Lesson 4.3.1

4.3.1 Classification, the species concept and the three domains Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

In partnership with Revision Ninja

Lesson 4.3.1, Classification, the species concept and the three domains: 20 multiple choice questions for the Pearson Edexcel Biology A (Salters-Nuffield) (9BI0), Unit 4: Biodiversity and Natural Resources, written with Revision Ninja.

Host it live on the board and students join with a game code on their own devices, or revise alone with Free Play. The answers are revealed in the game.

Host this setFree Play

The 20 questions

  1. Under the biological species concept, what defines a species?

    • Organisms that look alike and share a common habitat
    • Organisms able to interbreed to produce fertile offspring
    • Organisms that share exactly the same genotype at every locus
    • Organisms that descend from a single common ancestor one generation back

  2. Which sequence shows the taxonomic hierarchy in the correct order from broadest to most specific?

    • Kingdom, domain, class, phylum, family, order, genus, species
    • Domain, kingdom, phylum, class, order, family, genus, species
    • Domain, kingdom, order, phylum, class, genus, family, species
    • Domain, phylum, kingdom, order, class, family, species, genus

  3. What are the three domains of life based on molecular phylogeny?

    • Bacteria, Archaea and Eukaryota
    • Prokaryota, Eukaryota and Viruses
    • Archaea, Plantae and Animalia
    • Bacteria, Fungi and Protoctista

  4. Which evidence is used to group organisms into the three domains?

    • The typical habitat in which each organism is most often found
    • Molecular phylogeny based on genetic sequences such as ribosomal RNA
    • The number of cells in the adult body of each organism
    • The colour of the outer covering of each organism

  5. In binomial nomenclature, the two parts of a scientific name are:

    • Family, then genus
    • Species, then family
    • Kingdom, then phylum
    • Genus, then species

  6. Why is critical evaluation of new data by the scientific community important for classification?

    • It can lead to new taxonomic groupings when new evidence changes the picture
    • It removes the need for peer review of new taxonomic data
    • It fixes the classification permanently so that names never change
    • It means that only morphology may be used as evidence for grouping

  7. Which of these is a basis for classification as stated in the specification?

    • Differences and similarities in genotypes and phenotypes
    • The time of day the organism is most active
    • The distance the organism travels in a single day
    • The colour of the sky above the organism's habitat

  8. Two organisms look similar, but a DNA comparison shows they are distantly related. Which statement is best?

    • The two organisms must be the same species because they look alike
    • Phenotypic similarity shows close relationship, so the DNA result must be wrong
    • Convergent evolution can make unrelated species look alike
    • The DNA result proves the organisms belong to the same genus

  9. Two bird populations live apart and cannot interbreed in the wild, but when brought together they produce sterile hybrids. Under the biological species concept, they are:

    • Subspecies within the same genus and family
    • The same species, because they share a common ancestor
    • Different species, because they fail to produce fertile offspring
    • A single species that is only geographically separated

  10. Which organism belongs to the domain Archaea?

    • Methanococcus, a methane-producing microorganism
    • Saccharomyces cerevisiae, a yeast
    • Homo sapiens, a human
    • Escherichia coli, a common gut bacterium

  11. Which organism is a eukaryote?

    • An oak tree, Quercus robur
    • Escherichia coli, a bacterium
    • Bacillus subtilis, a bacterium
    • Methanococcus, an archaeon

  12. Which correctly shows a binomial name written in the accepted format?

    • P. leo lion
    • Panthera-leo species
    • Panthera leo
    • Leo panthera

  13. Organisms A and B are in the same genus but different species. Organisms B and C are in the same family but different genera. Which pair is more closely related?

    • A and B, because they share a genus
    • B and C, because they share a family
    • All three are equally related
    • A and C, because they share only a kingdom

  14. A cell has no nucleus, no membrane-bound organelles and a circular DNA loop in the cytoplasm. Which domain is most likely?

    • Bacteria or Archaea
    • Eukaryota only, with membrane-bound nuclei
    • Plantae, a kingdom of plants
    • Animalia, all multicellular animal life

  15. Scientists sequence the same gene in 20 species and build a tree. Two groups placed far apart by appearance cluster closely together. What is the best explanation?

    • Random mutation has made all the sequences unrelated
    • The tree proves the species are identical in every respect
    • Sequence similarity can reveal ancestry hidden by appearance
    • Morphology is always more reliable than sequence data, so the tree is ignored

  16. Which statement shows a limit of the biological species concept?

    • It ignores all phenotypic differences between organisms
    • It requires DNA sequencing for every case without exception
    • It always gives a clear answer for every species
    • It cannot be applied to asexual organisms

  17. Why does classification based on molecular phylogeny sometimes give a different grouping from one based only on observed phenotype?

    • Appearance can be shaped by environment and convergence
    • All organisms within a domain have identical phenotypes
    • Molecular phylogeny only measures differences in body size
    • Molecular data cannot show evolutionary relationships at all

  18. An organism is moved from one genus to another after new analysis. What change is most likely to follow in its name?

    • Only its species name changes, while the genus name stays the same
    • Its domain changes, so it has no scientific name
    • Its name changes to a number rather than words
    • Its binomial name changes because the genus part changes

  19. Organisms X and Y share 90% of their DNA, while Y and Z share 60%. Which relationship is best supported?

    • All three share exactly the same ancestor one generation back
    • X and Y are more closely related to each other than either is to Z
    • X and Z are genetically identical
    • Z is more closely related to X than Y is

  20. Fossils cannot be tested for interbreeding. How are they usually assigned to a species or genus?

    • By inferring from morphology or molecular evidence
    • By testing whether they could interbreed with living organisms
    • Fossils cannot be assigned to any taxonomic rank at all
    • Fossils are always the same species as their nearest living relatives

All Pearson Edexcel Biology A (Salters-Nuffield) quizzes