Biodiversity and its measurement: Edexcel International A Level Biology questions

Every Edexcel International A Level Biology exam question on Biodiversity and its measurement (specification points 4.15–4.18), 2019–2025, with its mark scheme and examiner’s report.

All 68 questions on Biodiversity and its measurement, as a list

June 2025, AS Unit 2, Q3(b)(iii) (1 mark): The heterozygosity index is a way of measuring the genetic diversity in a population. Write an equation for the heterozygosity index. (1)
June 2025, Unit 4, Q1(b) (1 mark): Which term describes the species of lizards found only on Redonda? (1) A Archaea B endemic C epigenetic D sustainable
June 2025, Unit 4, Q1(c) (2 marks): Suggest how the rats and goats destroyed the wildlife. Use the information in the photographs to support your answer. (2)
June 2025, Unit 4, Q1(d) (3 marks): Describe how to determine the biodiversity of Redonda to show the effectiveness of the conservation project. (3)
January 2025, AS Unit 2, Q8(a)(i) (2 marks): Suggest why the population of the St Helena plover decreased after the introduction of cats and rats to the island. (2)
January 2025, AS Unit 2, Q8(c)(i) (3 marks): An index of diversity (D) is calculated using the formula: D = N(N 1 ) n(n 1 ) Calculate the index of diversity for habitat 1. Use the table and formula to help
January 2025, AS Unit 2, Q8(c)(ii) (1 mark): Habitat 2 has an index of diversity (D) of 2.80 A student concluded that the second habitat had a higher biodiversity. State whether you agree or disagree with
January 2025, Unit 4, Q6(e)(i) (2 marks): Describe two conclusions that can be made about the effects of these three antibiotics on the species richness of gut flora. (2)
October 2024, AS Unit 2, Q2(b) (3 marks): It is predicted that diatom populations will decrease in number due to global warming. Scientists have suggested that this will cause a decrease in ocean biodiv
October 2024, AS Unit 2, Q3(a) (1 mark): This plant is endemic to Indonesia. State what is meant by the term endemic. (1)
October 2024, AS Unit 2, Q5(a)(i) (2 marks): This species of tree is endangered. Identify two reasons why this species of tree is endangered. Use the information above and the photographs to support your a
October 2024, AS Unit 2, Q8(b) (1 mark): A scientist calculated the heterozygosity index of a population of 5 457 Akhal-Teke horses to be 0.661. How many of these horses are heterozygotes? (1) A 1 850
June 2024, AS Unit 2, Q7(b)(i) (1 mark): Scientists wanted to determine the heterozygosity index of the Malayan tapir species. Which equation can be used to calculate the heterozygosity index? (1) Equa
June 2024, AS Unit 2, Q7(c)(i) (1 mark): Give one similarity between the current and earlier distribution of the Malayan tapir. (1)
June 2024, AS Unit 2, Q7(c)(ii) (1 mark): One difference is that the distribution has reduced due to human activity. Suggest one reason why human activity has caused this change in distribution. (1)
June 2024, AS Unit 2, Q8(c)(i) (3 marks): An index of diversity (D) is calculated using the formula: ( ) D = N N 1 − ( ) ∑ − n n 1 Calculate the index of diversity for habitat two. Use the table and the
June 2024, AS Unit 2, Q8(c)(ii) (1 mark): State which habitat has the higher biodiversity. Give a reason for your answer. (1)
January 2024, AS Unit 2, Q3(a)(ii) (1 mark): The heterozygosity index for a cluster of 8 000 Monarch butterflies was calculated as 0.166. Calculate the number of heterozygotes in this cluster. (1) Answer
January 2024, AS Unit 2, Q3(b) (3 marks): Female Monarch butterflies lay fertilised eggs on the leaves of milkweed plants. Herbicides can be used by farmers to kill plants such as milkweed. Farmers in t
January 2024, AS Unit 2, Q5(b)(i) (1 mark): State what is meant by species richness. (1)
January 2024, AS Unit 2, Q5(b)(ii) (3 marks): The number of individuals of different species in this area of the lake was measured before the appearance of the New Zealand pygmy weed. The table shows these
January 2024, AS Unit 2, Q5(b)(iii) (2 marks): A year after the appearance of the New Zealand pygmy weed in this lake the index of diversity (D) was found to be 1.8. Suggest the effect of the New Zealand pyg
January 2024, AS Unit 2, Q8(a)(i) (1 mark): Which of the following is a term used to describe the fact that this subspecies of island fox is found only on Santa Cruz? (1) A diversity B endemic C mutation
June 2023, AS Unit 2, Q5(a)(i) (1 mark): Which of the following is a term used to describe the fact that this fish is found only in Lake Tanganyika? (1) A diversity B endemic C homozygous D specific
June 2023, AS Unit 2, Q8(b) (3 marks): Snow leopards are found in several areas in Asia. The map shows the areas where snow leopards can be found. Key Areas in which snow leopards are found Russia Ka
June 2023, AS Unit 2, Q8(c)(i) (2 marks): Calculate the percentage decrease in snow leopards from 2002 to 2022. Give your answer to one decimal place. (2) %
June 2023, AS Unit 2, Q8(c)(ii) (1 mark): Suggest one reason for this decrease in the number of snow leopards. (1)
January 2023, Unit 4, Q7(b)(i) (1 mark): State the meaning of the term endemic, as used in the context of this question. (1)
January 2023, Unit 4, Q7(b)(ii) (1 mark): Give one reason why habitat fragmentation could endanger these birds. (1)
October 2022, AS Unit 2, Q7(a) (1 mark): State what is meant by the term species richness. (1)
October 2022, AS Unit 2, Q7(b) (6 marks): Lake Nicaragua and Lake Managua are great lakes. Crater lakes were formed from the craters of volcanoes. The photographs show a great lake and a crater lake in
October 2022, AS Unit 2, Q7(c) (4 marks): A study compared the diversity of cichlid species in two crater lakes. The index of diversity (D) for Lake Xiloá was 2.8. The table shows the data obtained from
June 2022, AS Unit 2, Q5(a)(i) (1 mark): The Hawaii palila honeycreeper is found only in the mountainous forest on one island. Which of the following is the term used to describe this distribution? (1)
June 2022, AS Unit 2, Q5(a)(ii) (2 marks): In 2003, it was estimated that there were 7100 Hawaii palila honeycreeper birds on this island. In 2020, it was estimated that there were 950 of these birds. Ca
June 2022, AS Unit 2, Q8(a) (3 marks): Wolves were introduced into Yellowstone National Park in 1995. Wolves are predators of elk. Before the introduction of wolves, elk grazed undisturbed, eating al
June 2022, AS Unit 2, Q8(b) (3 marks): The photograph shows a beaver. (Source: © Ian MacNicol/Getty Images) The graph shows the mean beaver lifespan in areas with different numbers of elk per km2. 80
June 2022, AS Unit 2, Q8(c)(i) (2 marks): Suggest what information the scientists would need to collect in order to calculate species richness in a habitat in Yellowstone National Park. (2)
June 2022, AS Unit 2, Q8(c)(ii) (1 mark): Write a formula that could be used to determine the biodiversity of a habitat in Yellowstone National Park. (1)
June 2022, AS Unit 2, Q8(d) (6 marks): Beavers and elk eat the shoots of young trees. Beavers use older trees to build dams in the rivers, which create new habitats, such as ponds. Beavers live in co
January 2022, AS Unit 2, Q7(a) (1 mark): Sumatra is described as having a high species richness. State what is meant by the term species richness. (1)
January 2022, AS Unit 2, Q7(c)(i) (1 mark): The heterozygosity index can be calculated using an equation. Write this equation. (1)
January 2022, AS Unit 2, Q7(c)(ii) (1 mark): The heterozygosity index of the 500 titan arum plants in botanical gardens was found to be 0.166. Calculate the number of heterozygotes in this population. (1)
January 2022, AS Unit 2, Q9(a) (1 mark): Which of the following is a term that would be used to describe the fact that this species of giant tortoise is found only on the Galapagos Islands? (1) A diver
January 2022, Unit 4, Q1(d) (3 marks): Climate change is resulting in habitat fragmentation. Habitat fragmentation causes groups of polar bears to become separated from one another. Explain the effec
January 2022, Unit 4, Q7(b)(iii) (1 mark): Estimate the effect of food production on the ratio of biodiversity of mammals. (1) Answer
October 2021, AS Unit 2, Q5(a) (3 marks): This species of tree is endangered and the export of wood from these trees is forbidden from some countries. Suggest three reasons why this species of tree is e
October 2021, Unit 4, Q6(a) (2 marks): State the meaning of the term biodiversity. (2)
June 2021, AS Unit 2, Q7(a) (3 marks): The population of Santa Cruz increases by approximately 6.4% per year. The majority of the population, 85%, live in urban areas. The population of Santa Cruz li
June 2021, AS Unit 2, Q7(b) (1 mark): Non‑endemic species have been introduced to the Galapagos Islands. The graph shows the number of tourists to all the islands and the number of recorded non‑ende
June 2021, AS Unit 2, Q7(c)(i) (3 marks): Calculate the index of diversity (D) for this area of the forest using the formula N(N − 1) D = Σ − n(n 1) Use the table to help you. Give your answer to one de
June 2021, AS Unit 2, Q7(c)(ii) (5 marks): Explain why the spread of the wild blackberry affects the biodiversity of the island. (5)
June 2021, AS Unit 3, Q2(a)(ii) (2 marks): State what is meant by the term biodiversity. (2)
June 2021, Unit 4, Q1(a)(ii) (1 mark): What is the percentage increase in the number of species of moss between the fields cut regularly and the fields not cut? (1) A 23.3 B 70.0 C 233.3 D 333.3
January 2021, AS Unit 2, Q8(a) (3 marks): Suggest how human activity could cause the extinction of the Sehuencas water frog in the wild. (3)
January 2021, AS Unit 2, Q8(b) (4 marks): In 2008, there was only one Sehuencas water frog in captivity. In 2018, five Sehuencas water frogs were discovered in a Bolivian mountain forest. Three of these
January 2021, AS Unit 2, Q8(c) (2 marks): One way of studying the genetic diversity within a species is to calculate the heterozygosity index. Describe how the scientists could calculate the heterozygos
October 2020, AS Unit 2, Q8(a)(ii) (2 marks): It has been predicted that the population will continue to decline by 5.3% per year. Calculate the predicted albatross population after one year. (2) Answer
January 2020, AS Unit 2, Q5(a)(i) (1 mark): State what is meant by the term endemic with reference to this kingfisher. (1)
January 2020, AS Unit 2, Q8(a)(i) (1 mark): The biodiversity of this area of Bhitarkanika National Park could be measured by calculating species richness. Which of the following describes species richness
January 2020, AS Unit 2, Q8(a)(ii) (2 marks): Describe one other way in which the biodiversity of this area of Bhitarkanika National Park could be measured. (2)
January 2020, AS Unit 2, Q8(b) (3 marks): Saltwater crocodiles are found in the rivers in this area. The numbers of this endangered species have decreased over the past 40 years. Explain the possible ca
January 2020, Unit 4, Q4(a)(i) (3 marks): From 2000 to 2012, Malaysia lost 14.4% of its rainforest. This is equivalent to 47 278 km2. Calculate the area of Malaysia covered by rainforest in 2000. Give y
January 2020, Unit 4, Q4(a)(ii) (2 marks): A decrease in the area covered by rainforest results in both a decrease in biodiversity and a decrease in populations. Explain why a decrease in the area covere
June 2019, AS Unit 2, Q2(b) (4 marks): Explain the relationship between the concentration of herbicide and the mean number of species of insects in the three fields. Use the information in the graph
June 2019, AS Unit 2, Q6(a)(i) (1 mark): Which of the following can be used to calculate genetic diversity? (1) A Hardy–Weinberg equation B heterozygosity index C index of diversity D mitotic index
June 2019, AS Unit 2, Q6(a)(ii) (2 marks): Give two differences between genetic diversity and species richness. (2) 1 2
June 2019, AS Unit 2, Q6(c)(ii) (4 marks): Banana plants can reproduce asexually. Most of the bananas grown by farmers around the world are clones from a single parent banana plant called ‘The Cavendish’
June 2019, AS Unit 2, Q8(a) (4 marks): Explain how the reintroduction of beavers resulted in a change in the biodiversity in Scotland. (4)

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