Biology questions and solutions
Browse original practice and official past-paper questions. Each question has its own link, with its source and worked solution.
385 questions · Page 2 of 17
- Q25 · 2025 QCAA · Paper 1 · 5 marksContinuity of life on EarthQUESTION 25 (5 marks) Molecular sequence data from two proteins was used to determine the relatedness of giant pandas, red pandas, polar bears and ferrets. The graph shows the mutation rate of the two proteins used in the investigation. 100 Protein 1 Number of amino acid differences (per 100 residues) 90 80 70 60 50 Protein 2 40 30 20 10 0 0 10 20 30 40 50…
- Q26 · 2025 QCAA · Paper 1 · 7 marksContinuity of life on EarthQUESTION 26 (7 marks) Scientists investigating the impact of ocean temperature on the evolution of marine organisms compiled the data shown. 30 35 25 30 20 Body length (cm) Temperature (°C) 25 15 10 20 5 15 0 Cretaceous Paleogene Neogene 100 80 60 40 20 0 Time (millions of years ago) Key Body length Ocean temperature a) Identi…
- Q1 · 2025 QCAA · Paper 2 · 3 marksContinuity of life on EarthQUESTION 1 (3 marks) a) Define genetic drift. [1 mark] b) Explain why genetic drift is usually high in populations affected by bottlenecks. [2 marks]
- Q2 · 2025 QCAA · Paper 2 · 6 marksGenetics and heredityQUESTION 2 (6 marks) A human karyotype and list of genetic conditions are shown. Genetic condition Common name Monosomy 5 Cri du chat syndrome Monosomy X Turner syndrome Trisomy 13 Patau syndrome Trisomy 21 Down syndrome Trisomy X Triple X syndrome a) Which genetic condition is indicated by the karyotype? [1 mark] b) Explain how errors in meiosis may hav…
- Q3 · 2025 QCAA · Paper 2 · 6 marksBiodiversity and populationsQUESTION 3 (6 marks) Students used 10 quadrats, each 1 m2 in size, to investigate the number of ant nests in a 100 m2 section of their school oval. A random number generator was used to determine the location of each quadrat. Results are shown. Key Quadrat Ant nest 10 m 10 m a) Use the quadrat data to predict the number of ant nests in the 100 m2 section o…
- Q4 · 2025 QCAA · Paper 2 · 3 marksGenetics and heredityQUESTION 4 (3 marks) Explain how transcription factors allow for cell differentiation, using an example.
- Q5 · 2025 QCAA · Paper 2 · 9 marksBiodiversity and populationsQUESTION 5 (9 marks) A student investigating the health of two freshwater ecosystems collected the data shown. Abiotic indicator Healthy range Dissolved oxygen (% saturation) 90–110 Turbidity (NTU) 1–20 pH 6.5–8.0 Ecosystem 1 Ecosystem 2 Abiotic data Dissolved oxygen (% saturation) 95 105 Turbidity (NTU) 20 5 pH 6.2 7.5 Biotic data Species richness 13 12 Si…
- Q6 · 2025 QCAA · Paper 2 · 4 marksFunctioning ecosystems and successionQUESTION 6 (4 marks) a) Explain how energy enters the biotic components of an ecosystem. [2 marks] b) Distinguish between gross primary productivity and net primary productivity. [2 marks]
- Q7 · 2025 QCAA · Paper 2 · 3 marksGenetics and heredityQUESTION 7 (3 marks) The sex of chickens is determined by Z and W chromosomes. Chickens that inherit two Z chromosomes (ZZ) are male, while chickens with one Z chromosome and one W chromosome (ZW) are female. A barred feather pattern is a sex-linked dominant trait inherited on the Z chromosome. A male chicken that was heterozygous for the barred feather pat…
- Q8 · 2025 QCAA · Paper 2 · 2 marksGenetics and heredityQUESTION 8 (2 marks) Distinguish between exons and introns.
- Q9 · 2025 QCAA · Paper 2 · 2 marksContinuity of life on EarthQUESTION 9 (2 marks) Scientists analysed data on three populations (A, B and C) in a region affected by habitat fragmentation. The graphs show how the rate of gene flow and genetic differences between the populations changed over time. Populations A and B Populations A and C High High Rate of gene flow/ Rate of gene flow/ genetic difference genetic differen…
- Q10 · 2025 QCAA · Paper 2 · 10 marksBiodiversity and populationsQUESTION 10 (10 marks) Australian fur seals live in the Southern Ocean and feed on krill. In the 1800s, their population experienced a significant decline due to overharvesting. To monitor their recovery, scientists collected the data shown. 40 000 35 000 30 000 25 000 Number of fur seals 20 000 15 000 10 000 5000 0 1750 1800 1850 1900 1950 2000 Year Fur se…
- Q11 · 2025 QCAA · Paper 2 · 4 marksContinuity of life on EarthQUESTION 11 (4 marks) Mass extinctions occur when the extinction rate of a taxonomic group exceeds the background extinction rate. Mass extinctions are an important part of macroevolution and are often followed by episodes of evolutionary radiation. The graph shows the extinction rate for marine animals alongside the background extinction rate. 20 (families…
- Q1 · 2024 QCAA · Paper 1 · 1 markContinuity of life on EarthQUESTION 1 Which term describes a group of organisms consisting of a common ancestor and all its lineal descendants? (A) clade (B) subgroup (C) population (D) community
- Q2 · 2024 QCAA · Paper 1 · 1 markGenetics and heredityQUESTION 2 Polymerase chain reaction is a technique used in DNA profiling to (A) cut DNA at specific sites. (B) create more copies of DNA. (C) determine the order of nucleotides. (D) separate DNA fragments based on size.
- Q3 · 2024 QCAA · Paper 1 · 1 markGenetics and heredityQUESTION 3 What is a key difference between spermatogenesis and oogenesis? (A) Spermatogenesis produces haploid cells, whereas oogenesis produces diploid cells. (B) Spermatogenesis produces four functional gametes, whereas oogenesis produces one. (C) Spermatogenesis occurs throughout life, whereas oogenesis only occurs after puberty. (D) Spermatogenesis…
- Q4 · 2024 QCAA · Paper 1 · 1 markFunctioning ecosystems and successionQUESTION 4 The table shows data on four plant species. Which is most likely to be a pioneer species? Germination rate Presence of nitrogen-fixing bacteria (A) slow present (B) slow not present (C) rapid present (D) rapid not present
- Q5 · 2024 QCAA · Paper 1 · 1 markBiodiversity and populationsQUESTION 5 A limitation of the biological species concept is that it does not account for species that (A) reproduce asexually. (B) are reproductively isolated. (C) are morphologically indistinguishable. (D) have a different number of chromosomes.
- Q6 · 2024 QCAA · Paper 1 · 1 markContinuity of life on EarthQUESTION 6 What can introduce new alleles into a population? (A) point mutations (B) non-disjunction (C) random fertilisation (D) independent assortment
- Q7 · 2024 QCAA · Paper 1 · 1 markBiodiversity and populationsQUESTION 7 Tolerance ranges for species X and a Holdridge life zone classification chart are shown. 1.0 1.0 0.9 0.9 0.8 0.8 Relative growth rate Relative growth rate 0.7 0.7 0.6 0.6 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0.0 0.0 0 2 4 6 8 10 12 14 16 18 20 22 24 0 50 100 150 200 250 300 350 400 450 500 550 Temperature (°C) Annual precipitation (mm) 0.125 62…
- Q8 · 2024 QCAA · Paper 1 · 1 markBiodiversity and populationsQUESTION 8 In the Linnaean system of classification, two species of the same class will also belong to the same (A) order. (B) genus. (C) family. (D) phylum.
- Q9 · 2024 QCAA · Paper 1 · 1 markFunctioning ecosystems and successionQUESTION 9 The graph shows how populations of two species living in the same area changed over time. Species Y Population Species Z Time Which species interaction is indicated? (A) predation, where species Y preyed on species Z (B) predation, where species Z preyed on species Y (C) competition, where species Y outcompeted species Z (D) competition, where…
- Q10 · 2024 QCAA · Paper 1 · 1 markGenetics and heredityQUESTION 10 A key function of histones is to (A) add nucleotides to a growing DNA strand. (B) bind to specific sections of DNA to initiate replication. (C) allow DNA to tightly condense so it fits into the nucleus. (D) join amino acids to form a polypeptide chain during translation.
- Q11 · 2024 QCAA · Paper 1 · 1 markGenetics and heredityQUESTION 11 Which mode of inheritance leads to continuous variation in the phenotypes of a population due to the cumulative effect of multiple genes? (A) codominance (B) polygenic inheritance (C) incomplete dominance (D) multiple allele inheritance