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Secondary 4 Pure Biology Evolution Diversity Quiz
Free Sec 4 Pure Biology Evolution Diversity quiz, Qwen3.6 Exam version, with questions, answers, and O Level-style practice for Singapore students.
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Secondary 4 Pure Biology Quiz - Evolution Diversity (Answer Key)
Total Marks: 40
Section A: Multiple Choice Questions
1. B
[1]
Reasoning: Natural selection acts on existing variation; individuals with advantageous traits survive/reproduce more. A is Lamarckian; C is incorrect as rates vary; D is incorrect as mutations are random, not caused by need.
2. C
[1]
Reasoning: Same basic structure (bone arrangement) but different functions indicates common ancestry (homologous).
3. A
[1]
Reasoning: Mutation (variation) exists first -> Selection pressure (antibiotic) applied -> Survivors reproduce -> Population shifts.
4. B
[1]
Reasoning: Higher similarity in amino acid sequences implies fewer mutations have accumulated since divergence, indicating a more recent common ancestor.
5. D
[1]
Reasoning: Evolution is not conscious. A, B, and C are the three necessary conditions for natural selection.
Section B: Structured Questions
6. (a)
- Light-colored moths blended in with the lichen-covered trees (camouflage).
- Predators (birds) could not see them easily, so they survived and reproduced more than dark moths.
[2]
(b)
- The trees became dark due to soot, making light moths visible to predators.
- Dark moths were now camouflaged and had a survival advantage.
- Dark moths survived predation, reproduced, and passed the dark allele to offspring.
- Over time, the frequency of the dark allele increased in the population.
[3] (1 mark for survival advantage/camouflage, 1 mark for reproduction/passing alleles, 1 mark for change in allele frequency)
7. (a)
- Differences in characteristics/features between individuals of the same species.
[1]
(b)
- Mutation / Genetic recombination (meiosis/crossing over) / Sexual reproduction.
[2] (Any two)
(c)
- Finches with larger beaks could crack hard seeds and survive; those with small beaks starved.
- Large-beaked finches reproduced, passing the trait to offspring.
- Over many generations, the population shifted to have larger beaks.
- If isolated, this could lead to reproductive isolation and speciation.
[3]
8. (a)
- Reduction in the number of toes (from multiple to one).
- OR Increase in limb length/size.
[1]
(b)
- Change from forest to grassland/prairie.
- Need for faster running to escape predators in open terrain.
[1]
9. (a)
- Homologous: Common ancestor; Same or different functions.
- Analogous: Different ancestors; Same functions.
[3] (1 mark per correct blank, max 3)
(b)
- They arise due to similar environmental pressures (convergent evolution), not shared ancestry.
[1]
10. (a)
- As the drought progressed, the average beak depth increased.
[1]
(b)
- The genetic variation for large beaks became fixed or more common in the gene pool.
- Even if small seeds returned, the population had already evolved; or large seeds remained the dominant food source.
- Evolution is not reversible in the short term without specific selection pressure against large beaks.
[2]
11. (a)
- Artificial selection: Humans choose the traits; Natural selection: Environment chooses the traits.
- Artificial selection is much faster.
[2]
(b)
- Reduces genetic diversity/variations.
- Makes the population vulnerable to diseases or environmental changes.
[1]
12. (a)
- Fossilization is rare (requires specific conditions).
- Soft tissues rarely fossilize.
- Incomplete record (gaps in transitional forms).
[2] (Any two)
(b)
- They show direct evidence of past life forms and transitional features linking groups.
- They allow dating of evolutionary events.
[1]
13. (a)
- Sigmoid (S-shaped) curve / Logistic growth.
[1]
(b)
- Limited food/resources.
- Accumulation of waste/toxins.
- Disease/Competition.
[2] (Any two)
14. (a)
- Mutations accumulate over time.
- Closely related species diverged recently, so fewer mutations have accumulated, resulting in more similar sequences.
[2]
(b)
- It is a fundamental protein found in almost all aerobic organisms.
- It evolves slowly, allowing comparison across distant species.
[1]
15. (a)
- A and B.
[1]
(b)
- The node where the lineage leading to C diverges from the lineage leading to A and B.
[1]
Section C: Free Response Questions
16. Allopatric Speciation
- A physical barrier (e.g., mountain, river) separates a population into two groups.
- The two groups experience different environmental conditions/selection pressures.
- Mutations occur randomly in each group.
- Natural selection favors different traits in each group.
- Over time, genetic differences accumulate.
- Eventually, the groups become reproductively isolated (cannot interbreed) even if the barrier is removed.
[4] (1 mark per distinct point, max 4)
17. "Evolution is not goal-oriented"
- Mutations are random; they do not occur because an organism "needs" them.
- Natural selection acts on existing variation; it does not create traits.
- Environmental changes are unpredictable; what is advantageous now may not be later.
- Evolution has no end goal or perfect state; it is simply adaptation to current conditions.
[3]
18. Genetic Drift
- Random changes in allele frequencies due to chance events (not selection).
- Significant in small populations (e.g., bottleneck effect, founder effect).
- Can lead to loss of alleles or fixation of harmful alleles purely by chance.
[2]
19. (a) Pesticide Resistance
- Variation exists in the insect population; some have a mutation for resistance.
- Pesticide kills non-resistant insects.
- Resistant insects survive and reproduce.
- Offspring inherit the resistance gene.
- Over generations, the population becomes predominantly resistant.
[3]
(b) Strategy
- Rotate pesticides with different modes of action.
- Use biological control agents.
- Leave untreated refuges for non-resistant insects to maintain susceptible genes.
[1]
20. Comparative Anatomy vs. Biochemistry
- Anatomy: Looks at structural similarities (homologous structures). Good for visible traits but can be misleading due to convergent evolution (analogous structures).
- Biochemistry: Compares DNA/protein sequences. More precise and quantitative. Can compare very different organisms (e.g., bacteria and humans).
- Conclusion: Both support common ancestry, but biochemistry provides a molecular clock and resolves relationships where anatomy is ambiguous.
[4] (2 marks for describing each, 1 mark for comparison/limitation, 1 mark for synthesis)