A Level H2 Biology Evolution Diversity Quiz

A-Level Biology H2 Quiz - Evolution Diversity

Name: ___________________________
Class: ___________________________
Date: ___________________________
Score: ___________ / 60

Duration: 75 minutes
Total Marks: 60

Instructions:

1. Answer all 20 questions.
2. Section A (Q1–7): Short structured recall and definition (2 marks each).
3. Section B (Q8–14): Data interpretation and application (3–5 marks each).
4. Section C (Q15–20): Extended response and synthesis (6–8 marks each).
5. Show all working for calculation questions. Use pen and write clearly.

---

Section A: Short Structured Questions (14 marks)

1. Define the term biological evolution and state one mechanism by which it occurs. [2]

---

2. State the difference between allopatric and sympatric speciation. [2]

---

3. Using the Hardy–Weinberg principle, state the meaning of the term $q^2$ in the equation $p^2 + 2pq + q^2 = 1$. [2]

---

4. Give one example of a prezygotic isolating mechanism and one example of a postzygotic isolating mechanism. [2]

---

5. Explain what is meant by genetic drift and name one situation where it is most pronounced. [2]

---

6. State the three domains of life according to the modern classification system and give one distinguishing feature of each. [2]

---

7. Define biodiversity and state one human activity that reduces it. [2]

---

---

Section B: Data Interpretation and Application (26 marks)

8. A population of 2000 snails was found to have 320 individuals homozygous recessive for a banding pattern allele ($aa$). Assuming the population is in Hardy–Weinberg equilibrium, calculate: (a) the frequency of the recessive allele $q$; [2] (b) the frequency of the dominant allele $p$; [1] (c) the number of heterozygous individuals ($2pq$) in the population. [2]

---

9. The table below shows the number of bird species observed on four islands of different sizes.

Island	Area (km²)	Number of bird species
A	10	12
B	50	21
C	120	34
D	300	48

With reference to the data, describe the relationship between island area and species richness and suggest one ecological reason for this trend. [3]

---

10.

Generated graph for Q10.

With reference to Fig. Q10-fig1, explain how the drought acted as a selective pressure on beak depth. [4]

---

11. A species of insect shows two colour forms, green and brown. A predator preferentially eats the more visible form against the background. Over 10 generations the frequency of the green form dropped from 0.7 to 0.2. (a) Identify the type of selection occurring. [1] (b) Explain how this changes allele frequencies in the population. [3]

---

12. Compare convergent and divergent evolution, giving one named example of each. [4]

---

13. The DNA sequences of a gene from three species are shown:

Species X: ATG CAA GTT Species Y: ATG CTA GTT Species Z: ATG CAA GTC

Using this evidence, state which two species are most closely related and explain your reasoning. [3]

---

14. A farmer uses a pesticide that kills 95% of pests in generation 1. After 5 years the same dose kills only 20%. Explain the evolutionary basis for this observation. [4]

---

---

Section C: Extended Response and Synthesis (20 marks)

15. Describe the process of allopatric speciation by geographic isolation, using a named organism example. Include in your answer: isolation, genetic divergence, reproductive isolation, and formation of new species. [8]

---

16. The Hardy–Weinberg equation is used to test whether a population is evolving. Explain the assumptions of the model and calculate the expected genotype frequencies for a population where $p = 0.6$. Show all steps. [6]

---

17.

Generated diagram for Q17.

With reference to Fig. Q17-fig1, explain how a cladogram is used to represent evolutionary relationships and identify the two most recently diverged taxa. [6]

---

18. Evaluate the evidence from molecular biology (including DNA and protein sequences) for the theory of common descent. [7]

---

19. Discuss the role of mutation and recombination as sources of variation for natural selection to act upon. [6]

---

20. A lake was divided by a landslide into two separate ponds. After 500 years the fish in the two ponds showed differences in fin shape and mating calls. Explain how speciation may have occurred and state one test a biologist could do to confirm speciation. [7]

---

</stage3_quiz_answers_md>

A-Level Biology H2 Quiz - Evolution Diversity (Answer Key)

Total Marks: 60
Section A: 14 marks
Section B: 26 marks
Section C: 20 marks

---

Section A: Short Structured Questions

1. [2 marks]

• Definition: Biological evolution is the change in allele frequencies in a population over generations. [1]
• Mechanism: e.g., natural selection / mutation / genetic drift / gene flow. [1] Teaching note: Evolution acts on populations, not individuals. A mechanism must alter allele frequency, not just appearance.

2. [2 marks]

• Allopatric: speciation due to geographic separation (physical barrier). [1]
• Sympatric: speciation within same habitat without geographic barrier (e.g., polyploidy, niche splitting). [1]

3. [2 marks]

• $q^2$ represents the frequency of homozygous recessive individuals in the population. [2] Marking: State "homozygous recessive" or "aa individuals" for full marks.

4. [2 marks]

• Prezygotic: e.g., habitat isolation, temporal isolation, behavioural isolation, mechanical isolation. [1]
• Postzygotic: e.g., hybrid sterility (mule), reduced hybrid viability. [1]

5. [2 marks]

• Genetic drift: random change in allele frequencies due to chance events. [1]
• Most pronounced in small populations / after bottleneck / founder effect. [1]

6. [2 marks]

• Bacteria (no nucleus / prokaryotes); Archaea (prokaryotes, distinct membranes); Eukarya (membrane-bound nucleus). [2, 1 each feature]

7. [2 marks]

• Biodiversity: variety of life at gene, species, ecosystem level. [1]
• Activity: deforestation / pollution / overfishing. [1]

---

Section B: Data Interpretation

8. [5 marks total] Given: $N = 2000$, $aa = 320$. (a) $q^2 = 320/2000 = 0.16$; $q = \sqrt{0.16} = 0.4$. [2] (b) $p = 1 - q = 1 - 0.4 = 0.6$. [1] (c) $2pq = 2 \times 0.6 \times 0.4 = 0.48$; number = $0.48 \times 2000 = 960$. [2] Common mistake: using $q$ not $q^2$ directly.

9. [3 marks]

• Relationship: larger area supports more species (positive correlation). [1]
• Reason: larger area = more habitats / resources / lower extinction. [2]

10. [4 marks]

• Drought reduced small soft seeds; only deep large seeds remained. [1]
• Birds with deeper beaks accessed food, survived. [1]
• Shallow-beaked died → directional selection. [1]
• Mean beak depth shifted from 9.2 to 10.4 mm in survivors. [1]

11. [4 marks] (a) Directional selection (or predation-mediated). [1] (b) Predation removed green phenotype; allele for green reduced; brown allele increased. [3]

12. [4 marks]

• Convergent: unrelated species evolve similar traits (e.g., dolphin & shark streamline). [2]
• Divergent: related species become different (e.g., Darwin's finches). [2]

13. [3 marks]

• X and Z most closely related (differ by 1 bp at third codon). [1]
• Y differs by 1 bp at second codon from X; Z differs at third. [2]

14. [4 marks]

• Initial population had resistant alleles at low frequency. [1]
• Pesticide killed susceptible; survivors bred. [1]
• Resistance allele frequency rose. [1]
• After years, most were resistant. [1]

---

Section C: Extended Response

15. [8 marks]

• Isolation: river splits population. [2]
• Divergence: different selection, mutation, drift. [2]
• Reproductive isolation: no gene flow, incompatible mating. [2]
• New species: cannot interbreed if reunited (e.g., Grand Canyon squirrels). [2]

16. [6 marks] Assumptions: no mutation, no migration, random mating, large population, no selection. [3] $p=0.6, q=0.4$; $p^2=0.36$, $2pq=0.48$, $q^2=0.16$. [3]

17. [6 marks]

• Cladogram shows shared derived traits; branch order = divergence. [3]
• Most recent: two taxa sharing latest node (e.g., D & E if labelled). [3] Image must show trait markers at nodes.

18. [7 marks]

• DNA similarity reflects common ancestry. [2]
• Cytochrome c / rRNA conserved. [2]
• Universal genetic code. [2]
• Cladistics from molecules matches fossils. [1]

19. [6 marks]

• Mutation creates new alleles. [2]
• Recombination shuffles in meiosis. [2]
• Selection acts on variation. [2]

20. [7 marks]

• Isolation → divergence → reproductive isolation. [4]
• Test: cross fish; if no offspring / sterile → speciation. [3] </stage3_quiz_answers_md>

<stage3_quiz_md>

A-Level Biology H2 Quiz - Evolution Diversity

Name: ___________________________
Class: ___________________________
Date: ___________________________
Score: ___________ / 60

Duration: 75 minutes
Total Marks: 60

Instructions:

1. Answer all 20 questions.
2. Section A (Q1–7): Short structured recall and definition (2 marks each).
3. Section B (Q8–14): Data interpretation and application (3–5 marks each).
4. Section C (Q15–20): Extended response and synthesis (6–8 marks each).
5. Show all working for calculation questions. Use pen and write clearly.

---

Section A: Short Structured Questions (14 marks)

1. Define the term biological evolution and state one mechanism by which it occurs. [2]

---

2. State the difference between allopatric and sympatric speciation. [2]

---

3. Using the Hardy–Weinberg principle, state the meaning of the term $q^2$ in the equation $p^2 + 2pq + q^2 = 1$. [2]

---

4. Give one example of a prezygotic isolating mechanism and one example of a postzygotic isolating mechanism. [2]

---

5. Explain what is meant by genetic drift and name one situation where it is most pronounced. [2]

---

6. State the three domains of life according to the modern classification system and give one distinguishing feature of each. [2]

---

7. Define biodiversity and state one human activity that reduces it. [2]

---

---

Section B: Data Interpretation and Application (26 marks)

8. A population of 2000 snails was found to have 320 individuals homozygous recessive for a banding pattern allele ($aa$). Assuming the population is in Hardy–Weinberg equilibrium, calculate: (a) the frequency of the recessive allele $q$; [2] (b) the frequency of the dominant allele $p$; [1] (c) the number of heterozygous individuals ($2pq$) in the population. [2]

---

9. The table below shows the number of bird species observed on four islands of different sizes.

Island	Area (km²)	Number of bird species
A	10	12
B	50	21
C	120	34
D	300	48

With reference to the data, describe the relationship between island area and species richness and suggest one ecological reason for this trend. [3]

---

10.

Generated graph for Q10.

With reference to Fig. Q10-fig1, explain how the drought acted as a selective pressure on beak depth. [4]

---

11. A species of insect shows two colour forms, green and brown. A predator preferentially eats the more visible form against the background. Over 10 generations the frequency of the green form dropped from 0.7 to 0.2. (a) Identify the type of selection occurring. [1] (b) Explain how this changes allele frequencies in the population. [3]

---

12. Compare convergent and divergent evolution, giving one named example of each. [4]

---

13. The DNA sequences of a gene from three species are shown:

Species X: ATG CAA GTT Species Y: ATG CTA GTT Species Z: ATG CAA GTC

Using this evidence, state which two species are most closely related and explain your reasoning. [3]

---

14. A farmer uses a pesticide that kills 95% of pests in generation 1. After 5 years the same dose kills only 20%. Explain the evolutionary basis for this observation. [4]

---

---

Section C: Extended Response and Synthesis (20 marks)

15. Describe the process of allopatric speciation by geographic isolation, using a named organism example. Include in your answer: isolation, genetic divergence, reproductive isolation, and formation of new species. [8]

---

16. The Hardy–Weinberg equation is used to test whether a population is evolving. Explain the assumptions of the model and calculate the expected genotype frequencies for a population where $p = 0.6$. Show all steps. [6]

---

17.

Generated diagram for Q17.

With reference to Fig. Q17-fig1, explain how a cladogram is used to represent evolutionary relationships and identify the two most recently diverged taxa. [6]

---

18. Evaluate the evidence from molecular biology (including DNA and protein sequences) for the theory of common descent. [7]

---

19. Discuss the role of mutation and recombination as sources of variation for natural selection to act upon. [6]

---

20. A lake was divided by a landslide into two separate ponds. After 500 years the fish in the two ponds showed differences in fin shape and mating calls. Explain how speciation may have occurred and state one test a biologist could do to confirm speciation. [7]

---