A-Level Biology Topic 18: Classification, Biodiversity and Conservation MCQs – 30 Practice Questions with Answers (Cambridge 9700)
Free practice for Cambridge A-Level Biology 9700 on classification, biodiversity and conservation, with every question followed by a short explanation to help you check your understanding.
Classification
Q1. According to the biological species concept, what defines a species?
- (A) Organisms that look identical in every feature in the population studied, under the conditions described for this investigation
- (B) A group of organisms that can interbreed to produce fertile offspring
- (C) Organisms that occupy exactly the same habitat
- (D) Organisms with the same common name
Show Answer
Answer: B – The biological species concept defines a species as a group that can interbreed and produce fertile offspring.
Q2. According to the morphological species concept, how are species distinguished?
- (A) By whether they can produce fertile offspring together
- (B) By the niche they occupy in an ecosystem
- (C) By their DNA sequence alone, with no other evidence
- (D) By their observable structural features
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Answer: D – The morphological species concept groups organisms by observable features such as shape and structure.
Q3. According to the ecological species concept, what is central to defining a species?
- (A) The niche it occupies, including its habitat, resources and interactions
- (B) The colour of its body in adult life
- (C) The number of offspring it produces each year
- (D) Its position in a food chain on one particular day in the population studied, under the conditions described for this investigation
Show Answer
Answer: A – The ecological species concept defines a species in terms of the niche it occupies.
Q4. Into which three domains are organisms classified?
- (A) Plantae, Animalia and Fungi
- (B) Bacteria, Viruses and Eukarya
- (C) Archaea, Bacteria and Eukarya
- (D) Protoctista, Plantae and Animalia
Show Answer
Answer: C – Organisms are classified into the three domains Archaea, Bacteria and Eukarya.
Q5. Archaea and Bacteria are both prokaryotes, but they differ in which features?
- (A) Only in their size and shape
- (B) Their membrane lipids, ribosomal RNA and cell wall composition
- (C) Only in whether they can cause disease
- (D) Their number of nuclei and mitochondria for the organisms and the conditions described in this investigation
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Answer: B – Archaea and Bacteria differ in membrane lipids, ribosomal RNA and the composition of their cell walls.
Q6. Which sequence gives the taxonomic hierarchy in the Eukarya domain from largest to smallest group?
- (A) Kingdom, phylum, class, order, family, genus, species
- (B) Species, genus, family, order, class, phylum, kingdom
- (C) Kingdom, class, phylum, family, order, genus, species
- (D) Phylum, kingdom, order, class, genus, family, species
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Answer: A – The hierarchy runs kingdom, phylum, class, order, family, genus, species.
Q7. Which description best fits the kingdom Protoctista?
- (A) Prokaryotic organisms with no nucleus
- (B) Multicellular organisms that feed by ingestion
- (C) Organisms with chitin cell walls that feed saprotrophically in the sample studied, across the range of conditions described here
- (D) Eukaryotic organisms, many unicellular, that are not plants, animals or fungi
Show Answer
Answer: D – Protoctista are eukaryotic organisms, many of them unicellular, that do not fit into the plant, animal or fungus kingdoms.
Q8. Which features characterise the kingdom Fungi?
- (A) Cells with chloroplasts that photosynthesise for the organisms and the conditions described in this investigation
- (B) Cells with no walls that ingest food
- (C) Cells with chitin walls that feed saprotrophically or parasitically
- (D) Prokaryotic cells with peptidoglycan walls
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Answer: C – Fungi have chitin cell walls and obtain nutrients saprotrophically or as parasites, rather than by photosynthesis or ingestion.
Q9. Which contrast correctly separates Plantae from Animalia?
- (A) Plants are heterotrophic and animals are autotrophic
- (B) Plants have no cell walls and animals have cellulose walls in the population studied, under the conditions described for this investigation
- (C) Plants have chloroplasts and animals do not, while animals ingest food and plants do not
- (D) Plants are prokaryotic and animals are eukaryotic
Show Answer
Answer: C – Plants are autotrophic with cellulose walls and chloroplasts, while animals are heterotrophic, ingest food and have no cell walls.
Q10. How are viruses classified, in the scheme used at this level?
- (A) By the disease symptoms they cause in humans
- (B) By their size under a light microscope
- (C) By whether they infect plants or animals
- (D) By the type of nucleic acid they contain, RNA or DNA, and whether it is single stranded or double stranded
Show Answer
Answer: D – Virus classification here is limited to the type of nucleic acid, RNA or DNA, and whether it is single stranded or double stranded.
Biodiversity and Sampling
Q11. What is an ecosystem?
- (A) A single species and its predators only
- (B) A community of organisms interacting with each other and with their abiotic environment
- (C) A list of all the species found in one country
- (D) The climate of an area, without its living organisms under the conditions described, for the population in this investigation
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Answer: B – An ecosystem is a community of organisms together with the abiotic factors with which they interact.
Q12. What is meant by the niche of a species?
- (A) The exact place where one individual was found
- (B) The total number of individuals in a population for the organisms and the conditions described in this investigation
- (C) The role and way of life of a species, including its habitat, resources and interactions
- (D) The taxonomic family to which a species belongs
Show Answer
Answer: C – A niche is the role of a species in its ecosystem, covering its habitat, the resources it uses and its interactions with other organisms.
Q13. Biodiversity can be assessed at which levels?
- (A) The number and range of ecosystems and habitats, the number of species and their relative abundance, and genetic variation within each species
- (B) The number of mammals in an area only
- (C) The total mass of plants in an area only
- (D) The average temperature and rainfall of an area only
Show Answer
Answer: A – Biodiversity is assessed at the level of ecosystems and habitats, species number and abundance, and genetic variation within species.
Q14. Why is random sampling important when assessing biodiversity?
- (A) It guarantees that every species will be found
- (B) It makes the survey faster by sampling only one spot
- (C) It ensures that only the commonest species are counted under the conditions described, for the population in this investigation
- (D) It avoids bias, so the sample is representative of the whole area
Show Answer
Answer: D – Random sampling avoids bias from the surveyor choosing convenient or interesting spots, giving a representative sample.
Q15. A frame quadrat is most suitable for which purpose?
- (A) Counting fast-moving birds across a whole woodland
- (B) Tracking the migration of large mammals
- (C) Estimating the distribution and abundance of sessile or slow-moving organisms in a small area
- (D) Measuring the depth of a pond at its centre
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Answer: C – Frame quadrats are used to sample the distribution and abundance of organisms that do not move away, such as plants.
Q16. What is the difference between a line transect and a belt transect?
- (A) A line transect covers a wide strip, while a belt transect records only a thin line
- (B) A line transect records organisms touching a line, while a belt transect records organisms within a strip of set width along the line
- (C) A line transect is used only in water, while a belt transect is used only on land
- (D) A line transect counts mobile animals, while a belt transect counts only soil
Show Answer
Answer: B – Along a line transect, organisms touching the line are recorded; a belt transect samples a strip of known width beside the line.
Q17. In a mark-release-recapture study, 40 animals are marked and released, then 50 are captured later, of which 10 are marked. Using the Lincoln index, what is the estimated population size?
- (A) 200
- (B) 80
- (C) 500
- (D) 20
Show Answer
Answer: A – The Lincoln index gives N = (40 × 50) ÷ 10 = 200.
Q18. Which formula gives Simpson’s index of diversity, D?
- (A) D = Σ(n ÷ N)
- (B) D = 1 + Σ(n ÷ N)²
- (C) D = Σ(n ÷ N)² for any sample
- (D) D = 1 − Σ(n ÷ N)²
Show Answer
Answer: D – Simpson’s index of diversity is D = 1 − Σ(n ÷ N)², where n is the number of individuals of one species and N is the total number of individuals.
Q19. A sample contains two species in equal numbers, 50 of each. What is Simpson’s index of diversity, D, for this sample?
- (A) 0.25
- (B) 0.75
- (C) 0.50
- (D) 1.00
Show Answer
Answer: C – D = 1 − (0.5² + 0.5²) = 1 − 0.50 = 0.50.
Q20. Which correlation test is appropriate for ranked data, or data that are not normally distributed?
- (A) Pearson’s linear correlation, which requires normally distributed data
- (B) Spearman’s rank correlation, which uses ranks rather than raw values
- (C) The t-test, which compares two means
- (D) The Lincoln index, which estimates population size
Show Answer
Answer: B – Spearman’s rank correlation is used when data are ranked or not normally distributed, while Pearson’s linear correlation is used for normally distributed data showing a linear relationship.
Conservation
Q21. How can climate change cause a species to become extinct?
- (A) It shifts temperatures and rainfall beyond the range a species can tolerate, and suitable habitats may disappear
- (B) It always increases the food supply for every species
- (C) It prevents all competition between species
- (D) It stops all hunting by humans at once
Show Answer
Answer: A – Climate change can move conditions outside a species’ tolerance range and remove the habitats it depends on.
Q22. Which human activity is a direct cause of extinction through loss of living space?
- (A) Counting species in a nature reserve in the population studied, under the conditions described for this investigation
- (B) Growing plants in a botanic garden
- (C) Storing seeds in a seed bank
- (D) Degradation and loss of habitats, for example by clearing land
Show Answer
Answer: D – Degradation and loss of habitats remove the places species need to live and breed, which can drive them to extinction.
Q23. Which is a valid reason for maintaining biodiversity?
- (A) It guarantees that no species will ever change
- (B) It removes all competition between species
- (C) It protects ecosystem stability and future sources of food, medicines and other resources
- (D) It allows every habitat to be used for building
Show Answer
Answer: C – Maintaining biodiversity helps keep ecosystems stable and preserves resources that humans and other species may need.
Q24. What role do zoos play in conservation?
- (A) They keep animals only for display, with no breeding
- (B) They support captive breeding, research and education about endangered species
- (C) They release all captive animals into the wild immediately in the population studied, under the conditions described for this investigation
- (D) They replace the need to protect wild habitats
Show Answer
Answer: B – Zoos contribute through captive breeding programmes, research and public education, as part of wider conservation work.
Q25. What is the purpose of a seed bank, and of a frozen zoo?
- (A) To store seeds and genetic material long term, preserving genetic diversity for the future
- (B) To grow food crops for sale in the same year only
- (C) To display rare plants and animals to visitors
- (D) To replace national parks and marine parks
Show Answer
Answer: A – Seed banks store seeds, and frozen zoos store genetic material such as gametes and embryos, preserving diversity for future use.
Q26. What is the main conservation role of national parks and marine parks?
- (A) To allow unrestricted hunting and fishing everywhere in the population studied, under the conditions described for this investigation
- (B) To convert wild land into farmland
- (C) To keep endangered species only in captivity
- (D) To protect habitats and species in the wild, in conserved areas
Show Answer
Answer: D – Conserved areas such as national parks and marine parks protect habitats and the species living in them in situ.
Q27. In IVF as used for endangered mammals, what happens?
- (A) An embryo is transferred without any fertilisation step
- (B) A surrogate mother is used with no embryo involved
- (C) Fertilisation takes place outside the body, and the resulting embryo can then be transferred to a female
- (D) The female is prevented from breeding for life
Show Answer
Answer: C – In IVF, eggs are fertilised outside the body, and the embryo formed can be transferred to a female to develop.
Q28. What is surrogacy in the conservation of endangered mammals?
- (A) Keeping an animal in a zoo for its whole life
- (B) An embryo is carried to term by a surrogate female, which may be of a closely related species
- (C) Freezing an embryo with no plan to use it
- (D) Cloning an adult animal from a single cell
Show Answer
Answer: B – In surrogacy, a surrogate female carries an embryo of an endangered species to term, which can help when the mother cannot carry it herself.
Q29. Why are invasive alien species controlled?
- (A) They can outcompete native species, spread disease and disrupt ecosystems
- (B) They always increase native biodiversity
- (C) They never interact with native species
- (D) They are always harmless outside their native range under the conditions described, for the population in this investigation
Show Answer
Answer: A – Invasive alien species can outcompete natives for resources, introduce disease and damage ecosystems, so controlling them protects native biodiversity.
Q30. What are the roles of the IUCN and CITES in conservation?
- (A) The IUCN sells endangered animals, and CITES breeds them in zoos
- (B) The IUCN builds national parks, and CITES funds seed banks
- (C) The IUCN regulates all farming, and CITES bans all scientific research
- (D) The IUCN assesses the conservation status of species, and CITES regulates international trade in endangered wild species
Show Answer
Answer: D – The International Union for Conservation of Nature assesses threat status, while the Convention on International Trade in Endangered Species regulates trade in listed wild species.
Work through any questions you missed again, then revise those areas before moving on to the next topic.