Biology • Year 11 • Module 4 • Lesson 16
Biodiversity — Measurement, Importance and Ecosystem Stability
Lock in the three levels of biodiversity, how each is measured, and the core vocabulary of ecosystem services and stability before moving to application tasks.
1. Sort examples into the three levels of biodiversity
Below are eight examples. Write each letter into the correct column of the table. 8 marks
Examples (A–H)
A — The existence of floodplain forest, wetland, and dryland woodland in the Murray-Darling Basin
B — Variation in allele frequencies between populations of Eastern grey kangaroos
C — A forest containing 120 bird species
D — Tasmanian devils having low variation at immune-system gene loci due to a historical bottleneck
E — The presence of mangrove, saltmarsh, and open-water zones within an estuary
F — A grassland where 10 plant species each make up roughly 10% of individuals
G — Loss of wetland area in the Murray-Darling reducing habitat variety by over 50%
H — Different coat-colour alleles present in a population of dingoes
| Genetic diversity | Species diversity | Ecosystem diversity |
|---|---|---|
2. Term–definition match
Match each definition (1–10) with one term from the box below. Write the term in the right-hand column. 10 marks
Terms: biodiversity • genetic diversity • species diversity • ecosystem diversity • species richness • species evenness • Simpson’s Diversity Index • functional redundancy • resilience • ecosystem services
| # | Definition | Term |
|---|---|---|
| 2.1 | The total variety of life on Earth, measured at genetic, species, and ecosystem levels. | |
| 2.2 | Variation in allele frequencies within a population or species. | |
| 2.3 | The number and relative abundance of species in a community. | |
| 2.4 | The variety of habitat types, communities, and ecological processes within a region. | |
| 2.5 | The total number of different species present in a community. | |
| 2.6 | How evenly individuals are distributed across the species in a community. | |
| 2.7 | A statistical measure combining richness and evenness; a higher value indicates greater diversity. | |
| 2.8 | The situation where multiple species perform the same ecological function, buffering the ecosystem against species loss. | |
| 2.9 | The ability of an ecosystem to resist disruption and recover after disturbance. | |
| 2.10 | The benefits that ecosystems provide to humans, including provisioning, regulating, and cultural benefits. |
3. True or false — with correction
Circle T or F for each statement. If the statement is false, write the corrected version on the line below it. 10 marks (1 for T/F; 1 for each correction)
3.1 Species richness and species evenness are the same thing. T / F
3.2 High genetic diversity increases a population’s ability to respond to a new disease because more individuals are likely to carry resistance alleles. T / F
3.3 Ecosystem services are limited to the food and timber that ecosystems provide. T / F
3.4 A community with 10 species where each represents exactly 10% of individuals has higher evenness than one with 10 species where one species makes up 90% of individuals. T / F
3.5 Functional redundancy means that some species have no ecological function and are unnecessary in an ecosystem. T / F
4. Classify ecosystem services
The lesson identifies three categories of ecosystem service: provisioning, regulating, and cultural. Write the correct category beside each example. 8 marks
| # | Service example | Category |
|---|---|---|
| 4.1 | Bees pollinating crops that produce fruit for human consumption | |
| 4.2 | Wetland plants filtering pollutants from river water before it reaches the sea | |
| 4.3 | Timber harvested from forests for building material | |
| 4.4 | Indigenous Australians using Country for spiritual ceremonies and cultural identity | |
| 4.5 | Coastal mangroves absorbing wave energy during storm surges, reducing flood damage | |
| 4.6 | Native plants providing medicinal compounds used to develop new pharmaceuticals | |
| 4.7 | Scientists conducting biodiversity research in national parks | |
| 4.8 | Forests storing carbon dioxide from the atmosphere, reducing greenhouse gas concentrations |
5. IUCN Red List — sequence and apply
5.1 Write the seven IUCN Red List categories in order from lowest risk to highest risk (or gone). 4 marks (0.5 per correct position)
| Position (lowest risk first) | IUCN category |
|---|---|
| 1 (lowest risk) | |
| 2 | |
| 3 | |
| 4 | |
| 5 | |
| 6 | |
| 7 (gone) |
5.2 The thylacine (Tasmanian tiger) was last seen in captivity in 1936. Which IUCN category applies to it today? Explain your choice in one sentence. 2 marks
5.3 The greater bilby is currently listed as Vulnerable. What does this mean about its extinction risk relative to a species listed as Endangered? 2 marks
Q1 — Three-level sort
Genetic diversity: B, D, H
Species diversity: C, F
Ecosystem diversity: A, E, G
Award 1 mark per correct letter (max 8). Award 0 for any letter placed in the wrong column. Accept brief justification where provided.
Q2 — Term–definition matches
2.1 biodiversity • 2.2 genetic diversity • 2.3 species diversity • 2.4 ecosystem diversity • 2.5 species richness • 2.6 species evenness • 2.7 Simpson’s Diversity Index • 2.8 functional redundancy • 2.9 resilience • 2.10 ecosystem services
Q3 — True / false with correction
3.1 False. Correction: Species richness is the total number of species present; species evenness is how uniformly individuals are distributed across those species. They are different components of species diversity.
3.2 True.
3.3 False. Correction: Ecosystem services are divided into three categories — provisioning (e.g. food, timber), regulating (e.g. pollination, carbon storage, flood mitigation), and cultural (e.g. recreation, scientific research, Indigenous heritage).
3.4 True. Equal distribution of individuals across species = maximum evenness.
3.5 False. Correction: Functional redundancy refers to multiple species performing the same ecological function, buffering the ecosystem against species loss. No implication that any species is unnecessary — rather, the redundancy means the function continues if one species is lost.
Award 1 mark per correct T/F; 1 mark per acceptable correction for each false statement (max 5 corrections × 1 = 5). Total: 10 marks.
Q4 — Ecosystem services categories
4.1 Regulating (pollination) • 4.2 Regulating (water purification) • 4.3 Provisioning (timber) • 4.4 Cultural (spiritual / heritage) • 4.5 Regulating (flood mitigation) • 4.6 Provisioning (medicine) • 4.7 Cultural (scientific research) • 4.8 Regulating (carbon storage)
Award 1 mark per correct category (max 8). Accept “supporting” where a student argues nutrient cycling role — the lesson’s three categories are provisioning, regulating, and cultural; accept any defensible classification with brief justification.
Q5.1 — IUCN sequence
1. Least Concern → 2. Near Threatened → 3. Vulnerable → 4. Endangered → 5. Critically Endangered → 6. Extinct in the Wild → 7. Extinct
Award 0.5 per correct position (max 4). Deduct 0.5 for each transposed adjacent pair. Order must be correct; capitalisation not penalised.
Q5.2 — Thylacine category
Extinct. The thylacine has not been sighted since 1936 and no viable population exists anywhere; it meets the IUCN criterion for extinction (no reasonable doubt that the last individual has died). Award 1 mark for correct category; 1 mark for a reason linking to absence of any surviving individuals.
Q5.3 — Vulnerable vs Endangered
Vulnerable indicates a lower extinction risk than Endangered. The greater bilby faces a high risk of extinction, but the criteria for rate of decline, population size, and range restriction have not yet been met at the level required for Endangered status. An Endangered species meets stricter (more severe) threshold criteria, indicating it faces a very high risk of extinction in the wild. Award 1 mark for correctly identifying Vulnerable as lower-risk than Endangered; 1 mark for linking to differences in rate-of-decline / population size thresholds.