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O Level Biology Evolution Diversity Quiz

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O Level Biology AI Generated Generated by Qwen3.6 Plus Updated 2026-08-17

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Questions

O-Level Biology Quiz - Evolution Diversity

Name: ________________________
Class: ________________________
Date: ________________________
Score: ______ / 40

Duration: 45 minutes
Total Marks: 40

Instructions:

Answer all questions.
Write your answers in the spaces provided.
The number of marks is indicated in brackets [ ] at the end of each question or part question.
Use biological terminology accurately.

Section A: Multiple Choice (Questions 1–5)

Choose the correct answer and write the letter in the box provided.

1. Which of the following best defines evolution?
A. The change in an individual organism’s characteristics during its lifetime.
B. The gradual change in the inherited characteristics of a population over time.
C. The process by which organisms become perfectly adapted to their environment.
D. The sudden appearance of new species due to environmental changes.

Answer: [ ] [1]

2. In the context of natural selection, what is the primary source of variation within a population?
A. Environmental changes
B. Mutation
C. Competition for resources
D. Differential survival

Answer: [ ] [1]

3. Which of the following is an example of discontinuous variation?
A. Height in humans
B. Weight in dogs
C. Blood group in humans
D. Leaf surface area in oak trees

Answer: [ ] [1]

4. Antibiotic resistance in bacteria is an example of evolution by natural selection. Which statement correctly describes the process?
A. Antibiotics cause mutations in bacteria that make them resistant.
B. Bacteria learn to survive in the presence of antibiotics and pass this skill to offspring.
C. Resistant bacteria survive antibiotic treatment and reproduce, passing the resistance gene to offspring.
D. All bacteria in a population become resistant simultaneously when exposed to antibiotics.

Answer: [ ] [1]

5. Two populations of the same species are separated by a mountain range. Over time, they become unable to interbreed. This is an example of:
A. Artificial selection
B. Speciation
C. Genetic engineering
D. Continuous variation

Answer: [ ] [1]

Section B: Structured Questions (Questions 6–15)

6. Define the term natural selection.

[2]

7. Distinguish between continuous and discontinuous variation. Give one example for each.
Continuous Variation:

Example: ________________________
Discontinuous Variation:

Example: ________________________
[4]

8. Explain how mutation contributes to evolution.

[2]

9. The peppered moth (Biston betularia) exists in two forms: light-colored and dark-colored. During the Industrial Revolution, tree trunks became covered in soot.
(a) Explain why the population of dark-colored moths increased in industrial areas.

[3]

(b) If pollution controls were introduced and tree trunks became clean again, predict what would happen to the moth population. Explain your answer.

[2]

10. Describe the role of competition in natural selection.

[2]

11. State two factors, other than mutation, that can cause variation in a population.

[2]

12. Explain why evolution is described as a gradual process.

[2]

13. A farmer selects only the largest cows for breeding. Over several generations, the average size of the herd increases.
(a) Name this type of selection.

[1]

(b) How does this differ from natural selection?

[2]

14. The graph below shows the distribution of heights in a human population.

Image pending generation for this question.

(Imagine a bell-shaped curve)
(a) What type of variation is shown?

[1]

(b) Suggest one environmental factor that could affect an individual’s height.

[1]

15. Explain the concept of survival of the fittest in biological terms.

[2]

Section C: Free Response Questions (Questions 16–20)

16. Describe the steps involved in natural selection leading to the evolution of a new trait in a population.

[4]

17. Explain how the overuse of antibiotics has led to the emergence of "superbugs" (MRSA). Use the principles of natural selection in your answer.

[4]

18. Compare and contrast artificial selection and natural selection. Provide one example for each.

[4]

19. Discuss the importance of genetic variation for the survival of a species when the environment changes.

[4]

20. A species of bird lives on an island with two types of seeds: small, soft seeds and large, hard seeds. Birds with small beaks eat small seeds; birds with large beaks eat large seeds. Birds with medium beaks struggle to eat either.
(a) Predict how the bird population might change over time if the supply of small and large seeds remains abundant, but medium-sized seeds are scarce.

[2]

(b) Name this specific pattern of natural selection.

[1]

(c) Explain how this could eventually lead to speciation.

[3]

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Answers

O-Level Biology Quiz - Evolution Diversity: Answer Key

Total Marks: 40

Section A: Multiple Choice

1. B
Explanation: Evolution is defined as the change in inherited characteristics of a population over generations, not changes in an individual (A) or sudden appearances (D).

2. B
Explanation: Mutation is the primary source of new genetic variation. Environmental changes (A) select for variation but do not create it.

3. C
Explanation: Blood group is discontinuous (distinct categories). Height, weight, and leaf area are continuous (range of values).

4. C
Explanation: Natural selection acts on existing variation. Resistant bacteria survive and reproduce. Antibiotics do not cause the mutation (A), and bacteria do not "learn" (B).

5. B
Explanation: When populations can no longer interbreed, they have become separate species (speciation).

Section B: Structured Questions

6. Define natural selection. [2]

Process by which organisms better adapted to their environment tend to survive and produce more offspring. [1]
Over time, this leads to a change in the characteristics of the population. [1]

7. Distinguish between continuous and discontinuous variation. [4]

Continuous: Shows a range of values with no distinct categories; usually influenced by multiple genes and environment. [1]
Example: Height / Weight / Skin color. [1]
Discontinuous: Distinct categories with no intermediates; usually controlled by a single gene or few genes. [1]
Example: Blood group / Eye color (specific types) / Gender. [1]

8. How mutation contributes to evolution. [2]

Mutations are random changes in DNA sequence. [1]
They create new alleles/variations, some of which may provide a survival advantage and be passed on. [1]

9. Peppered Moth. [5]
(a) Increase in dark moths. [3]

Soot darkened tree trunks, making light moths visible to predators. [1]
Dark moths were camouflaged and less likely to be eaten. [1]
Dark moths survived to reproduce and pass on the dark allele. [1]
(b) Prediction if clean. [2]
Population of light-colored moths would increase. [1]
Light moths would be better camouflaged on clean trees, surviving predation better than dark moths. [1]

10. Role of competition. [2]

Resources (food, space, mates) are limited. [1]
Individuals with advantageous traits compete more successfully, survive, and reproduce. [1]

11. Other factors causing variation. [2]

Sexual reproduction (mixing of gametes/meiosis). [1]
Environmental factors (diet, climate, accidents). [1]

12. Why evolution is gradual. [2]

Changes in allele frequency occur over many generations. [1]
Accumulation of small advantageous traits takes a long time to result in significant change. [1]

13. Farmer selecting cows. [3]
(a) Name. [1]

Artificial selection.
(b) Difference. [2]
Artificial selection is driven by human choice for desired traits. [1]
Natural selection is driven by environmental pressures/survival. [1]

14. Height Graph. [2]
(a) Type. [1]

Continuous variation.
(b) Environmental factor. [1]
Diet / Nutrition / Illness during childhood.

15. Survival of the fittest. [2]

"Fittest" refers to organisms best adapted to their specific environment. [1]
These individuals are more likely to survive and reproduce, passing on their genes. [1]

Section C: Free Response Questions

16. Steps in natural selection. [4]

Variation: Individuals in a population show variation in traits (due to mutation/sexual reproduction). [1]
Competition/Struggle: There is a struggle for survival due to limited resources or predation. [1]
Selection: Individuals with advantageous traits are more likely to survive and reproduce. [1]
Inheritance: Advantageous alleles are passed to offspring, increasing their frequency in the next generation. [1]

17. Antibiotics and Superbugs. [4]

Bacterial populations have natural variation; some have mutations for resistance. [1]
When antibiotics are used, non-resistant bacteria die, but resistant ones survive. [1]
Resistant bacteria reproduce and pass the resistance gene to offspring. [1]
Overuse of antibiotics increases the selection pressure, leading to a population dominated by resistant strains (superbugs). [1]

18. Artificial vs Natural Selection. [4]

Agent: Natural selection is driven by environment; Artificial by humans. [1]
Goal: Natural selection aims for survival/reproduction; Artificial aims for human-desired traits (which may not aid survival). [1]
Speed: Artificial selection is often faster. [1]
Examples: Natural: Peppered moth / Giraffe neck length. Artificial: Dog breeds / Crop plants. [1] (Any valid comparison + examples).

19. Importance of genetic variation. [4]

Variation ensures some individuals possess traits suitable for new environmental conditions. [1]
If the environment changes (e.g., new disease, climate change), individuals without advantageous traits may die. [1]
Those with advantageous traits survive and reproduce. [1]
Without variation, the entire population might be susceptible to the same threat, leading to extinction. [1]

20. Bird Beaks and Speciation. [6]
(a) Prediction. [2]

The population will split into two groups: one with small beaks and one with large beaks. [1]
Birds with medium beaks will decrease in number due to lower survival rates. [1]
(b) Name. [1]
Disruptive selection.
(c) Speciation. [3]
Over time, the two groups may stop interbreeding (reproductive isolation). [1]
Accumulation of different genetic changes in each group. [1]
Eventually, they become distinct species unable to produce fertile offspring together. [1]