A4.2 Conservation of biodiversity
Practice exam-style IB Biology questions for Conservation of biodiversity, aligned with the syllabus and grouped by topic.
Question 1
What is genetic diversity?
A.
The variety of ecosystems present in a geographical region
B.
The number of ecological processes occurring in a habitat
C.
The number of different species and their relative abundance in a community
D.
The variety of alleles and genotypes within a species or population
Question 2
What is the most direct anthropogenic cause of extinction when organisms are removed faster than reproduction can replace them?
A.
Ecosystem succession
B.
Over-exploitation
C.
Adaptive radiation
D.
Temporal isolation
Question 3
What was the main anthropogenic driver of collapse of the Aral Sea ecosystem?
A.
Hunting of keystone marine mammals
B.
Introduction of a predatory fish species
C.
Acidification by volcanic gases
D.
Diversion of inflowing rivers for irrigation
Question 4
What is an example of in situ conservation?
A.
Storing seeds of a threatened plant in a seed bank
B.
Breeding an endangered frog in a zoo laboratory
C.
Keeping tissue samples from a rare tree in liquid nitrogen
D.
Protecting a coral reef community within a marine reserve
Question 5
Define species richness.
[1]
Distinguish between species diversity and ecosystem diversity.
[1]
Question 6
A single survey of a grassland records 18 plant species. Why is this insufficient evidence for a biodiversity decline?
A.
Change requires comparable repeated surveys over time
B.
Species richness cannot be measured in grassland ecosystems
C.
Only genetic diversity can be used as evidence of biodiversity change
D.
Citizen scientists cannot collect data used in biodiversity studies
Question 7
What is the overarching cause that increases demand for land, water, food, energy and materials in the current biodiversity crisis?
A.
Storage of germ plasm
B.
Human population growth
C.
Classification by splitters
D.
Peer review of published surveys
Question 8
What is the rationale for prioritizing EDGE species for conservation?
A.
They are species that reproduce rapidly in captivity
B.
They are both evolutionarily distinct and globally endangered
C.
They are common species that maintain high biomass in ecosystems
D.
They are species found only in national parks
Question 9
Two forest fragments have the same number of tree species. Fragment X has similar numbers of individuals in each species, whereas fragment Y is dominated by one species. Which statement is correct?
A.
Fragment X has lower species richness than fragment Y
B.
Fragment Y has higher ecosystem diversity than fragment X
C.
Fragment X has higher species evenness than fragment Y
D.
Fragment Y has higher genetic diversity than fragment X
Question 10
Why can drainage of peat swamp forest lead to long-term ecosystem loss?
A.
It prevents conversion to oil palm plantations
B.
It increases genetic diversity of dipterocarp trees
C.
It raises the water table and prevents decomposition
D.
It lowers the water table, increasing peat decomposition and fire risk
Question 11
A threatened tree has orthodox seeds that remain viable after drying and storage at low temperature. Which conservation approach is most directly described?
A.
Rewilding
B.
Nature reserve management
C.
Seed-bank storage of germ plasm
D.
Biological control by invasive species
Question 12
The North Island giant moa, Dinornis novaezealandiae, became extinct after human settlement of New Zealand.
State one anthropogenic pressure that contributed to its extinction.
[1]
Outline why large terrestrial megafauna can be especially vulnerable to over-exploitation.
[1]
Question 13
Explain how fertilizer leaching from farmland can cause loss of biodiversity in a freshwater ecosystem. [3]
Question 14
A conservation group counts butterflies along the same 1 km transect each June.
State why repeating the survey is important.
[1]
Outline two conditions that should be kept comparable between years.
[1]
Question 15
Compare in situ and ex situ conservation. [4]
Question 16
Outline why the number of species currently alive on Earth is an estimate rather than a known total. [3]
Question 17
A fixed quadrat survey was carried out in a meadow in 2010 and repeated using the same method in 2025.
| Species | 2010 / individuals | 2025 / individuals |
|---|---|---|
| Perennial ryegrass | 18 | 70 |
| White clover | 16 | 12 |
| Daisy | 17 | 10 |
| Common sorrel | 15 | 8 |
| Bird's-foot trefoil | 19 | 0 |
| Yarrow | 15 | 0 |
Identify the year with the higher species richness.
[1]
Describe the change in species evenness between the two years.
[1]
Suggest one reason why using the same quadrat size and season improves the validity of the comparison.
[1]
Question 18
A conservation agency recorded annual deaths of a marine mammal from hunting, fishing-gear entanglement and unknown causes before the species became locally extinct.
Identify the cause responsible for the largest number of recorded deaths.
[1]
State the total number of anthropogenic categories shown.
[1]
Suggest two conservation actions that could have reduced the risk of extinction.
[1]
Question 19
A taxonomist recognizes several genetically distinct island populations as separate species, although they look similar. What term best describes this taxonomic approach?
A.
Splitting
B.
Lumping
C.
Rewilding
D.
Reclamation
Question 20
A biodiversity survey based on a phone app has many records near roads but few records in remote areas. What is the main methodological concern?
A.
Species richness cannot be estimated from public observations
B.
Peer review cannot be used for citizen-science data
C.
Photographic validation always reduces sample size to zero
D.
Sampling effort is uneven across the study region
Question 21
In Simpson’s reciprocal index, D = N(N − 1) / Σn(n − 1), what change generally increases D?
A.
Counting only the most abundant species in the sample
B.
Higher richness and more even distribution of individuals among species
C.
The same total number of organisms concentrated in one species
D.
Lower richness and stronger dominance by one species
Question 22
A species is the only surviving member of an ancient clade but is not currently threatened. How would the EDGE programme treat it?
A.
It would be ranked only by its economic value
B.
It would be ignored because clades are not used in conservation
C.
It would automatically have high EDGE priority because it is evolutionarily distinct
D.
It would not be an EDGE species unless it is also globally endangered
Question 23
An introduced snake reaches an island without native mammalian predators and causes rapid decline of nesting birds. What mechanism best explains the native bird losses?
A.
Predation by an invasive alien species
B.
Loss of biodiversity by taxonomic lumping
C.
Pollution through nutrient enrichment
D.
Ex situ conservation of reptiles
Question 24
Why are estimates of total prokaryote species number especially uncertain?
A.
Prokaryotes have no genetic variation
B.
Classification is never used for bacteria
C.
Many prokaryotes cannot be cultured easily and species definitions are difficult
D.
All prokaryotes are extinct in the fossil record
Question 25
Explain how global transport contributes to the current biodiversity crisis. [4]
Question 26
Explain why conservation priorities such as EDGE require debate rather than being decided by science alone. [4]
Question 27
A quadrat sample contains 10 individuals of species A, 10 of species B and 20 of species C.
Using Simpson’s reciprocal index, D = N(N − 1) / Σn(n − 1):
Calculate N.
[1]
Calculate Σn(n − 1).
[1]
Calculate D to two significant figures.
[1]
Question 28
Citizen-science records show that a rare orchid has declined in one country. Suggest three features of the data collection that would make this evidence more reliable. [3]
Question 29
Explain why removal of a keystone species may cause ecosystem loss even if the species was not abundant. [4]
Question 30
A captive population of an endangered mammal has increased, but reintroduction success is low. Explain two limitations of relying only on ex situ conservation for this species. [3]
Question 31
Explain how roads through a tropical forest can cause interacting pressures on biodiversity. [4]
Question 32
Satellite images were used to estimate the area of mixed dipterocarp forest and oil palm plantation in a region of Southeast Asia.
Describe the trend in mixed dipterocarp forest area.
[1]
Describe the trend in oil palm plantation area.
[1]
Explain how conversion to oil palm plantation can cause ecosystem loss.
[1]
Question 33
A degraded river corridor was reclaimed by removing concrete banks, replanting native vegetation and reconnecting a floodplain. Biodiversity was surveyed for five years.
State the variable plotted on the y-axis.
[1]
Describe the overall change after reclamation.
[1]
Explain how two of the reclamation actions could increase biodiversity.
[1]
Question 34
A graph shows the number of records submitted to a citizen-science bird database and the estimated population size of one wetland bird over the same period.
Describe the trend in estimated population size.
[1]
Describe the trend in number of records submitted.
[1]
Explain why an increase in records submitted does not necessarily mean the species population increased.
[1]
Suggest one way to improve the reliability of the citizen-science evidence.
[1]
Question 35
Distinguish between the approaches of taxonomic splitters and lumpers, and state one conservation implication of this difference. [4]
Question 36
A drained wetland has lost most aquatic plants and amphibians. Suggest four management actions that could be used in reclamation of this ecosystem. [4]
Question 37
Compare prioritizing an EDGE species with prioritizing a keystone species for conservation. [4]
Question 38
A repeated survey recorded individuals of five fish species before and after river pollution control.
| Fish species | Before control / count | Post-control / count |
|---|---|---|
| Stone loach | 80 | 30 |
| Minnow | 15 | 20 |
| Bullhead | 5 | 20 |
| Chub | 0 | 15 |
| Dace | 0 | 15 |
| Total N | 100 | 100 |
Identify the survey with higher species richness.
[1]
Using the data provided, calculate Simpson’s reciprocal index for the post-control survey to two significant figures.
[1]
Explain what a higher Simpson’s reciprocal index indicates about the fish community.
[1]
Question 39
Four threatened mammals were assessed for conservation priority using evolutionary distinctness and global endangerment.
Identify the species with the highest EDGE priority from the data.
[1]
Explain why this species has high EDGE priority.
[1]
Suggest one reason why a conservation decision might still prioritize a different species.
[1]
Question 40
A port authority monitored the number of international ship arrivals and the cumulative number of established non-native marine species in a harbour.
Describe the relationship shown between ship arrivals and non-native species.
[1]
Suggest a mechanism by which global transport can introduce non-native species.
[1]
Explain why some introduced species become a biodiversity threat.
[1]
Suggest one management action to reduce future introductions.
[1]
Question 41
A government plans to conserve an endangered amphibian whose wetland habitat is polluted and fragmented.
Outline two reasons why in situ conservation is usually preferred.
[1]
Discuss why several conservation approaches may be needed for this amphibian.
[1]
Question 42
Human activities are causing many species extinctions in the current biodiversity crisis.
Define anthropogenic extinction.
[1]
Explain three anthropogenic causes of species extinction, using examples where appropriate.
[1]
Question 43
Reliable evidence is needed before concluding that a biodiversity crisis is occurring.
Outline two measurements that can be used as evidence of biodiversity change.
[1]
Evaluate the use of expert surveys and citizen-science records as evidence for a biodiversity crisis.
[1]
Question 44
Ecosystem loss can occur even when not all species in the ecosystem have become extinct.
Define ecosystem loss.
[1]
Explain anthropogenic causes of ecosystem loss, including one named case study.
[1]
Question 45
Two reserves for the same endangered antelope are compared. Reserve A is larger but isolated. Reserve B is smaller but connected to another habitat patch by a wildlife corridor.
State which reserve has the larger area.
[1]
Compare the likely effect of isolation on genetic diversity in the two reserves.
[1]
Evaluate one advantage and one limitation of relying on reserves alone for conserving this antelope.
[1]
Question 46
A phylogenetic study of an island lizard complex was interpreted by two taxonomic groups. Group 1 classified the populations as two species, while Group 2 classified them as five species.
Identify which group used the splitter approach.
[1]
State one type of evidence in the figure that could support recognizing more species.
[1]
Explain one conservation consequence of accepting Group 2’s classification.
[1]
Suggest why the same observations can lead to different classifications.
[1]
Question 47
Conservation resources are limited, so priorities must be set.
Outline the two criteria used in the EDGE of Existence programme.
[1]
Discuss the strengths and limitations of using EDGE as a basis for conservation prioritization.
[1]
Question 48
A long-term biodiversity monitoring programme uses both professional ecologists and trained volunteers.
Outline why repeated surveys are needed to provide evidence of biodiversity change.
[1]
Evaluate how the monitoring programme should be designed so that its conclusions are verifiable and reliable.
[1]
Question 49
The current biodiversity crisis is often described as the sixth mass extinction.
Outline the role of human population growth as an overarching pressure.
[1]
Discuss how different anthropogenic causes can interact to accelerate biodiversity loss.
[1]
Question 50
Biodiversity is a property of life at several levels of biological organization.
Outline two levels of biodiversity.
[1]
Compare and contrast how genetic diversity, species diversity and ecosystem diversity can contribute to the stability of ecological communities.
[1]
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