Skill Align QCE Biology - Free Online Pack 0 Paper 2
An independently authored QCE Biology practice paper with worked answers and question-specific marking guidance.
- Paper
- Paper 2 Question and Response Book
- Reading
- 5 minutes perusal
- Writing
- 90 minutes
- Assessment
- 52 marks
A QCAA-approved scientific or graphics calculator may be used. Notes and other unauthorised materials are not permitted.
Short-response questions
Questions 1-11 are short response. Answer all parts, show calculations and justify conclusions with the supplied biological evidence.
Question 1
3 marksA reserve has wet gullies covering 20% of its area and dry slopes covering 80%. A rare orchid may occur in either habitat. Fifty equal-sized quadrats will be allocated in proportion to habitat area and positioned randomly within each habitat.
Question 2
6 marksCassowary signs per kilometre along six equal-effort transects from the forest edge inward are 1, 2, 4, 7, 8 and 8. All transects are in one reserve, and sign persistence and visibility may vary with vegetation density.
Question 3
6 marksThe pedigree shows a hypothetical human trait across three generations. Assume one gene controls the trait, genotypes always produce their expected phenotypes, and no new mutations or environmental effects change the recorded phenotypes. Females are XX and males are XY. Consider only autosomal dominant, autosomal recessive, X-linked dominant and X-linked recessive models. Birth outcomes are independent.
Question 4
3 marksLeaf litter falls onto a rainforest floor and is consumed by detritivores before microorganisms complete decomposition.
Question 5
9 marksA canyon separated one frog population into eastern and western populations. Calls now differ between the populations, experimental crosses produce 22% viable offspring compared with 88% within-population crosses, and conserved DNA sequences differ more between than within populations.
Question 6
4 marksA purple-flowered plant of unknown genotype is crossed with a homozygous recessive white-flowered plant. Offspring are 51 purple and 49 white.
Question 7
3 marksBefore a marine heatwave, allele H had frequency 0.27 in a snail population. Among surviving breeders its frequency was 0.48; 64% of H carriers survived compared with 29% of non-carriers.
Question 8
2 marksA frog is heard on 30% of single night surveys, but repeated surveys show it occupies 60% of wetlands.
Question 9
2 marksA fungus receives carbohydrates from tree roots and increases the roots' access to phosphate.
Question 10
10 marksIndependently replicated aquaria containing equal seagrass biomass are randomly assigned to 20%, 50% or 90% surface light for six weeks and rotated among bench positions. Dissolved nutrients, temperature and salinity are held constant. Mean biomass changes are -18%, +4% and +21%, respectively. The supplied measurements also include photosynthetic oxygen production, respiration, leaf area and final dry biomass.
Question 11
4 marksPCR products from a regulatory locus are cut with an enzyme. Genotype LL gives a 420 bp band, ll gives 260 bp and 160 bp bands, and Ll gives all three bands. A DNA ladder and known LL, Ll and ll samples resolve at their expected positions, while a no-template lane has no band.
Worked Solutions And Marking Guide
General marking principles
- Award each listed mark independently when the required biological evidence is demonstrated.
- Accept scientifically accurate equivalent wording and logically equivalent calculations.
- Do not award an unsupported causal claim where the evidence establishes only an association.
Question 1
(a) - Treat wet gullies and dry slopes as separate strata. - Allocate 10 quadrats randomly within gullies and 40 randomly within slopes in proportion to area. - Use the same quadrat size and search rule so density estimates are comparable.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Treat wet gullies and dry slopes as separate strata.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Allocate 10 quadrats randomly within gullies and 40 randomly within slopes in proportion to area.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Use the same quadrat size and search rule so density estimates are comparable.
Question 2
(a) - Signs increase from 1 near the edge to 8 on the two deepest transects. - The increase levels off between the fifth and sixth transects.
(b) - The pattern is consistent with greater cassowary use of interior habitat. - Signs are an indirect measure, and variation in persistence or visibility can affect recorded counts. - Six transects from one reserve do not establish a general population response. - The evidence supports an association within the sampled reserve but does not prove that forest edges cause avoidance.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Signs increase from 1 near the edge to 8 on the two deepest transects.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The increase levels off between the fifth and sixth transects.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: The pattern is consistent with greater cassowary use of interior habitat.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Signs are an indirect measure, and variation in persistence or visibility can affect recorded counts.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Six transects from one reserve do not establish a general population response.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: The evidence supports an association within the sampled reserve but does not prove that forest edges cause avoidance.
Question 3
(a) - The pattern is autosomal dominant under the stated models and assumptions. - Affected parents I-1 and I-2 have unaffected daughter II-3; two affected parents would produce only affected children under either recessive model. - Affected father I-1 has unaffected daughter II-3; an X-linked dominant father would pass the dominant allele to every daughter, excluding that model.
(b) - II-2 is aa; II-1 is Aa because unaffected child III-2 is aa and must receive a from each parent. - For Aa × aa, each child has probability 1/2 of being aa and unaffected, and 1/2 of being Aa and affected. - Independent births give a probability of (1/2) × (1/2) = 1/4 for both of the next two children being unaffected; the previous children's outcomes do not change this probability.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The pattern is autosomal dominant under the stated models and assumptions.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Affected parents I-1 and I-2 have unaffected daughter II-3; two affected parents would produce only affected children under either recessive model.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Affected father I-1 has unaffected daughter II-3; an X-linked dominant father would pass the dominant allele to every daughter, excluding that model.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: II-2 is aa; II-1 is Aa because unaffected child III-2 is aa and must receive a from each parent.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: For Aa × aa, each child has probability 1/2 of being aa and unaffected, and 1/2 of being Aa and affected.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Independent births give a probability of (1/2) × (1/2) = 1/4 for both of the next two children being unaffected; the previous children's outcomes do not change this probability.
Question 4
(a) - Detritivores ingest organic carbon and transfer some into their biomass. - Detritivore and microbial respiration return carbon dioxide to the atmosphere. - Unassimilated and dead material remains available to decomposers or soil carbon pools.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Detritivores ingest organic carbon and transfer some into their biomass.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Detritivore and microbial respiration return carbon dioxide to the atmosphere.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Unassimilated and dead material remains available to decomposers or soil carbon pools.
Question 5
(a) - The canyon geographically isolates the populations and reduces movement of alleles between them. - Mutation, genetic drift and different selection pressures can then change allele frequencies independently. - Continued reduction in gene flow permits genetic differences to accumulate across generations.
(b) - Different calls can reduce mating between eastern and western frogs. - Lower viability of between-population offspring provides evidence of reproductive isolation. - Greater between-population sequence differences support genetic divergence rather than a call difference alone.
(c) - Experimental crosses may not represent mate choice or offspring survival in the wild. - The number and geographic coverage of genetic samples are not stated, so the sequence comparison may not represent population-wide genetic variation. - Current movement across the canyon and persistence of the differences over time are not established.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The canyon geographically isolates the populations and reduces movement of alleles between them.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Mutation, genetic drift and different selection pressures can then change allele frequencies independently.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Continued reduction in gene flow permits genetic differences to accumulate across generations.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Different calls can reduce mating between eastern and western frogs.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Lower viability of between-population offspring provides evidence of reproductive isolation.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Greater between-population sequence differences support genetic divergence rather than a call difference alone.
Part c (1 mark)
Awards one mark for accurately establishing this question-specific point: Experimental crosses may not represent mate choice or offspring survival in the wild.
Part c (1 mark)
Awards one mark for accurately establishing this question-specific point: The number and geographic coverage of genetic samples are not stated, so the sequence comparison may not represent population-wide genetic variation.
Part c (1 mark)
Awards one mark for accurately establishing this question-specific point: Current movement across the canyon and persistence of the differences over time are not established.
Question 6
(a) - The approximately 1:1 phenotype ratio is expected from Pp × pp. - The purple parent is therefore heterozygous Pp.
(b) - Random segregation causes sampling variation around the expected ratio. - A larger offspring count reduces proportional sampling error but does not make the genetic model immune to other explanations.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The approximately 1:1 phenotype ratio is expected from Pp × pp.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The purple parent is therefore heterozygous Pp.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Random segregation causes sampling variation around the expected ratio.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: A larger offspring count reduces proportional sampling error but does not make the genetic model immune to other explanations.
Question 7
(a) - The heatwave is a selection pressure because survival differs between the stated genotypes. - Higher survival of H carriers and the rise from 0.27 to 0.48 support positive selection for H in this event. - One event does not establish that H will remain advantageous under other conditions or continue increasing.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The heatwave is a selection pressure because survival differs between the stated genotypes.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Higher survival of H carriers and the rise from 0.27 to 0.48 support positive selection for H in this event.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: One event does not establish that H will remain advantageous under other conditions or continue increasing.
Question 8
(a) - An occupied wetland may yield no call during one survey, creating false absences. - Repeated visits allow occupancy to be estimated separately from imperfect detection.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: An occupied wetland may yield no call during one survey, creating false absences.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Repeated visits allow occupancy to be estimated separately from imperfect detection.
Question 9
(a) - The interaction is mutualism because both species gain a resource-related benefit. - The fungus gains organic carbon while the tree gains improved mineral acquisition.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The interaction is mutualism because both species gain a resource-related benefit.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The fungus gains organic carbon while the tree gains improved mineral acquisition.
Question 10
(a) - Biomass declined at 20% light, changed little at 50% light and increased most at 90% light. - Within the tested range, greater light availability is associated with greater net biomass gain. - The result is consistent with light limiting photosynthetic production in the low-light treatment.
(b) - Equal starting biomass and controlled abiotic conditions make light the main stated treatment difference. - Independent aquaria provide replicate experimental units rather than treating shoots within one aquarium as independent. - Random assignment and rotation reduce systematic allocation and bench-position effects.
(c) - Photosynthetic oxygen production measures a process response to the light treatment. - Respiration data distinguish gross production from net production. - Leaf area and final dry biomass quantify biological outcomes using consistent endpoints. - The six-week aquarium result still does not establish responses across all field turbidity and duration ranges.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Biomass declined at 20% light, changed little at 50% light and increased most at 90% light.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: Within the tested range, greater light availability is associated with greater net biomass gain.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The result is consistent with light limiting photosynthetic production in the low-light treatment.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Equal starting biomass and controlled abiotic conditions make light the main stated treatment difference.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Independent aquaria provide replicate experimental units rather than treating shoots within one aquarium as independent.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: Random assignment and rotation reduce systematic allocation and bench-position effects.
Part c (1 mark)
Awards one mark for accurately establishing this question-specific point: Photosynthetic oxygen production measures a process response to the light treatment.
Part c (1 mark)
Awards one mark for accurately establishing this question-specific point: Respiration data distinguish gross production from net production.
Part c (1 mark)
Awards one mark for accurately establishing this question-specific point: Leaf area and final dry biomass quantify biological outcomes using consistent endpoints.
Part c (1 mark)
Awards one mark for accurately establishing this question-specific point: The six-week aquarium result still does not establish responses across all field turbidity and duration ranges.
Question 11
(a) - The sample is heterozygous Ll because it contains the uncut L fragment and both l restriction fragments. - The fragment sizes are consistent because 260 bp + 160 bp = 420 bp.
(b) - The ladder and known genotypes support fragment-size identification and show the amplification and digestion pattern worked as expected. - The clear no-template lane reduces a contamination explanation but does not by itself prove complete digestion in every sample.
Detailed marking criteria
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The sample is heterozygous Ll because it contains the uncut L fragment and both l restriction fragments.
Part a (1 mark)
Awards one mark for accurately establishing this question-specific point: The fragment sizes are consistent because 260 bp + 160 bp = 420 bp.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: The ladder and known genotypes support fragment-size identification and show the amplification and digestion pattern worked as expected.
Part b (1 mark)
Awards one mark for accurately establishing this question-specific point: The clear no-template lane reduces a contamination explanation but does not by itself prove complete digestion in every sample.
Diagnostic Checklist
| Topic | Questions | Marks | Marks Lost | Action |
|---|---|---|---|---|
| Unit 3 Topic 1 - Biodiversity and populations | Q1, Q2, Q8 | 11 | ___ | Review classification, sampling, population estimates, diversity indices and evidence limits. |
| Unit 3 Topic 2 - Functioning ecosystems and succession | Q4, Q9, Q10 | 15 | ___ | Review energy transfer, biogeochemical cycling, species interactions, disturbance and succession. |
| Unit 4 Topic 1 - Genetics and heredity | Q3, Q6, Q11 | 14 | ___ | Review DNA, gene expression, meiosis, inheritance, biotechnology and quantitative genetic reasoning. |
| Unit 4 Topic 2 - Continuity of life on Earth | Q5, Q7 | 12 | ___ | Review mutation, natural selection, speciation, phylogeny and converging evolutionary evidence. |