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23 Cards in this Set
- Front
- Back
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How is carbon released from an animal when it dies? |
Decomposers release CO2 whilst breaking it down or it can fossilise which stores carbon |
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Where can carbon be stored? |
Fossils, deep in the ocean and peat bogs |
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Why is CO2 levels higher at night and in the winter? |
Photosynthesis is an occurring but respiration is which is releasing CO2 There is less light in the day available for photosynthesis and to absorb CO2 |
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What are the two main reasons why CO2 levels are increasing? |
Burning fossil fuels and deforestation which removes large quantities of photosynthesising biomass |
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How can we observe the atmospheric composition from a long time ago? |
Analysing air bubbles in the ice deep in glaciers |
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What is succession? |
The process by which ecosystems change over time as a result of changes in abiotic factors |
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What is primary succession and what are a few examples? |
This occurs on land that has been newly formed for example volcanic rock, creation of new sand dunes by the wind, glaciers retreating exposing rock |
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What is secondary succession? |
This occurs on areas of land where soil is present but contains no plant or animal species for example the ground after a forest fire |
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What are the stages of succession and give examples? |
Pioneer community (lichens) intermediate community (mosses, grass, shrubs) and climax community (woodland) |
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What are the common developments as a result of succession? |
There is a high species diversity the conditions become less hostile and the ecosystem is more stable |
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What are 4 adaptations of Pioneer species? |
Large number of seeds or spores can be produced which germinate rapidly They can photosynthesize They have a high tolerance to extreme environments They can fix nitrogen from the atmosphere so adding to mineral content of soil |
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How is the intermediate community formed? |
When the rocks are broken down and the Pioneer species died and decompose organic products (humus) are released into the soil which can support secondary colonisers e.g. moss thus small animals |
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How is the climax community formed? |
When a few dominant plant and animal species have out competed other species by natural selection so there is usually a reduced biodiversity |
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What is deflected succession? |
When humans halt the natural flow of succession and prevent ecosystems from reaching the climax community |
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What is the plagioclimax? |
The final stage when succession is stopped artificially |
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What is 3 reasons why deflected succession can occur? |
Grazing and trampling of vegetation by animals to prevent the growth of grasslands (this can conserve rare species by preventing dominant species taking hold) Removing existing vegetation to plant crops Burning forests to allow other species to grow |
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Why is marram grass so important for sand dune succession? |
They help bind sand together which holds the structure of the dunes allowing it to act as a wind barrier to allow other plants to grow behind it |
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What are the two ways in which distribution can be measured? |
Belt and line transects which is an example of systematic sampling |
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What is a belt and line transect? |
A line transect involves laying a surveyors tape along the ground and taking samples at regular intervals A belt transect involves laying two parallel lines and taking samples of the area in between them |
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Why are samples used to estimate abundance? |
Measuring the whole population is expensive time consuming and potentially damaging to the organisms |
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How do you perform the capture mark release recapture technique? |
1. Capture many individuals and tag them 2. Release the tagged individuals back into the sample area so they can redistribute 3. recaptcha is many individuals in the sample area and record the number of marked and unmarked individuals |
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How do you estimate the population size using the capture mark release recapture technique? |
(No. in 1st sample X No. in 2nd sample) / No. of recaptured tagged individuals |
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What are 5 disadvantages of using the capture mark release recapture technique? |
Doesn't take into account births deaths immigration or emigration The marker may rub off The might make the organism more visible and vulnerable to predation Animals might not redistribute evenly Dangerous to the organism to be captured |
