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A Level H1 Biology Evolution Diversity Quiz

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Questions

A-Level Biology H1 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 clear scientific terminology and refer to specific biological principles where appropriate.

Section A: Multiple Choice & Short Concepts (10 Marks)

1. Which of the following best describes the mechanism of natural selection?
[1]
A. Organisms develop traits during their lifetime to suit the environment and pass them on.
B. Environmental changes cause mutations that help organisms survive.
C. Individuals with advantageous alleles are more likely to survive and reproduce.
D. The strongest individuals in a population always survive predation.

Answer: __________________________

2. The wings of a bat and the wings of a butterfly are structurally different but serve the same function. This is an example of:
[1]
A. Homologous structures
B. Analogous structures
C. Vestigial structures
D. Convergent evolution via common ancestry

Answer: __________________________

3. Which of the following provides the strongest evidence for the recent common ancestry of humans and chimpanzees?
[1]
A. Similarity in skeletal structure
B. Similarity in DNA base sequences
C. Presence of similar embryonic gill slits
D. Similarity in protein function

Answer: __________________________

4. In a population of beetles, the allele for green colour (G) is dominant to the allele for brown colour (g). If the frequency of the brown phenotype is 0.16, what is the frequency of the dominant allele (G) assuming Hardy-Weinberg equilibrium?
[2]

Working:
 
Answer: __________________________

5. Define the term speciation.
[2]

Answer:

6. State two conditions required for the Hardy-Weinberg principle to apply to a population.
[2]

7. Explain why genetic drift has a greater effect on small populations than on large populations.
[2]

Answer:

8. Methicillin-resistant Staphylococcus aureus (MRSA) is a strain of bacteria resistant to many antibiotics. Explain, using the principles of natural selection, how a population of S. aureus becomes resistant to methicillin.
[4]

Answer:

9. Suggest why doctors are advised to prescribe a combination of antibiotics rather than a single antibiotic for severe bacterial infections.
[2]

Answer:

10. Fig. 1 shows the forelimb bones of a human, a bat, and a whale. State the term used to describe structures that have a similar anatomical origin but different functions.
[1]

(Note: Imagine Fig. 1 displays the humerus, radius, ulna, carpals, metacarpals, and phalanges for all three mammals, arranged in similar positional patterns but different proportions.)

Answer: __________________________

Section B: Structured Response & Data Interpretation (18 Marks)

11. Explain how the structure of the whale’s flipper supports the theory of evolution from a terrestrial ancestor.
[3]

Answer:

12. Contrast the evolutionary process that led to the whale’s flipper with the process that led to the streamlined body shape of a shark (a fish).
[2]

Answer:

13. Cytochrome c is a protein involved in cellular respiration. Explain why cytochrome c is suitable for studying evolutionary relationships across a wide range of species.
[2]

Answer:

14. The table below shows the number of amino acid differences in cytochrome c between humans and other organisms.

Organism	Number of Amino Acid Differences from Human
Chimpanzee	0
Rhesus Monkey	1
Horse	12
Tuna Fish	21
Yeast	45

Using the data, deduce which organism is most closely related to humans and explain your reasoning.
[2]

Answer:

15. A student claims that because humans and yeast both have cytochrome c, they must have a recent common ancestor. Evaluate this statement.
[2]

Answer:

16. Describe how geographical isolation can lead to the formation of new species (allopatric speciation).
[6]

Answer:

Section C: Extended Response & Synthesis (12 Marks)

17. Explain how reproductive isolation mechanisms maintain species distinctness even if the geographical barriers are removed. Include examples of pre-zygotic barriers.
[3]

Answer:

18. Explain how reproductive isolation mechanisms maintain species distinctness even if the geographical barriers are removed. Include examples of post-zygotic barriers.
[3]

Answer:

19. Distinguish between convergent evolution and divergent evolution, providing one biological example for each.
[4]

Answer:

20. Discuss the role of mutation in providing the raw material for evolution.
[2]

Answer:

Answers

A-Level Biology H1 Quiz - Evolution Diversity (Answer Key)

Total Marks: 40

Section A: Multiple Choice & Short Concepts

1. C
[1 mark]
Reasoning: Natural selection acts on existing variation; individuals with advantageous traits survive/reproduce more, passing on alleles. A is Lamarckian; B implies environment causes specific helpful mutations (incorrect); D is too vague/incorrect (strength isn't the only factor).

2. B
[1 mark]
Reasoning: Analogous structures have similar functions but different evolutionary origins (convergent evolution). Homologous structures share ancestry.

3. B
[1 mark]
Reasoning: DNA base sequence comparison is the most direct and precise measure of genetic relatedness.

4. 0.6
[2 marks]
Working:

Frequency of recessive phenotype ( $q^2$ ) = 0.16.
Frequency of recessive allele ( $q$ ) = $\sqrt{0.16} = 0.4$ .
Frequency of dominant allele ( $p$ ) = $1 - q = 1 - 0.4 = 0.6$ .
[1 mark for correct working/logic, 1 mark for final answer]

5. Speciation is the evolutionary process by which populations evolve to become distinct species.
[2 marks]
Key points:

Formation of new species [1]
From an existing population [1]
Usually involves reproductive isolation.

6. Any two of the following:
[2 marks, 1 each]

No mutation
No migration (gene flow)
Large population size (no genetic drift)
Random mating
No natural selection

7. In small populations, chance events (such as the death of a few individuals) can significantly alter allele frequencies.
[2 marks]
Key points:

Allele frequencies change due to chance/random sampling error [1]
Effect is magnified because the sample size is small / loss of alleles is more impactful [1]

Variation exists in the bacterial population due to random mutation [1].
Some bacteria possess an allele for resistance to methicillin [1].
When exposed to methicillin, non-resistant bacteria die, while resistant bacteria survive (selection pressure) [1].
Resistant bacteria reproduce and pass the resistance allele to offspring, increasing its frequency in the population [1].

Different antibiotics target different bacterial mechanisms/pathways [1].
It reduces the probability that a bacterium will have simultaneous mutations conferring resistance to all drugs used [1].

10. Homologous structures
[1 mark]

Section B: Structured Response & Data Interpretation

11.

The whale flipper contains the same bone structure (humerus, radius, ulna, etc.) as terrestrial mammals [1].
This suggests they share a common ancestor that had limbs for walking on land [1].
Over time, natural selection modified the limb shape for swimming, but the underlying skeletal pattern remained [1].

12.

Whale flipper: Divergent evolution from a common tetrapod ancestor (homologous) [1].
Shark body: Convergent evolution; sharks and whales do not share a recent common ancestor with this trait, but evolved similar shapes due to similar aquatic environments [1].

13.

Cytochrome c is essential for aerobic respiration, so it is found in almost all eukaryotes [1].
It evolves slowly, allowing comparisons between distantly related species [1].

14.

Chimpanzee [1].
It has zero amino acid differences, indicating the most recent common ancestor and highest genetic similarity [1].

15.

The statement is incorrect regarding "recent" [1].
While they share a common ancestor (evidenced by the presence of the protein), the large number of differences (45) indicates the ancestor lived a very long time ago [1].

16. Allopatric Speciation (6 marks)
Marking Guide:

Geographical Barrier: A physical barrier (e.g., ocean, mountain range) separates a single population into two or more isolated populations [1].
No Gene Flow: The separated populations cannot interbreed, preventing the exchange of alleles [1].
Different Selection Pressures: The environments in the separated areas differ (e.g., climate, food sources, predators) [1].
Natural Selection: Individuals with alleles advantageous in their specific environment survive and reproduce more successfully [1].
Genetic Drift/Mutation: Random mutations occur independently in each population; genetic drift may alter allele frequencies, especially if populations are small [1].
Accumulation of Differences: Over time, genetic and phenotypic differences accumulate to the point where the populations are distinct [1].

Section C: Extended Response & Synthesis

17. Pre-zygotic Barriers (3 marks)
Marking Guide:

Definition: Mechanisms that prevent fertilization from occurring [1].
Example 1: Temporal isolation (breeding at different times/seasons) OR Behavioral isolation (different courtship rituals) [1].
Example 2: Mechanical isolation (physical incompatibility) OR Ecological isolation (different habitats) [1].

18. Post-zygotic Barriers (3 marks)
Marking Guide:

Definition: Mechanisms that operate after fertilization has occurred [1].
Example 1: Hybrid inviability (hybrid zygote fails to develop or dies early) [1].
Example 2: Hybrid sterility (hybrid survives but is sterile, e.g., mule), preventing gene flow back into parent populations [1].

19.

Divergent Evolution: Related species evolve different traits due to different environments. Example: Darwin's finches or whale flipper vs. human hand [2].
Convergent Evolution: Unrelated species evolve similar traits due to similar environments. Example: Shark body shape vs. Dolphin/Whale body shape or Bat wing vs. Butterfly wing [2].

20.

Mutations are random changes in DNA sequence that create new alleles/genetic variation [1].
Without this variation, natural selection would have no raw material to act upon, preventing adaptation and evolution [1].