Biology • Year 11 • Module 3 • Lesson 9
Convergent, Divergent & Punctuated Equilibrium
Lock in the core vocabulary, the convergent/divergent distinction, analogous versus homologous structures, and the two models of evolutionary pace before moving to application tasks.
1. Complete the paragraph
Fill each blank with the correct term from the word bank. Use each term once only. 8 marks
When related species descended from a _______________ become increasingly different as they adapt to different niches, this is _______________ evolution. The structures they share have the same evolutionary origin but possibly different functions, so they are called _______________ structures. When unrelated species independently evolve similar features in similar environments, this is _______________ evolution, and the similar structures, which have different origins, are called _______________ structures. The rapid divergence of one ancestor into many species filling different niches is called _______________. The model that proposes slow, steady, continuous change over long periods is _______________, whereas the model that proposes long periods of stasis interrupted by short bursts of rapid change is _______________.
2. Term–definition match
Write the matching term from this list in the right-hand column: divergent evolution • convergent evolution • homologous structure • analogous structure • adaptive radiation • punctuated equilibrium • gradualism • common ancestor. 8 marks
| # | Definition | Matching term |
|---|---|---|
| 2.1 | Related species from a common ancestor becoming increasingly different over time. | |
| 2.2 | Unrelated species independently evolving similar features in similar environments. | |
| 2.3 | A structure with the same evolutionary origin but possibly different function. | |
| 2.4 | A structure with similar function but different evolutionary origin. | |
| 2.5 | Rapid divergence of one ancestor into many species filling different niches. | |
| 2.6 | A model of evolution with long periods of stasis interrupted by short bursts of rapid change. | |
| 2.7 | A model of evolution proposing slow, steady, continuous change over long periods. | |
| 2.8 | An ancestral species from which two or more later species descended. |
3. Classify the examples
For each example below, write C (convergent evolution) or D (divergent evolution) in the Type column. 8 marks
| Type (C/D) | Example |
|---|---|
| Sharks (fish) and dolphins (mammals) both have streamlined bodies for fast swimming | |
| Darwin's finches developing many different beak shapes from one ancestral finch | |
| The wings of a bird, a bat and an insect, all used for flight | |
| The pentadactyl (five-fingered) limb in humans, whales, bats and cats | |
| Australian marsupials radiating into gliders, carnivores and grazers | |
| The eye of an octopus and the camera-eye of a mammal | |
| Marsupial moles and placental moles both evolving burrowing forms | |
| Lake Victoria cichlids forming about 500 species from a single ancestor |
4. True or false, with correction
Circle T or F. If the statement is false, write the corrected version on the line below. 8 marks, 1 for T/F, 1 for correction where needed
4.1 Convergent evolution produces analogous structures in unrelated species facing similar selection pressures. T / F
4.2 If two animals look similar, they must always be closely related. T / F
4.3 Punctuated equilibrium describes long periods of stasis interrupted by short bursts of rapid change. T / F
4.4 Gradualism and punctuated equilibrium are mutually exclusive, so only one of them can ever be correct. T / F
5. Build a concept map
Draw labelled arrows between the five terms below to show how they connect. Each arrow must carry a linking phrase (e.g. “produces”, “is evidence of”, “is a rapid form of”). Aim for at least 5 labelled arrows. 5 marks
Supplied terms: divergent evolution • convergent evolution • homologous structures • analogous structures • adaptive radiation.
Q1, Cloze paragraph
In order: common ancestor • divergent • homologous • convergent • analogous • adaptive radiation • gradualism • punctuated equilibrium.
Q2, Term–definition matches
2.1 divergent evolution • 2.2 convergent evolution • 2.3 homologous structure • 2.4 analogous structure • 2.5 adaptive radiation • 2.6 punctuated equilibrium • 2.7 gradualism • 2.8 common ancestor.
Q3, Classification answers
C Sharks and dolphins • D Darwin's finches • C Bird, bat and insect wings • D Pentadactyl limb • D Marsupial radiation • C Octopus and mammal eye • C Marsupial and placental moles • D Lake Victoria cichlids.
Q4, True/False with correction
4.1 True.
4.2 False. Correction: Similar appearance can result from convergent evolution (analogous structures) in unrelated species facing the same selection pressures, so it does not always mean close relationship. Shared ancestry is shown by homologous structures, not surface resemblance.
4.3 True.
4.4 False. Correction: Gradualism and punctuated equilibrium are not mutually exclusive, the fossil record shows both patterns in different lineages, so both can operate.
Q5, Sample concept map
Accept any biologically valid linking phrases. A correct map should include arrows such as:
- divergent evolutionproduces → homologous structures
- convergent evolutionproduces → analogous structures
- adaptive radiationis a rapid form of → divergent evolution
- homologous structuresare evidence of → divergent evolution (shared ancestry)
- analogous structuresare evidence of → convergent evolution (similar selection pressures)
Award 1 mark per correctly labelled arrow with a valid linking phrase. Maximum 5 marks.