Classification and Biodiversity (2.1): Eduqas A Level Biology Exam Questions by Topic

EduqasClassification and BiodiversityExam Questions
Written by Tom Whitburn

Topic 2.1 opens Component 2 and is part of the AS course too, so this page mixes A level and AS questions (the AS ones are marked AS). The first half is about how organisms are classified, why the three domains replaced the five kingdoms, how we name species and what counts as evidence that two organisms are related. The second half is biodiversity: what it means, how it changes from place to place and over time, and how you measure it, from a quadrat survey and Simpson's Diversity Index down to the variety of alleles in a gene pool.

The examiners' reports for this topic keep pointing to the same few slips. Students lose a mark for one feature when the question wants two, write a binomial name without a capital letter for the genus, mention "common ancestors" when the mark needs a more recent common ancestor, and forget to round a diversity index to the number of decimal places asked for. Each question below has the mark scheme and a tip from the report so you can see exactly what gained credit.

I don't teach the Eduqas specification myself, so for one-to-one help I recommend Sam. He teaches Eduqas A level Biology at a top-rated sixth form college and is very popular with his students. You can ask about lessons with Sam on WhatsApp using the link at the bottom of this page.

What you need from GCSE

Each question on this page assumes you're secure on these GCSE ideas. If any of them feels shaky, look it up before you start.

  • Living things are sorted into groups: kingdom, phylum, class, order, family, genus and species.
  • A species has a two-part scientific name, the genus followed by the species, e.g. Homo sapiens.
  • Members of a species can breed together to produce fertile offspring.
  • Quadrats and transects are used to estimate how many organisms live in an area.
  • Natural selection: individuals vary, the best adapted survive and breed, and pass on their alleles.

Key terms

These words come up in the questions and mark schemes. Examiners expect you to use them exactly.

  • Domain: the highest group in classification: Archaea, Eubacteria (Bacteria) and Eukaryota.
  • Phylogenetic tree: a branching diagram of evolutionary relationships; the closer two branches join, the more recent their common ancestor.
  • Binomial system: naming a species by genus (capital letter) then species (lower case), giving one name that scientists everywhere use.
  • Species: a group of organisms that can interbreed to produce fertile offspring.
  • Homologous structures: similar structures with different functions, inherited from a common ancestor.
  • Analogous structures: different structures with a similar function, produced by convergent evolution.
  • Species richness: the number of different species in an area.
  • Species evenness: how evenly the individuals are spread across those species.
  • Genetic diversity: the variety of alleles in the gene pool of a population, e.g. the proportion of polymorphic loci.

What these questions cover (Eduqas 2.1)

The questions test these statements from topic 2.1 of the Eduqas A level Biology specification (A400). AS questions (B400) are marked AS.

  • (a) the classification of organisms into groups based on their evolutionary relationships
  • (b) the need for classification and its tentative nature
  • (c) the three domain classification system as compared with the five Kingdom classification system
  • (d) the characteristic features of Kingdoms: Prokaryotae, Protoctista, Plantae, Fungi, Animalia
  • (e) the use of physical features and biochemical methods to assess the relatedness of organisms (including DNA fingerprinting and enzyme studies)
  • (f) the concept of species
  • (g) the use of the binomial system in naming organisms
  • (h) biodiversity as the number and variety of organisms found within a specified geographic region
  • (i) biodiversity varying spatially and over time and affected by many factors
  • (j) biodiversity can be assessed in a habitat (e.g. Simpson's Diversity Index)
  • (k) biodiversity can be assessed within a species at a genetic level by looking at the variety of alleles in the gene pool of a population
  • (l) biodiversity can be assessed at a molecular level using DNA fingerprinting and sequencing
  • (m) biodiversity has been generated through natural selection
  • (n) the different types of adaptations of organisms to their environment including anatomical, physiological and behavioural adaptations

How to use this page

Write your answer on paper before you open the mark scheme. Allow about 1.2 minutes per mark: the 19 questions are worth 42 marks, so about 50 minutes in total. Then mark your answer strictly against the mark scheme and read the examiners' tip underneath it. If you'd rather print the questions, download the PDF pack.

Classification and the domains

Question 1

AS Component 2 · June 2023 · Q1(a)(i) · 1 mark · Easy

Use a Venn diagram of the three domains to state two features shared by all cells.

Venn diagram of the three domains, Eubacteria, Archaea and Eukaryota, with features such as peptidoglycan cell wall, histones, linear DNA and membrane-bound organelles; the question asks for two features in the central region shared by all living organisms.
Show the mark scheme Mark scheme: any two for one mark from DNA or RNA (nucleic acid), plasma membrane, ribosomes, cytoplasm.

Tap an image to open it full size.

From the examiners' report: Read the mark allocation: two features earn the single mark, so one correct feature on its own scores nothing.

Question 2

A level Component 2 · June 2019 · Q1(a)(i) · 3 marks

Explain how modes of nutrition show the evolution of plants, fungi and animals from the Protoctista.

Whittaker's five kingdom diagram showing Prokaryotae, Protoctista, Plantae, Fungi and Animalia with phyla named, and three arrows labelled autotrophic, saprotrophic and holozoic leading from the Protoctista to the three higher kingdoms.
Show the mark scheme Mark scheme: plants are autotrophs, fungi are saprotrophs, animals are holozoic (or descriptions of each), one mark each.

Tap an image to open it full size.

From the examiners' report: Link each kingdom to its own mode of nutrition. Describing autotrophic, saprotrophic and holozoic nutrition without saying which kingdom each belongs to doesn't earn the marks.

Question 3

A level Component 2 · June 2022 · Q1(a)(ii) · 2 marks

Complete the classification of a snail from domain down to species.

Classification table for a snail with Phylum Mollusca, Class Gastropoda, Order Pulmonata and Family Hygromiidae given, and blank rows for domain, kingdom, genus and species.
Show the mark scheme Mark scheme: Domain Eukarya (Eukaryota), Kingdom Animalia, Genus Candidula (capital C), species intersecta (lower case i); four correct for 2 marks, two or three for 1 mark, spelling must be correct.

Tap an image to open it full size.

From the examiners' report: Learn the full hierarchy from domain to species, and copy the genus and species exactly as written in the stem: capital letter for the genus, lower case for the species.

Question 4

A level Component 2 · Autumn 2021 · Q2(c)(ii) · 2 marks

Explain why renaming a bluebell shows that classification is tentative.

Question explaining that Scilla italica was reclassified as Hyacinthoides italica and asking why this shows the tentative nature of classification and why the name may change again.
Show the mark scheme Mark scheme: classification is based on the evidence available and is not fixed, so it may not reflect true evolutionary relatedness (1); it changes as new evidence is found (1).

Tap an image to open it full size.

Naming species

Question 5

AS Component 2 · June 2022 · Q2(b) · 3 marks

Explain the binomial system using a cone snail, and why scientists use it instead of common names.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question referring to Image 2.1 of cone snails with binomial and common names, asking what is meant by the binomial system with reference to organism A and why scientists use it rather than common names.
Show the mark scheme Mark scheme: a two-part name, genus then species (1); Bursa is the genus and nobilis the species, spelt and capitalised correctly (1); common names vary between regions and languages and can cause confusion when identifying species (1).

Tap an image to open it full size.

From the examiners' report: Answer both halves. Saying the binomial name is "international" isn't enough: explain that common names differ between regions or languages, so they cause confusion.

Question 6

AS Component 2 · June 2024 · Q1(a)(ii) · 1 mark

Explain why damselfish living on the same reef are separate species.

Question stating that many related species of damselfish live close together on the same reef and asking why they are classified as separate species.
Show the mark scheme Mark scheme: different species cannot interbreed to produce fertile offspring (or only members of the same species can).

Tap an image to open it full size.

From the examiners' report: Say that they cannot interbreed to produce fertile offspring. Leaving out "fertile" loses the mark.

Evidence for relatedness

Question 7

A level Component 2 · June 2018 · Q3(d)(i) · 1 mark

Explain why comparing amino acid sequences shows evolutionary relationships.

Table of part of the amino acid sequence of cytochrome c from three sources, labelled 1, 2 and 3, from wheat, barley and maize, with the question asking why amino acid sequences show evolutionary relationships.
Show the mark scheme Mark scheme: the more closely related the organisms, the fewer differences in sequence; or the fewer differences, the more recent the common ancestor.

Tap an image to open it full size.

From the examiners' report: Be precise: it's the number of differences in the sequence that matters, and fewer differences mean a more recent common ancestor, not just a common ancestor. Don't drift into vague comments about DNA.

Question 8

A level Component 2 · June 2018 · Q3(d)(iii) · 2 marks · Easy

Use the sequence table and a classification diagram to match each source to maize, wheat or barley.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Table to complete matching maize, wheat and barley to sources 1, 2 and 3, using the cytochrome c sequences and a classification diagram showing wheat and barley in the same tribe.
Show the mark scheme Mark scheme: maize 1, wheat 3, barley 2 (or maize 1, wheat 2, barley 3) for 2 marks.

Tap an image to open it full size.

From the examiners' report: Wheat and barley are the most closely related, so they are the two sources with the fewest differences; maize is the odd one out.

Question 9

AS Component 2 · June 2018 · Q2(c) · 3 marks

Distinguish analogous from homologous structures and explain why analogous features don't show common ancestry.

Question about the pseudo-thumb of red and giant pandas, asking students to distinguish analogous and homologous structures and explain why analogous features are not evidence of common ancestry.
Show the mark scheme Mark scheme: analogous structures are different structures with a similar function (1); homologous structures share a structure from a common ancestor but have different functions (1); analogous structures arise through convergent evolution (1).

Tap an image to open it full size.

From the examiners' report: Most students got the two definitions; the third mark goes to saying that analogous structures arise by convergent evolution.

Question 10

A level Component 2 · June 2024 · Q2(d)(ii) · 3 marks · Easy

Suggest why human/chimpanzee hybrid DNA separates at a higher temperature than human/orangutan DNA.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question describing DNA hybridisation, where single strands from two species form hybrid DNA, and asking why human and chimpanzee hybrid DNA separates at a higher temperature than human and orangutan hybrid DNA.
Show the mark scheme Mark scheme: humans and chimpanzees are more closely related, with a more recent common ancestor (1); their DNA base sequences are more similar, so more bases are complementary (1); so more hydrogen bonds form and must be broken (1).

Tap an image to open it full size.

From the examiners' report: Build a three-step chain: more closely related, so more complementary bases, so more hydrogen bonds to break.

Measuring biodiversity

Question 11

A level Component 2 · June 2025 · Q6(a)(ii) · 1 mark

State the species richness of two sites from a table of quadrat data.

Table 6.1 of the mean number of plants per quadrat for species A to I at two sites, with the question asking for the species richness of each site.
Show the mark scheme Mark scheme: both sites have a species richness of 8.

Tap an image to open it full size.

From the examiners' report: Species richness is simply the number of species present. Don't count a species with a mean of zero at that site.

Question 12

A level Component 2 · June 2025 · Q6(a)(iv) · 2 marks

Work out Site 2's diversity index from Table 6.2 (Site 1 is 0.80), then suggest why species richness alone is not a valid measure of biodiversity here.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question asking students to use their species richness values and diversity index values for the two sites to suggest why species richness alone is not a valid measure of biodiversity.
Show the mark scheme Mark scheme: any two of biodiversity also includes species evenness (1); richness is the same at both sites but the diversity index is different (1); richness doesn't show how abundant or dominant each species is (1).

Tap an image to open it full size.

From the examiners' report: Use your own numbers: the richness is the same at both sites but the index differs, because biodiversity also depends on species evenness.

Question 13

AS Component 2 · June 2019 · Q4(a)(ii) · 4 marks · Hard

Describe a method for collecting data to estimate plant biodiversity on an upland heath.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question about fencing out sheep from an upland heath, asking for a method to collect the data needed to estimate plant biodiversity.
Show the mark scheme Mark scheme: any four from tape measures at right angles as axes of a grid (1); random coordinates from a calculator or computer (1); place the quadrat at the coordinates (1); identify and count each plant species in the quadrat (1); repeat and calculate a mean (1).

Tap an image to open it full size.

From the examiners' report: Full marks went to step-by-step methods: grid, random coordinates, quadrat placed at each coordinate, then each species identified and counted.

Question 14

AS Component 2 · June 2019 · Q4(b)(i) · 3 marks · Easy

Calculate Simpson's Diversity Index for a heath after five years without grazing.

Table of the number of individuals of six plant species immediately after fencing and five years later, with the formula D = 1 minus the sum of n(n-1) over N(N-1) and a working table to complete.
Show the mark scheme Mark scheme: diversity index 0.63 for 3 marks; 0.632 (not rounded) for 2 marks; otherwise 1 mark each for N(N-1) = 8930 and the sum of n(n-1) = 3286.

Tap an image to open it full size.

From the examiners' report: Give the answer to 2 decimal places as asked. Students who left it unrounded were limited to 2 of the 3 marks.

Question 15

AS Component 2 · June 2019 · Q4(c) · 3 marks · Hard

Use plant heights to suggest how more heather cover changed the biodiversity of the site.

Question stating that ground cover by Erica cinerea rose from 33% to 67% after grazing was excluded, and asking how this could have affected biodiversity using the plant heights in the table.
Show the mark scheme Mark scheme: use the heights in the table, e.g. E. cinerea grows to 60 cm but G. saxatile only to 20 cm (1); the taller heather shades smaller plants, which lose the competition for light (1); so some species fall in number or disappear, e.g. Galium saxatile, reducing biodiversity (1).

Tap an image to open it full size.

From the examiners' report: The question tells you to use the data, so quote the plant heights from the table. Answers that ignored the data struggled to score.

Genetic diversity, natural selection and adaptation

Question 16

A level Component 2 · June 2018 · Q5(c)(iii) · 2 marks · Easy

Use DNA sequence data to conclude how a population bottleneck affected northern elephant seals.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question about genetic sequences found in northern elephant seals in the nineteenth century and today, asking for a conclusion about the effect of a population bottleneck on genetic diversity.
Show the mark scheme Mark scheme: the bottleneck decreased genetic diversity (1); only 2 different sequences today compared with 5 in the nineteenth century (1).

Tap an image to open it full size.

From the examiners' report: State the conclusion, then back it up with numbers from the data, such as 2 sequences now against 5 in the nineteenth century.

Question 17

AS Component 2 · June 2025 · Q3(c)(ii) · 1 mark

Explain why a point on a DNA sequence diagram shows when the genus Homo had its highest genetic diversity.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question referring to Image 3.3, showing variation in the DNA base sequences from bones of members of the genus Homo over time, asking why Arrow B marks the time of highest genetic diversity.
Show the mark scheme Mark scheme: it shows the greatest variation in the base sequence.

Tap an image to open it full size.

Question 18

AS Component 2 · June 2024 · Q1(c)(iii) · 3 marks

Suggest how natural selection has affected the biodiversity of damselfish living in closely branched coral.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question about alleles for increased growth being at lower frequencies in damselfish living in corals with small branch spacing, asking how natural selection has affected the biodiversity of these populations.
Show the mark scheme Mark scheme: biodiversity of the population is reduced (1); plus any two of selection against larger fish (1); larger fish can't hide so are more likely to be eaten (1); not enough space for larger fish to survive (1).

Tap an image to open it full size.

From the examiners' report: Stick to this example: one species, with fewer growth alleles where branch spacing is small, so genetic diversity falls. General accounts of natural selection didn't score.

Question 19

AS Component 2 · June 2019 · Q2(c) · 2 marks · Hard

Explain the position and distribution of the algae inside a lichen.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Question with a diagram of a section through a lichen thallus, asking students to explain the position and distribution of the algae within it.
Show the mark scheme Mark scheme: any two of near the upper surface to capture light for photosynthesis (1); the fungal mycelium stops the algae drying out (1); in a thin layer because light doesn't penetrate deeper (1).

Tap an image to open it full size.

From the examiners' report: Explain the distribution as well as the position. Very few students saw that the fungus keeps the algae moist so they don't dry out.

Where students lose marks (from Eduqas examiners' reports and mark schemes)

Each point below is followed by wording that gained marks.

  • Two features earn the one mark: Many students named just one feature shared by all three domains, or a feature shared by only two of them.

    ✔ Gains credit: Any two of "DNA/RNA", "plasma membrane", "ribosomes", "cytoplasm".

  • Capital for the genus, lower case for the species: Binomial names lost marks for wrong spelling or letter case.

    ✔ Gains credit: "Candidula intersecta" and "Bursa nobilis": genus with a capital letter, species in lower case.

  • "International" is only half the reason: Students said the binomial system is an international language but didn't say what goes wrong with common names.

    ✔ Gains credit: "Common names could vary regionally or in different languages, which could cause confusion when identifying species".

  • Interbreed to give fertile offspring: Answers didn't make clear that two species mating cannot produce fertile offspring.

    ✔ Gains credit: "Different species are unable to interbreed to produce fertile offspring".

  • Fewer differences, more recent ancestor: Students made vague references to DNA, or wrote "common ancestor" without saying recent.

    ✔ Gains credit: "The fewer differences, the more recent the common ancestor".

  • Analogous points to convergent evolution: The third mark, why analogous features don't show common ancestry, was the one most students missed.

    ✔ Gains credit: "Analogous structures arise through convergent evolution".

  • Richness is a count of species: Fewer students than expected knew that species richness is just the number of species present.

    ✔ Gains credit: "Both 8": count only the species found at each site.

  • Finish the index: subtract from 1, then round: Some students forgot to subtract from 1 (giving 0.13 in June 2025), and others didn't give 2 decimal places.

    ✔ Gains credit: "Diversity index = 0.63" to 2 decimal places.

Download the questions

Download the PDF pack (19 questions, mark schemes at the end)

Keep practising

Questions, mark schemes and examiners' report extracts © WJEC CBAC Ltd (Eduqas).

Tom Whitburn
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