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Secondary 4 Pure Biology Evolution Diversity Quiz

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Questions

Secondary 4 Pure Biology Quiz - Evolution Diversity

Name: _________________________ Class: _________________________ Date: _________________________ Score: _____ / 50

Duration: 45 minutes Total Marks: 50

Instructions:

Answer ALL questions in the spaces provided.
Write your answers clearly and legibly.
Marks are indicated in brackets [ ].
Where calculations are required, show all working clearly.
Diagrams may be used to support your answers where appropriate.

Section A: Multiple Choice Questions [5 marks]

Circle the correct answer for each question.

1. Which of the following provides the strongest evidence that two organisms share a recent common ancestor?

A. They live in the same habitat. B. They have similar DNA sequences. C. They occupy the same trophic level. D. They have the same number of chromosomes.

[1 mark]

2. The wings of a bat and the wings of a butterfly are considered:

A. Homologous structures B. Analogous structures C. Vestigial structures D. Identical structures

[1 mark]

3. Natural selection acts directly on an organism's:

A. Genotype B. Phenotype C. Allele frequency D. DNA sequence

[1 mark]

4. Which of the following is an example of a vestigial structure in humans?

A. Thumb B. Appendix C. Heart D. Lung

[1 mark]

5. The development of antibiotic resistance in bacteria is an example of:

A. Artificial selection B. Natural selection C. Genetic drift D. Gene flow

[1 mark]

Section B: Short Answer Questions [20 marks]

Answer all questions in the spaces provided.

6. Define the term "species" as used in biological classification.

[2 marks]

7. The diagram below shows the forelimbs of four different vertebrates: a human, a whale, a bat, and a bird.

(a) Name the type of structures represented by these forelimbs.

[1 mark]

(b) Explain how these structures provide evidence for evolution.

[3 marks]

8. State two differences between natural selection and artificial selection.

[4 marks]

Difference 1:

Difference 2:

9. Explain how the fossil record provides evidence for evolution. In your answer, refer to at least one specific example.

[4 marks]

10. A population of insects contains both green and brown individuals. The insects live on the bark of trees. Over several generations, the proportion of brown insects increases significantly.

(a) Suggest a reason for this change in the population.

[2 marks]

(b) Name the scientist who proposed the theory of evolution by natural selection.

[1 mark]

Section C: Structured Response Questions [25 marks]

Answer all questions in the spaces provided.

11. The table below shows the percentage difference in the DNA sequence of a particular gene between humans and four other primate species.

Primate Species	Percentage Difference in DNA (%)
Chimpanzee	1.2
Gorilla	1.6
Orangutan	3.1
Gibbon	4.8

(a) Using the data in the table, state which primate is most closely related to humans. Explain your answer.

[2 marks]

(b) Explain how comparing DNA sequences can be used to determine evolutionary relationships between species.

[3 marks]

[1 mark]

12. The peppered moth (Biston betularia) exists in two forms: a light-coloured form and a dark (melanic) form. Before the Industrial Revolution in England, the light form was more common. During the Industrial Revolution, when tree trunks became darkened by soot, the dark form became more common.

(a) Explain how natural selection led to the change in the frequency of the dark form of the peppered moth during the Industrial Revolution.

[4 marks]

(b) After clean air legislation was introduced in the 1950s, the frequency of the light form increased again. Explain why.

[2 marks]

13. The diagram below shows a phylogenetic tree representing the evolutionary relationships between five species (A, B, C, D, and E).

        ┌───── Species A
    ┌───┤
    │   └───── Species B
────┤
    │       ┌───── Species C
    │   ┌───┤
    └───┤   └───── Species D
        │
        └───────── Species E

(a) State which two species are most closely related. Explain your answer with reference to the diagram.

[2 marks]

(b) State which species is the most distantly related to the other four species. Explain your answer.

[2 marks]

(c) Explain how molecular evidence, such as comparing the amino acid sequences of cytochrome c, can be used to construct phylogenetic trees.

[3 marks]

14. Antibiotic resistance in bacteria is a growing concern worldwide. Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of bacteria that is resistant to several antibiotics.

(a) Explain how a population of bacteria can develop resistance to an antibiotic through natural selection.

[4 marks]

(b) Suggest two practices that can help reduce the spread of antibiotic resistance.

[2 marks]

Practice 1:

Practice 2:

15. Explain the difference between convergent evolution and divergent evolution. Provide one example of each.

[4 marks]

Section D: Data Analysis and Application Questions [0 marks - content moved]

Note: Questions 16-20 are integrated into this section.

16. The Galapagos finches studied by Charles Darwin show a variety of beak shapes adapted to different food sources.

(a) Explain how adaptive radiation led to the diversity of beak shapes in Galapagos finches.

[3 marks]

(b) State one type of evidence, besides fossils, that scientists could use to support the hypothesis that these finches share a common ancestor.

[1 mark]

17. A scientist compares the amino acid sequence of haemoglobin from five different species. The number of amino acid differences compared to human haemoglobin is shown below.

Species	Number of Amino Acid Differences
Gorilla	1
Dog	15
Frog	62
Lamprey	125

(a) Based on the data, which species is most closely related to humans? Explain your answer.

[2 marks]

(b) Explain why species that are more distantly related have more amino acid differences in their haemoglobin.

[2 marks]

18. In a population of rabbits, fur colour is controlled by a single gene with two alleles: B (brown, dominant) and b (white, recessive). In a population of 100 rabbits, 84 have brown fur and 16 have white fur.

(a) Calculate the frequency of the recessive allele (b) in this population. Show your working.

[2 marks]

(b) State two conditions that must be met for this population to be in Hardy-Weinberg equilibrium.

[2 marks]

19. The graph below shows the change in the frequency of a pesticide resistance allele in a mosquito population over 10 years. The pesticide was first introduced in Year 2.

Frequency of
Resistance Allele (%)
100 |
 80 |                    *
    |                 *  *
 60 |              *  *  *
    |           *  *  *  *
 40 |        *  *  *  *  *
    |     *  *  *  *  *  *
 20 |  *  *  *  *  *  *  *
    |  *  *  *  *  *  *  *
  0 |__*__*__*__*__*__*__*__*__*__*__ Year
     1  2  3  4  5  6  7  8  9  10

(a) Describe the trend shown in the graph from Year 1 to Year 10.

[2 marks]

(b) Explain the trend described in (a) in terms of natural selection.

[3 marks]

20. "The theory of evolution is just a theory, not a fact." Discuss this statement, explaining the scientific meaning of the word "theory" and providing evidence that supports the theory of evolution.

[4 marks]

END OF QUIZ

Check your answers carefully before submitting.

Answers

Secondary 4 Pure Biology Quiz - Evolution Diversity — ANSWER KEY

Total Marks: 50

Section A: Multiple Choice Questions [5 marks]

1. B. They have similar DNA sequences. [1 mark]

Marking note: Accept B only. Similar DNA sequences indicate recent common ancestry. Habitat, trophic level, and chromosome number are less reliable indicators.

2. B. Analogous structures [1 mark]

Marking note: Bat wings (mammalian forelimb) and butterfly wings (insect wing) have different evolutionary origins but similar functions, making them analogous structures.

3. B. Phenotype [1 mark]

Marking note: Natural selection acts on the expressed traits (phenotype) of an organism, not directly on the genotype.

4. B. Appendix [1 mark]

Marking note: The appendix is a vestigial structure with reduced or no function in humans, inherited from ancestors where it had a digestive function.

5. B. Natural selection [1 mark]

Marking note: Antibiotic resistance develops when bacteria with resistance genes survive and reproduce, passing on the resistance trait — a classic example of natural selection.

Section B: Short Answer Questions [20 marks]

6. A species is a group of organisms that can interbreed to produce fertile offspring under natural conditions. [2 marks]

Marking notes:
- Award 1 mark for "group of organisms that can interbreed"
- Award 1 mark for "produce fertile offspring" or "reproductively isolated from other groups"
- Accept reference to "biological species concept"
- Do not accept definitions based solely on physical appearance

7. (a) Homologous structures [1 mark]

Marking note: Accept "homologous organs" or "homologous features."

(b) Homologous structures provide evidence for evolution because: [3 marks]

They have the same basic structural plan / same arrangement of bones (pentadactyl limb) [1 mark]
This suggests they evolved from a common ancestor that possessed this basic structure [1 mark]
The structures have been modified / adapted over time for different functions in different environments (e.g., grasping in humans, swimming in whales, flying in bats and birds) [1 mark]
Marking note: Award marks for clear explanation linking common ancestry to structural similarity and functional divergence.

8. Two differences between natural selection and artificial selection: [4 marks]

Difference 1:

In natural selection, the environment / nature selects which individuals survive and reproduce [1 mark]
In artificial selection, humans select which individuals breed based on desired traits [1 mark]

Difference 2:

Natural selection results in adaptations that increase survival and reproductive success in the natural environment [1 mark]
Artificial selection results in traits that are desirable to humans but may not increase survival in the wild [1 mark]

Marking notes:

Accept other valid differences, e.g., natural selection is slower, artificial selection is faster; natural selection increases fitness, artificial selection may decrease fitness.
Award 1 mark for each clearly stated difference with contrast between the two processes.

9. The fossil record provides evidence for evolution because: [4 marks]

Fossils show that organisms that lived in the past were different from organisms alive today, indicating that life has changed over time [1 mark]
Fossils can be arranged in chronological order (using relative dating of rock layers or radiometric dating), showing a sequence of change [1 mark]
Transitional fossils show intermediate forms between ancestral and modern species, demonstrating gradual change [1 mark]
Specific example: The fossil record of the horse shows a gradual increase in size, reduction in the number of toes, and changes in tooth structure over millions of years / Archaeopteryx shows features of both reptiles (teeth, long bony tail) and birds (feathers, wings), indicating a transitional form between reptiles and birds [1 mark]

Marking notes:

Award up to 3 marks for general explanation of how fossils provide evidence
Award 1 mark for a named specific example with brief description
Accept other valid examples (e.g., whale evolution, human evolution)

10. (a) The increase in brown insects suggests that brown individuals are better camouflaged against the tree bark, making them less visible to predators. [1 mark] As a result, more brown insects survive to reproduce, passing on the brown colouration allele to their offspring. Over generations, the frequency of the brown allele increases in the population. [1 mark]

Marking note: Award marks for linking camouflage/survival advantage to increased reproduction and change in allele frequency.

(b) Charles Darwin [1 mark]

Marking note: Accept "Darwin" only. Do not accept "Lamarck" or "Wallace" alone (though Wallace independently proposed the theory, Darwin is the primary scientist credited).

Genetic drift
Gene flow / migration
Mutation
Non-random mating
Marking note: Accept any valid factor that changes allele frequencies. Do not accept "natural selection" as this is already referenced in the question.

Section C: Structured Response Questions [25 marks]

11. (a) Chimpanzee is most closely related to humans. [1 mark] This is because chimpanzees have the lowest percentage difference in DNA (1.2%), indicating the most recent common ancestor / closest evolutionary relationship. [1 mark]

Marking note: Must state chimpanzee AND explain using data from the table.

(b) Comparing DNA sequences can determine evolutionary relationships because: [3 marks]

DNA sequences are passed from generation to generation, and mutations accumulate over time [1 mark]
Species that share a more recent common ancestor will have more similar DNA sequences (fewer accumulated differences) [1 mark]
By comparing the degree of similarity/difference in DNA sequences, scientists can estimate how long ago two species diverged from a common ancestor and construct evolutionary trees [1 mark]

Marking note: Award marks for clear explanation linking DNA similarity to recency of common ancestry and divergence time.

Different genes may evolve at different rates, so comparing only one gene may not give a complete picture
Horizontal gene transfer (especially in bacteria) can complicate DNA comparisons
DNA sequences can only be compared for living species, not extinct species (unless DNA is preserved)
Convergent evolution can produce similar DNA sequences in distantly related species
Marking note: Accept any valid limitation.

12. (a) Natural selection led to the change in frequency of the dark form as follows: [4 marks]

Before the Industrial Revolution, tree trunks were light-coloured, so the light form was camouflaged and the dark form was more visible to predators (birds) [1 mark]
During the Industrial Revolution, soot darkened tree trunks, so the dark form became better camouflaged while the light form became more visible [1 mark]
Dark moths had a selective advantage — they were less likely to be eaten by predators, so more dark moths survived to reproduce [1 mark]
The dark moths passed on the allele for dark colouration to their offspring, and over many generations, the frequency of the dark allele increased in the population [1 mark]

Marking note: Award marks for clear step-by-step explanation linking environmental change → differential survival → differential reproduction → change in allele frequency.

(b) After clean air legislation, the frequency of the light form increased again because: [2 marks]

Air pollution decreased, so tree trunks became lighter again as soot was washed away [1 mark]
The light form became better camouflaged once more, giving it a selective advantage, so more light moths survived and reproduced, increasing the frequency of the light allele [1 mark]

Marking note: Award marks for linking environmental change to change in selective pressure and change in allele frequency.

13. (a) Species C and Species D are most closely related. [1 mark] They share the most recent common ancestor (the node where their branches meet is the most recent split on the tree). [1 mark]

Marking note: Must state C and D AND explain with reference to the most recent common ancestor/node.

(b) Species E is the most distantly related to the other four species. [1 mark] Species E branched off from the common ancestor of all five species earliest (at the deepest/most basal node), meaning it shares the most distant common ancestor with the others. [1 mark]

Marking note: Must state E AND explain with reference to the earliest branching point.

(c) Molecular evidence such as comparing amino acid sequences of cytochrome c can be used to construct phylogenetic trees because: [3 marks]

Cytochrome c is a protein found in many organisms, and its amino acid sequence is determined by DNA [1 mark]
Mutations accumulate over time, leading to differences in the amino acid sequence; the more differences, the longer the time since two species diverged from a common ancestor [1 mark]
By comparing the number of amino acid differences between species, scientists can estimate evolutionary distances and construct branching diagrams (phylogenetic trees) showing probable evolutionary relationships [1 mark]

Marking note: Award marks for linking amino acid differences to mutation accumulation and divergence time, and explaining how this is used to infer relationships.

14. (a) A population of bacteria can develop resistance to an antibiotic through natural selection as follows: [4 marks]

Within a bacterial population, there is genetic variation; some bacteria may possess a mutation that gives them resistance to a specific antibiotic [1 mark]
When the antibiotic is applied, it kills susceptible bacteria, but resistant bacteria survive (differential survival) [1 mark]
The resistant bacteria reproduce, passing on the resistance allele to their offspring (differential reproduction) [1 mark]
Over many generations, the frequency of the resistance allele increases in the population, leading to a population that is largely resistant to the antibiotic [1 mark]

Marking note: Award marks for clear step-by-step explanation: variation → selection pressure → differential survival → differential reproduction → change in allele frequency.

(b) Two practices that can help reduce the spread of antibiotic resistance: [2 marks]

Practice 1: Prescribing antibiotics only when necessary / not prescribing antibiotics for viral infections [1 mark]
Practice 2: Completing the full course of antibiotics as prescribed / not stopping treatment early [1 mark]
Marking note: Accept other valid practices, e.g., reducing antibiotic use in agriculture, good hygiene practices to prevent infection, developing new antibiotics, using combination therapy. Award 1 mark for each valid practice.

15. Convergent evolution is the process where distantly related organisms independently evolve similar traits due to similar environmental pressures, not due to shared ancestry. Divergent evolution is the process where a common ancestral species evolves into two or more different species, with different traits, often due to different environmental pressures. [2 marks for definitions]

Example of convergent evolution: Wings of birds and wings of insects / streamlined body of sharks (fish) and dolphins (mammals) / any valid example. [1 mark]
Example of divergent evolution: Darwin's finches with different beak shapes / forelimbs of vertebrates (human, whale, bat) / any valid example. [1 mark]
Marking note: Award 1 mark for each correct definition (must contrast the two), and 1 mark for each correct example. Examples must be clearly linked to the correct type of evolution.

Section D: Data Analysis and Application Questions

16. (a) Adaptive radiation led to the diversity of beak shapes in Galapagos finches because: [3 marks]

A single ancestral finch species arrived on the Galapagos Islands and colonised different islands with different ecological niches / food sources (e.g., seeds, insects, cactus) [1 mark]
Finches with beak shapes that were better suited to the available food source on their island had a selective advantage and were more likely to survive and reproduce [1 mark]
Over many generations, natural selection led to the accumulation of different adaptations in different populations, resulting in the evolution of distinct species with different beak shapes adapted to their specific niches [1 mark]

Marking note: Award marks for linking common ancestry, different selective pressures, and divergence into different species.

(b) Any one type of evidence: [1 mark]

Comparing DNA sequences of the different finch species
Comparing amino acid sequences of proteins (e.g., cytochrome c)
Comparing embryonic development patterns
Comparing anatomical structures (e.g., homologous structures)
Marking note: Accept any valid type of evidence besides fossils.

17. (a) Gorilla is most closely related to humans. [1 mark] This is because gorilla haemoglobin has the fewest amino acid differences (1) compared to human haemoglobin, indicating the most recent common ancestor. [1 mark]

Marking note: Must state gorilla AND explain using data from the table.

(b) Species that are more distantly related have more amino acid differences in their haemoglobin because: [2 marks]

Mutations in the DNA coding for haemoglobin accumulate over time [1 mark]
The longer the time since two species diverged from a common ancestor, the more mutations have accumulated, leading to more differences in the amino acid sequence [1 mark]

Marking note: Award marks for linking mutation accumulation over time to genetic distance.

18. (a) Frequency of recessive allele (b):

Frequency of white rabbits (homozygous recessive, bb) = 16/100 = 0.16 = q² [1 mark]
Frequency of recessive allele (b) = q = √0.16 = 0.4 [1 mark]

Marking note: Award 1 mark for correct calculation of q², and 1 mark for correct calculation of q. Accept working in decimals or percentages.

(b) Two conditions for Hardy-Weinberg equilibrium: [2 marks]

No mutation
Random mating
No natural selection
Large population size (no genetic drift)
No gene flow / migration
Marking note: Award 1 mark for each correct condition, up to 2 marks.

19. (a) The trend shown in the graph is that the frequency of the pesticide resistance allele increases over time from Year 1 to Year 10. [1 mark] The increase is gradual at first, then becomes more rapid, before levelling off at a high frequency. [1 mark]

Marking note: Award 1 mark for describing the overall increase, and 1 mark for describing the shape of the curve (e.g., slow then rapid then plateau).

(b) The trend can be explained by natural selection: [3 marks]

Before the pesticide was introduced (Year 1), the resistance allele was present at a low frequency due to natural variation/mutation [1 mark]
When the pesticide was introduced (Year 2), it acted as a selective pressure, killing susceptible mosquitoes but allowing resistant mosquitoes to survive and reproduce [1 mark]
Over subsequent generations, the resistant mosquitoes passed on the resistance allele to their offspring, causing the frequency of the allele to increase rapidly in the population until most mosquitoes were resistant (plateau) [1 mark]

Marking note: Award marks for linking the introduction of the pesticide to differential survival and reproduction, and explaining the shape of the curve.

20. The statement "The theory of evolution is just a theory, not a fact" misunderstands the scientific meaning of the word "theory." [1 mark] In science, a theory is a well-substantiated explanation of some aspect of the natural world that is based on a body of facts, laws, and tested hypotheses. It is not a mere guess or speculation. [1 mark] The theory of evolution is supported by a vast body of evidence from multiple fields, including:

The fossil record, which shows transitional forms and changes in organisms over time [1 mark]
Comparative anatomy (homologous structures), which indicates common ancestry
Molecular biology (DNA and protein sequence comparisons), which shows genetic relationships between species
Biogeography, which shows patterns of species distribution consistent with evolution
Direct observation of evolution in action (e.g., antibiotic resistance in bacteria, peppered moth)
Marking note: Award 1 mark for explaining the scientific meaning of "theory," 1 mark for stating that evolution is supported by evidence, and up to 2 marks for providing specific examples of evidence (at least two distinct types of evidence required for full marks).

END OF ANSWER KEY