Predator-Prey relationships.
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When the predator population increases, more prey are eaten. The prey population gets smaller so there is less food. Fewer predators can survive so the population reduces. This means that the population of the prey can increase and then the predator population so the cycle repeats.
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When does competition occur?
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When resources are not present in adequate amounts to satisfy the needs of all the dependent individuals.
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What is Intrapecific competition?
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Competition between individuals of the same species.
The best adapted individuals survive. If the population size increases, competition increases so the population size decreases so the population remains stable.` |
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What is Interspecific competition?
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Competition between individuals of different species.
It can affect population size and species distribution. |
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What is sustainable management?
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It means that enough resources are taken to meet demands without recording the ability to meet demands in the future.
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How is timber production managed?
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They are cleared in small strips/patches.
The cleared areas aren't too exposed to avoid soil erosion. coppicing- Trees cut close to ground to encourage growth. Only native species are planted and not close together. Posts provide support and grown in tubes. |
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What is conservation?
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The protection and management of ecosystems. It is a dynamic process as methods need to be adapted. It involves how resources are used and replaced and involves reclamation.
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What is preservation?
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The protection of ecosystems, they are kept exactly as they are. Nothing is removed and resources are only used for activities that don't damage them.
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What are the ethical reasons for conservation?
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The belief in the right to exist.
Humans have a moral responsibility. |
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What are the social reasons for conservation?
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Ecosystems are attractive to look at.
Used for activities- bird watching and walking. Without conservation ecosystems would not be available to use them. |
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What are the economic reasons for conservation?
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Ecosystems provide resources that humans need- food, clothes, medicine.
Trade Tourism |
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How has human activity affected the Galapagos Islands?
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Explorers eat species.
Non-native animals are introduced and ate native species. Non-native plants compete with native plants. Fishing has caused a decrease in sea life. An increase in tourism has decreased development and population. |
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