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Question 1
A group of students investigated the size of a ladybird population within a woodland. Ladybirds exist as part of a community within the woodland. |
a) | What is meant by a community?
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b) | Describe how the students could use the mark-release-recapture method to estimate the size of the ladybird population.
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c) | Give two conditions that are necessary for the mark-release-recapture results to be valid.
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d) | The students collected 83 ladybirds in their first sample and later collected 98 ladybirds, 14 of which were marked. Use this information to calculate the number of ladybirds in the woodland.
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Question 2
A group of scientists investigated the ecosystem on a sand dune. Ecosystems consist of biotic and abiotic factors. |
a) | What is meant by an abiotic factor?
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b) | Describe how the scientists could determine the average percentage cover for marram grass on a sand dune.
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c) | The sand dune has undergone the process of succession and is now made up of a climax community. Give two features of a climax community.
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d) | Describe and explain how the process of succession occurs.
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Question 3
Some plant species grow on roadside verges and may be sprayed with salt from salt spray applied to the roads in the winter. A student wanted to investigate the distribution of plant species in these areas. |
a) | Describe how they could use a transect to investigate how plant species distribution changes with increased distance from the road.
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b) | Suggest one limitation of using a transect to collect this data.
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c) | The results from the student’s investigation are shown below.
Describe the data shown in the kite diagram above.
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d) | One of plant species X, Y, or Z also grows in coastal ecosystems. Predict which species grows in coastal areas. Explain your answer.
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Question 4
The diagram below shows the changes in the numbers of Arctic hares and lynx from 1988 to 2000. |
a) | Which term is used to describe populations of different species living in the same habitat?
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b) | Describe and explain the changes that occur in the Arctic hare and lynx populations between 1988 and 2000.
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c) | Predation is one example of a biotic factor affecting the size of the Arctic hare population. Give two other examples of biotic factors that may influence their population size.
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Question 5
Warblers are small songbirds found in gardens, woodlands, and marshes. Three species of warbler can often be found in the same tree. Cape may warblers are found at the tips of branches near the top of the tree, bay-breasted warblers are found in the middle part of the tree, and yellow-rumped warblers are found in the lower parts of the tree. |
a) | Suggest one abiotic factor that is likely to affect warblers.
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b) | Suggest and explain one advantage of the warblers occupying different heights of the tree.
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c) | Feather mites are small parasites found on the wing feathers of many birds. These mites feed on the oil that preserves the condition of a bird’s feathers. Birds that are unable to oil their feathers must use more energy to maintain their body temperature. Suggest how feather mites might affect breeding in warblers.
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d) | Feather mites also eat pathogenic bacteria. Explain how this might affect the breeding success of birds.
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Question 6
A conservation group wanted to estimate the population size of leopards in the Samburu national reserve in Kenya. They placed cameras around the reserve which were activated by movement. |
a) | Suggest why the group did not use the mark-release-recapture method to estimate the size of the leopard population.
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b) | The conservation group also used footprints to estimate the size of the population. Suggest two disadvantages of using footprints.
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c) | The group did use mark-release-recapture to estimate the population size of pangolins in the reserve. Explain how.
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d) | Suggest why the mark-release-recapture method may produce unreliable results in large nature reserves.
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Question 7
A group of ecologists studied the growth of algae on a rocky shore. They placed concrete blocks on a rocky shore and recorded the percentage cover of different species at regular intervals. Their results are shown in the table below.
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a) | The ecologists concluded that the process of succession had taken place on the concrete blocks. Explain what is meant by succession.
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b) | Use the information above to name the pioneer species.
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c) | Explain how the data in the table provide evidence of succession.
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d) | Explain why the ecologists measured percentage cover of the algae rather than frequency.
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Question 8
An ecologist studied the population sizes of a species of bird. In this species, young birds leave their nests from June to July and spend the months of August to February feeding in woods and gardens. From March to May a pair of adult birds form a separate territory that they use for breeding. |
a) | Explain why using the mark-release-recapture technique would yield unreliable results during July.
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b) | Explain why using the mark-release-recapture technique would yield unreliable results during April.
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c) | The ecologist carried out the mark-release-recapture method in September. She trapped 34 birds, marked them and released them. Later she collected a second sample in which 16 birds were marked and 23 were not. Use this information to estimate the size of the bird population.
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d) | Some scientists suggest using the base sequences of DNA to estimate the size of populations using mark-release-recapture. Explain how this would work.
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Question 9
Some plants grow in a clustered distribution, whereas others grow in a random distribution. The diagram below shows a clustered and a random distribution.
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a) | Describe how quadrats can be used to investigate whether a plant species has a clustered or random distribution.
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b) | Some plants found in deserts are found in a uniform distribution in which individual plants are widely spaced. Suggest and explain how this distribution provides an advantage to the plants.
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c) | A scientist investigated the populations of black garden ants, Lasius niger, and yellow meadow ants, Lasius flavus. He used the mark-release-recapture method and estimated the population sizes using two different calculations, the Lincoln estimate and the Chapman estimate. Calculate the population sizes of each ant species using the equations below:
Lincoln estimate: population=mn1×n2 Chapman estimate: population=((m+1)(n1+1)×(n2+1))−1 where n = number of individuals in a particular sample and m = number of marked individuals in the second sample.
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d) | Give one difference between the population estimates given by the two equations.
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