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Question 1
A group of students wanted to investigate the species diversity in a local woodland. |
a) | What is meant by species diversity?
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b) | The students wanted to calculate the index of diversity for the woodland. Give two pieces of data they would need in order to calculate an index of diversity.
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c) | The students took a large number of random samples when investigating the woodland. Explain why it was important for them to take a large number of samples.
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d) | Explain why it was important that their samples were random.
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Question 2
A student investigated the species richness and index of diversity of animal species in the centre of a field and in its surrounding hedges. His results are shown in the table below. |
a) | Calculate the species richness for each habitat.
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b) | Calculate the Simpson's index of diversity for the hedges. Use the following formula: D=1−(Σ(Nn)2) where N = total number of organisms and n = total number of organisms of each species. Give your answer to 1 decimal place.
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c) | The index of diversity was much higher in the hedge than in the centre of the field. Explain why.
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d) | Some farmers are replanting hedges on their farmland. Suggest one advantage and one disadvantage of replanting these hedges.
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Question 3
Bison are large land mammals that were driven out of the United Kingdom by hunting and habitat loss. Recently four bison have arrived in north Kent as part of a rewilding project. Bison increase habitat diversity by knocking down trees, stripping off bark, and making dust baths. |
a) | What is meant by habitat diversity?
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b) | A key benefit of the reintroduction of bison is the predicted increase in habitat diversity. Explain how the knocking down of trees and the stripping of bark increases habitat diversity.
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c) | Suggest one other advantage of reintroducing bison to the United Kingdom.
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d) | Increasing habitat diversity may lead to an increase in both species and genetic diversity. Explain how.
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Question 4
A student investigated how cutting plants in his back garden affected the biodiversity of insects. He created two sample areas, each measuring 3 m x 3 m. He left one sample area untreated and used a lawnmower to cut the plants every fortnight in the other sample area. After 3 months, he collected data on five insect species found in each sample area. The table below shows his results. |
a) | Species richness and an index of diversity can be used to measure biodiversity in an ecosystem. What is the difference between these two measures of biodiversity?
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b) | Calculate the Simpson's index of diversity for the untreated area. Use the following formula. D=1−(Σ(Nn)2) where N = total number of organisms and n = total number of organisms of each species. Give your answer to 2 decimal places.
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c) | Describe and explain the effect of cutting plants on the biodiversity of insects.
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d) | There are ethical and economic arguments for maintaining biodiversity. Give one ethical and one economic argument for maintaining biodiversity.
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Question 5
A group of students investigated the population size of daisies in two different fields. One field included a pathway often used by residents of the town, whereas the other field was undisturbed. |
a) | Describe how the students could estimate the size of the daisy population in each field.
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b) | The students wanted to find out if there was a significant difference between the population size of daisies in the two fields. Name the statistical test they would need to use and explain your choice.
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c) | Give the null hypothesis for this statistical test.
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d) | The students found that the field with the pathway contained fewer daisies. Suggest why.
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Question 6
A group of scientists investigated the biodiversity of butterflies in two different areas over a period of 5 months. They collected butterflies from ten sites in each area every month. Their results are shown in the diagrams below. |
a) | Define species richness.
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b) | One of the scientists used the data above to conclude that the woodland provides a more suitable habitat for the butterflies than the park. Do the data support this conclusion? Explain your answer.
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c) | Give two ways in which the scientists could have improved their method of data collection. For each suggestion, explain why it would lead to improved results.
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d) | One of the scientists wanted to extend the investigation by investigating the link between butterfly numbers and plant distribution in the park. He wanted to find out how the distribution of plants in the park changed with increased distance from the pathway. Describe how the scientist could use a transect to investigate plant distribution.
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Question 7
A scientist counted the number of invertebrate species present in two different rivers, A and B. The figure below shows the scientist’s results. |
a) | Use the graph above to calculate the Simpson's index of diversity for the invertebrates counted in river A. The formula to calculate the Simpson's index of diversity (D ) is D=1−(Σ(Nn)2) where N is the total number of organisms of all species and n is the total number of organisms of each species. Give your answer to 2 significant figures.
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b) | Explain why it is more useful to calculate an index of diversity than to record the species richness.
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c) | Suggest and explain a reason for the difference in numbers of Slate Drake mayfly in each river.
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d) | The scientist also wanted to investigate the diversity of invertebrates in the areas surrounding the rivers. Explain how they could use a pitfall trap to sample invertebrate biodiversity.
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Question 8
A group of scientists investigated the effect of a herbicide on the diversity of insects. They sprayed several fields with the same volume of different concentrations of the same herbicide. After a period of time, they calculated the mean index of diversity for each field. Their results are shown below. |
a) | The scientists placed traps to collect insects at sites chosen at random. Explain why it was important for them to choose the sites randomly.
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b) | The scientists collected insects using a method that was ethical but also allowed them to accurately identify the species of each insect. Suggest one consideration the scientists should have taken into account to make sure their method was ethical.
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c) | Suggest one consideration the scientists should have taken into account to make sure their method allowed accurate identification of each species.
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d) | During their investigation, the scientists sprayed one field with a solution that did not contain any herbicide. Explain why.
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e) | Explain the relationship between herbicide concentration and the index of diversity of insects.
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Question 9
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 10
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 11
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 12
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 13
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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