Biodiversity
Biodiversity — Comprehensive Study Pack
Summary
This module focuses mainly on water quality, with additional topics on sediments, air quality and greenhouse gases. By the end of the module, students should understand the chemical composition of freshwater, know which chemical analyses are needed for environmental investigations, understand analytical methods and instruments, recognise sources of error, and interpret chemical data using environmental standards and regulations. Understanding quality control, standard error, confidence intervals and detection limits is also important.
The module has a strong practical and career-focused element. Students will complete risk assessments, field sampling, water-quality analyses, sediment work, titrations and data analysis. Fieldwork requires suitable clothing, footwear and rain gear, while laboratory work requires a lab coat. Students are expected to become increasingly independent and engaged, reflecting the higher expectations of third- and fourth-year study.
Assessment consists of a 25% practical exam, a water-quality report, and a 50% final exam. The practical exam tests knowledge and skills from the laboratory sessions. The water-quality report uses data collected across campus: students combine class data but write an individual report, interpreting parameters such as nitrate and phosphate and comparing results with relevant thresholds. The final exam tests understanding of the course material and provides formulas/relevant reference information where needed.
Chemical analysis is needed to identify pollutants, determine environmental quality, assess health risks, investigate nutrient levels and understand how pollutants affect organisms and ecosystems. What is analysed depends on the (REPORA) research question, environmental conditions, pollutants of concern, organisms present, regulations and available resources. For example, excess algae may indicate high nutrient concentrations such as nitrate or phosphate.
There are several limitations to environmental monitoring. These include (CSAIBCP)cost, limited numbers of samples, accessibility, instrument sensitivity and detection limits, biological significance of measured concentrations, interactions between chemicals, and missing pollution events. A pollutant released between sampling times may be missed, so sampling frequency and timing are important.
Major contaminants discussed include nutrients such as nitrate and phosphate, inorganic ions and metals, organic pollutants such as hydrocarbons, PCBs and dioxins, organometallic compounds such as methylmercury, and naturally produced biotoxins. Some organic pollutants can accumulate in fatty tissues and biomagnify through food chains. Harmful algal blooms can also produce toxins that accumulate in shellfish and potentially affect humans.
Sampling must represent the material being studied in both time and space. Spatial sampling compares different locations, while temporal sampling examines changes over time. Sampling locations should be chosen according to the study objective, accessibility, safety, pollution sources, species of interest and available budget. Reference or baseline sites are particularly important when assessing the effect of a pollution source. For example, an upstream site can be compared with downstream sites near an effluent discharge.
Before field sampling, researchers should conduct reconnaissance/scoping, examine maps and access routes, consider environmental conditions such as high or low water flow, and complete a risk assessment. Diffuse pollution, such as agricultural runoff, may require multiple sampling locations because the pollution comes from a large area rather than one obvious point source.
The campus investigation involves sampling streams, lakes and ponds, measuring field parameters and analysing samples for substances including nitrate, nitrite and phosphate. The class data will be combined to assess campus water quality, identify pollutants of concern and suggest possible mitigation measures where necessary. Students should also become familiar with the campus water bodies and observe their condition before sampling.
Finally, the skills from this module are relevant to careers in environmental monitoring, the EPA, environmental consultancy, ecology and other environmental agencies. Water-quality monitoring is important because legislation such as the EU Water Framework Directive requires water quality to be assessed and reported.
2. Structured bullet-point summary
A. Core meaning of biodiversity
Biodiversity means the variety of living organisms.
It includes more than the number of species.
Three important levels are:
Species diversity: variety of species.
Ecological diversity: variety of habitats and ecosystems.
Genetic diversity: variation in genes and gene combinations.
Examples of different habitats:
Lakes
Rivers
Forests
Savannas
Wetlands
Coastal environments
Coral reefs
Biodiversity also includes:
Species interactions
Ecological processes
Genetic differences between populations
Habitat complexity
B. Ecological niches
A niche concerns what an organism can potentially do within its environment.
The realised niche is influenced by:
Competition
Predation
Parasitism
Food availability
Habitat conditions
Other species interactions
Organisms may not use all the resources or spaces they could theoretically use.
Different habitats contain different niches.
Habitat complexity creates more opportunities for specialisation.
C. Species interactions
Important interactions include:
Predation
Herbivory
Parasitism
Competition
Symbiosis
Predation:
One organism consumes another.
Herbivory:
Animals feed on plants or algae.
Parasitism:
One organism benefits while the host is harmed.
Hyperparasitism:
A parasite is itself parasitised.
Symbiosis:
Close interaction between different species.
Interactions form complex ecological networks.
D. Genetic diversity
Genetic diversity is variation in genes within a species.
It is often stored within separate populations.
Populations may become genetically distinct through:
Geographic isolation
Limited gene flow
Local adaptation
Different environmental conditions
Brown trout populations in different rivers may differ genetically.
Atlantic salmon populations from different regions may differ in:
Genes
Gene combinations
Chromosome characteristics
Conservation should protect:
Species
Populations
Genetic variability
“Same species” does not mean genetically identical.
E. Farmed versus wild salmon
Farmed Atlantic salmon have been selected for:
Fast growth
Delayed maturity
Efficient production of edible flesh
Desirable flesh colour
These traits are useful in aquaculture.
Farmed salmon may not survive well in the wild because they were not selected for:
Predator avoidance
Natural food searching
Migration
Competition
Variable environmental conditions
The example demonstrates the importance of population-level genetic differences.
F. Global distribution of biodiversity
Biodiversity is not evenly distributed across Earth.
Large isolated landmasses may contain unique organisms.
Australia contains distinctive organisms such as:
Kangaroos
Koalas
Terrestrial biodiversity is generally highest in the tropics.
Tropical biodiversity is associated with:
Climatic stability
Long evolutionary timescales
High habitat complexity
Many ecological niches
Polar regions experienced repeated ice ages.
Ice ages reduced or displaced biodiversity in many northern and southern regions.
Speciation requires long periods of time.
G. Tropical and marine diversity
Tropical rainforests contain very high species diversity.
Tropical forests have complex three-dimensional structures.
A single tree may contain:
Lichens
Insects
Flowers
Fungi
Birds
Other organisms
Biodiversity is not the same as biomass.
Marine diversity is high in:
Tropical waters
Coastal areas
Island-rich regions
Coral reefs
Shallow waters
Structurally complex habitats
Coral reefs create:
Crevices
Sheltered spaces
Nursery areas
Many specialised niches
Open-ocean regions may have low diversity because of:
Low nutrient availability
Low productivity
Lack of complex physical structure
H. Microbial biodiversity
Much of Earth’s biodiversity is microbial.
Bacteria and archaea contain enormous genetic diversity.
Archaea were historically grouped with bacteria but are now recognised as a separate major group.
Humans often underestimate microbial diversity because microorganisms are invisible.
Cyanobacteria:
Produced oxygen through photosynthesis.
Changed Earth’s atmosphere.
Helped create conditions for oxygen-using organisms.
Humans are ecosystems for microbes.
Different body regions support different microbial communities.
The lecturer described humans as:
Walking ecosystems
Walking habitats
I. Ecosystem services
Provisioning services
Food
Wood
Water
Oxygen
Crops
Fisheries
Other renewable resources
Regulating services
Climate regulation
Carbon movement
Pest control
Regulation of environmental conditions
Potential ocean carbon pumping by mesopelagic fish
Supporting services
Nutrient cycling
Decomposition
Composting
Earthworm activity
Microbial activity
Crop pollination
Cultural services
Recreation
Aesthetic enjoyment
Landscape appreciation
Fishing
Walking
Psychological wellbeing
Inspiration for art and culture
J. Pollination
Bees are important pollinators.
Other organisms also pollinate plants.
Pollinators support:
Crop production
Plant reproduction
Food security
Bee populations may be affected by:
Disease
Stress
Environmental pressures
Managed bee colonies may be transported to agricultural areas.
Losing pollinators could reduce crop production.
K. Biodiversity as a source of food
Humans use a relatively limited number of species as food.
Potential alternative food sources include:
Insects
Crayfish
Lobsters
Crabs
Other invertebrates
Mesopelagic fish
Insects can provide high protein.
Cultural attitudes influence food acceptance.
Mesopelagic fish are often processed into fishmeal.
Feeding fishmeal to farmed animals may involve energy losses.
L. Biodiversity and medicine
Biodiversity can provide useful biochemical compounds.
Traditional knowledge may help identify medicinal organisms.
Marine sponges produce unusual chemical compounds.
These compounds may have:
Anti-cancer potential
Antiviral potential
Other pharmaceutical applications
Researchers may:
Collect or study an organism.
Identify useful compounds.
Sequence its genome.
Identify the relevant gene.
Transfer the gene into bacteria.
Produce the compound through biotechnology.
M. Deep-water coral
Coral also occurs in deep, cold marine waters.
Cold-water coral can occur around Ireland.
It grows slowly.
It forms three-dimensional seafloor habitat.
It provides:
Shelter
Nursery areas
Juvenile fish habitat
Complex ecological structure
Industrial trawling can destroy coral structures.
Recovery may be very slow.
Habitat-forming organisms can have effects far beyond their own populations.
N. Ecology and ecosystems
Ecology studies relationships between organisms and their environment.
An ecosystem is a self-sustaining collection of organisms and their environments.
Ecosystems exist at different scales:
Pond
Lake
Island
River system
Earth
The biosphere is the largest global ecosystem.
A community is a group of organisms living in a particular place.
A habitat is the physical environment occupied by a community.
O. Abiotic and biotic factors
Abiotic factors
Sunlight
Temperature
Salinity
Sediment chemistry
Bedrock
Water movement
Nutrient availability
Physical conditions
Biotic factors
Plants
Animals
Fungi
Bacteria
Archaea
Microfauna
Meiofauna
Macrofauna
Megafauna
Predators
Parasites
Competitors
Decomposers
P. Biodiversity loss
Major causes discussed:
Habitat loss
Deforestation
Agricultural expansion
Palm-oil plantations
Dams blocking fish migration
Introduced species
Invasive species
Disease
Population growth
Pollution
Overconsumption
Resource exploitation
Q. Ecosystem change and shifting balance
Ecosystems are complex networks.
Loss of one species may sometimes have little immediate effect.
Functional redundancy may allow another species to perform a similar role.
Some species have unique or difficult-to-replace functions.
Ecosystems may pass tipping points.
Ecosystems are not permanently fixed or perfectly balanced.
Ecosystems are dynamic and constantly changing.
New ecological states may develop after biodiversity loss.
R. Conservation
Extinction is a natural evolutionary process.
Most species that have ever existed are extinct.
Humans have an unusually strong capacity to cause environmental change.
Conservation is therefore largely a human responsibility.
Reasons for conservation may include:
Ecosystem services
Human wellbeing
Moral considerations
Cultural value
Scientific value
Responsibility for human impacts
S. Keystone species
Keystone species have disproportionately large ecological effects.
Examples from the lecture include:
Sea otters
Apple snails
Pacific salmon
Beavers
Oysters
Possibly zebras, depending on the context
Keystone functions may include:
Controlling other populations
Creating habitat
Moving nutrients
Maintaining oxygen conditions
Altering water flow
Creating reefs or wetlands
T. Examples of keystone effects
Sea otters control sea urchins.
Sea urchins can damage kelp forests.
Kelp forests provide three-dimensional habitat.
Apple snails can contribute to bioturbation.
Pacific salmon transport marine nutrients inland.
Salmon nutrients support:
Aquatic insects
Riparian vegetation
Forests
Bears
Beavers construct dams and create wetlands.
Oysters build reefs from accumulated shells.
Oyster reefs provide habitat for fish, crabs, and other organisms.
3. Detailed multi-section fill-in-the-blank exercise
Section A — Definitions and levels of biodiversity
Biodiversity refers to the variety of ______ organisms on Earth or in a particular area.
The diversity of different species is called ______ diversity.
The variety of habitats and ecosystems is called ______ diversity.
Variation in genes and gene combinations within and between populations is called ______ diversity.
Lakes, rivers, forests, and savannas are examples of different ecological ______.
The potential role and resource use of an organism within its environment is associated with its ecological ______.
The niche actually occupied by an organism may be restricted by competition, predation, and other species ______.
Biodiversity includes not only species but also the interactions and relationships among ______.
A group of individuals of the same species living in a particular area may be described as a ______.
Genetic variation is often maintained within separate geographic ______.
Section B — Genetic diversity and salmon
The lecturer used brown trout from the River Liffey and River Boyne to illustrate differences between genetically separated ______.
Two populations may belong to the same species while having different genes and different combinations of ______.
Conservation should protect not only species but also their genetic ______.
Atlantic salmon selected for aquaculture may be bred for fast growth and delayed ______.
Farmed salmon may not survive as well as wild salmon because they were selected for controlled farming rather than natural ______.
The phrase “same species” does not mean that all populations are genetically ______.
Geographic isolation can reduce ______ flow between populations.
The ability of a population to respond to environmental change may depend partly on its genetic ______.
Section C — Global patterns of biodiversity
Biodiversity is not distributed ______ across the planet.
Large isolated landmasses may contain species that are ______ to those regions.
Terrestrial biodiversity is generally concentrated in the ______.
Repeated ice ages reduced biodiversity in many northern and southern ______.
Tropical climatic stability provides long periods for species to ______.
Speciation generally requires considerable amounts of ______.
Tropical rainforests contain complex three-dimensional habitat ______.
Biodiversity should not be confused with ______, which refers to the amount of biological material.
Marine biodiversity is often high around coastlines, islands, and ______ reefs.
Large areas of the open ocean may have low productivity because of limited ______ availability.
Section D — Microbial biodiversity and the history of life
Much of the world’s biological diversity is found among ______ organisms.
Bacteria and ______ are two major groups of microorganisms.
Cyanobacteria contributed to the increase of ______ in Earth’s atmosphere.
Oxygen was initially harmful to many organisms adapted to ______ conditions.
The lecturer described humans as walking ______ because different parts of the body support different microbial communities.
The microorganisms found on the foot may differ from those found in the ______.
Humans often underestimate microbial diversity because many microorganisms are ______.
The traditional division of life into animals, plants, and fungi does not fully represent the diversity of ______.
Section E — Ecosystem services
Ecosystem services are the benefits that humans obtain from ______.
Food, wood, and water are examples of ______ ecosystem services.
Climate regulation and pest control are examples of ______ ecosystem services.
Nutrient cycling and decomposition are often described as ______ ecosystem services.
Recreation, aesthetic enjoyment, and psychological wellbeing are examples of ______ ecosystem services.
Mesopelagic fish may contribute to the ocean’s biological ______ pump.
Ladybirds and parasitic wasps can provide biological ______ by reducing pest populations.
Earthworms and microorganisms contribute to ______ cycling.
Bees and other animals provide crop ______.
Natural environments may provide cultural benefits by reducing stress and improving human ______.
Section F — Food, medicine, and marine biodiversity
Insects and other invertebrates may provide alternative sources of ______.
Mesopelagic fish are often processed into fish ______ for use in animal feed.
Marine sponges produce unusual chemical ______ that may be useful in medicine.
Researchers may identify the gene responsible for a useful compound and transfer it into ______ to produce that compound.
Cold-water coral can occur in deep marine environments, including waters around ______.
Deep-water coral grows relatively ______ and may recover slowly after damage.
Coral creates a three-dimensional structure containing many ecological ______.
Deep-water coral can provide nursery habitat for juvenile ______.
Industrial ______ can damage or destroy deep-water coral habitats.
Section G — Ecology and ecosystem structure
Ecology is the study of relationships between organisms and their ______.
An ecosystem is a self-sustaining collection of organisms and their ______.
The largest ecosystem on Earth is the ______.
A group of organisms living together in a particular place is called a ______.
The physical location occupied by a community is its ______.
Sunlight, temperature, salinity, and sediment chemistry are ______ factors.
Plants, animals, fungi, bacteria, and archaea are ______ components of ecosystems.
Predation, parasitism, competition, and symbiosis are examples of species ______.
The movement of organisms or animals that disturbs sediment and changes its structure is called ______.
The size categories microfauna, meiofauna, macrofauna, and megafauna are partly ______ classifications.
Section H — Biodiversity loss, conservation, and keystone species
A major cause of biodiversity loss is the destruction or conversion of natural ______.
Deforestation for agriculture or plantations is an example of habitat ______.
Dams may cause biodiversity loss by preventing migratory fish from reaching their ______ grounds.
Species moved by humans into areas where they did not previously occur are called ______ species.
An introduced species that spreads and causes ecological damage may be described as ______.
The introduction of a predator to control a pest can have unintended ______ effects.
Pollution, population growth, and ______ are major pressures on biodiversity.
The loss of a species may sometimes have little immediate effect if another species can perform a similar ecological ______.
A species with a disproportionately large effect on ecosystem functioning is called a ______ species.
Sea otters help maintain kelp forests by consuming sea ______.
Pacific salmon transport marine ______ into freshwater and terrestrial ecosystems.
Beavers alter landscapes by constructing ______.
Oysters can create reef structures from accumulated ______.
Conservation is largely a human responsibility because humans have a strong capacity to alter the ______.
Ecosystems are dynamic and may move between different shifting states rather than remaining in one permanent state of ______.
Answers to the fill-in-the-blank exercise
Section A
living
species
ecological
genetic
habitats
niche
interactions
organisms
population
populations
Section B
populations
genes
variability
maturity
conditions
identical
gene
diversity
Section C
uniformly
unique
tropics
regions
evolve
time
complexity
biomass
coral
nutrient
Section D
microbial
archaea
oxygen
anaerobic
ecosystems
armpit
microscopic
microorganisms
Section E
ecosystems
provisioning
regulating
supporting
cultural
carbon
control
nutrient
pollination
wellbeing
Section F
protein
meal
compounds
bacteria
Ireland
slowly
niches
fish
trawling
Section G
environment
environments
biosphere
community
habitat
abiotic
biotic
interactions
bioturbation
arbitrary
Section H
habitats
loss
spawning
introduced
invasive
ecological
overconsumption
function
keystone
urchins
nutrients
dams
shells
environment
balance
4. Hard-level exam-style 40 MCQs
Questions
1. Which statement most accurately represents the lecturer’s definition of biodiversity?
A. The total number of animal species in a habitat B. The number of species present, excluding genetic differences C. The variety of living organisms, including species, ecosystems, and genetic variation D. The total biomass of organisms in an ecosystem
2. Why is it incorrect to equate biodiversity solely with species richness?
A. Species richness measures biomass rather than species number B. Biodiversity also includes ecological diversity, genetic diversity, and species interactions C. Species are not part of biodiversity D. Species richness only applies to microorganisms
3. An organism has the physiological capacity to use several food resources, but competition prevents it from using some of them. Which concept is most relevant?
A. The distinction between potential and realised niche B. The difference between biomass and productivity C. The distinction between abiotic and biotic factors D. The difference between provisioning and cultural services
4. Which situation is the clearest example of hyperparasitism?
A. A wolf consumes a deer B. A bird removes material from a crocodile’s mouth C. A wasp lays eggs inside an insect, and another parasite attacks the wasp larvae D. A plant competes with another plant for sunlight
5. Two brown trout populations live in separate river systems and have limited contact. Which statement is most consistent with the lecture?
A. They must be different species B. They cannot have genetic differences because they look similar C. They may belong to the same species while possessing different genetic characteristics D. They must have identical gene combinations because they are both brown trout
6. Why is the conservation of genetic diversity important?
A. It guarantees that every individual will survive B. It preserves variation that may help populations respond to environmental change C. It eliminates the need to conserve habitats D. It prevents all future mutations
7. Farmed Atlantic salmon may have reduced survival in the wild primarily because:
A. They belong to a completely unrelated species B. They have been selected for traits suited to aquaculture rather than natural environments C. They cannot reproduce under any circumstances D. They have no genetic variation whatsoever
8. Which example best demonstrates that “same species” does not necessarily mean “same ecological performance”?
A. Two organisms occupy the same habitat and eat the same food B. Farmed and wild salmon belong to the same species but have experienced different selection pressures C. Two individuals have exactly the same genes D. Two populations have identical environmental conditions
9. Which combination best explains the high biodiversity of many tropical regions?
A. Frequent glaciation and short evolutionary timescales B. Climatic stability, long evolutionary periods, and complex habitats C. Low productivity and limited habitat structure D. Complete absence of species interactions
10. Why can tropical rainforests support many specialised organisms?
A. They contain only one dominant habitat type B. Their three-dimensional structure creates numerous microhabitats and niches C. They have no competition or predation D. They contain less environmental variation than any other habitat
11. Which statement correctly distinguishes biodiversity from biomass?
A. Biodiversity measures the variety of life, whereas biomass measures the amount of biological material B. Biodiversity and biomass are identical measurements C. Biomass only applies to animals, whereas biodiversity only applies to plants D. High biomass always means high species diversity
12. Why are coastal and island-rich marine areas often highly biodiverse?
A. They contain no physical environmental variation B. They provide complex habitats with differences in depth, currents, substrate, and shelter C. They are always nutrient-free D. They exclude coral reefs and other habitat-forming organisms
13. Why might some large areas of the open ocean have relatively low biodiversity?
A. They contain too many different physical structures B. They may have low nutrient availability and limited habitat complexity C. They are always colder than polar waters D. They contain no microorganisms
14. Which statement best reflects the lecturer’s point about microbial biodiversity?
A. Microorganisms represent only a minor part of Earth’s biodiversity B. Most biodiversity is found among large visible animals C. Bacteria and archaea represent a major and highly diverse part of life on Earth D. Microorganisms do not influence ecosystems
15. What was the significance of cyanobacteria in the lecture?
A. They removed all oxygen from the atmosphere B. They helped oxygenate Earth’s atmosphere, changing conditions for later life C. They were the first animals to evolve D. They caused all modern species to become extinct
16. The description of humans as “walking ecosystems” mainly illustrates that:
A. Humans are independent of microorganisms B. different parts of the human body support different microbial communities C. only humans can form ecosystems D. microorganisms cannot live on animals
17. Which of the following is a provisioning ecosystem service?
A. Climate regulation B. Psychological restoration C. Production of food and wood D. Nutrient cycling by decomposers
18. Which process best illustrates a regulating ecosystem service?
A. The production of timber B. The use of a forest for recreation C. The reduction of pest populations by ladybirds or parasitic wasps D. The decomposition of dead leaves
19. The lecturer’s discussion of mesopelagic fish was mainly used to illustrate their possible role in:
A. terrestrial pollination B. transporting carbon and nutrients into deeper ocean waters C. creating freshwater wetlands D. preventing all marine fishing
20. Why could intensive fishing of mesopelagic fish be ecologically risky?
A. Their ecological role and total diversity may not be fully understood B. They are all invasive species C. They do not interact with any other organisms D. Their removal can only increase carbon storage
21. Which example is most directly associated with supporting ecosystem services?
A. A forest providing a scenic walking route B. Earthworms and microorganisms contributing to nutrient cycling C. Fish being harvested for food D. Wood being used for construction
22. Which statement about pollination is most accurate according to the lecture?
A. Honeybees are the only organisms capable of pollination B. Pollination has little importance for crop production C. Honeybees are important pollinators, although many other organisms also contribute D. Pollination is unrelated to biodiversity
23. Why are managed honeybee colonies transported between agricultural areas in some regions?
A. To remove all native pollinators B. To provide pollination services to crops C. To reduce plant reproduction D. To convert crops into wild species
24. Which statement best captures the lecture’s argument about alternative food sources?
A. Humans use every available species as food B. Insects and other invertebrates may provide nutritional alternatives, but cultural acceptance varies C. Mesopelagic fish have no nutritional value D. Food biodiversity is unrelated to ecosystem sustainability
25. What is the significance of marine sponges in biodiversity research?
A. They produce no biologically active chemicals B. They may produce unusual compounds with pharmaceutical potential C. They are only important as food for fish D. They are genetically identical to all plants
26. Which sequence best describes one modern biotechnology approach to discovering useful compounds?
A. Identify a compound, identify its gene, transfer the gene into bacteria, and produce the compound B. Destroy the source organism before examining it C. Remove all genetic material and rely only on visual identification D. Introduce the organism into every ecosystem on Earth
27. Why are cold-water corals ecologically important?
A. They grow rapidly and are easily replaced B. They create three-dimensional structures that provide habitat for other organisms C. They occur only in shallow tropical waters D. They prevent all fish from entering an area
28. What is a likely consequence of damaging slow-growing deep-water coral with industrial trawling?
A. Immediate restoration of coral habitat B. Loss of complex nursery and shelter habitat, potentially followed by slow recovery C. Increased coral growth due to disturbance D. Elimination of all abiotic factors from the seafloor
29. Which definition best matches ecology?
A. The study of only animal behaviour B. The study of relationships between organisms and their environment C. The study of only non-living environmental factors D. The classification of rocks and minerals
30. Which example is an abiotic component of an ecosystem?
A. A parasitic wasp B. A bacterial community C. Salinity D. A predator population
31. Which example is a biotic interaction?
A. Temperature change B. Sediment chemistry C. Predation between two species D. Salinity variation
32. Which statement correctly distinguishes a community from a habitat?
A. A community is the physical location, while a habitat is the organisms B. A community consists of organisms living together, while a habitat is the physical environment they occupy C. A community and a habitat are always identical concepts D. A habitat contains only abiotic factors and no organisms
33. Why might the loss of one species not immediately eliminate an ecosystem function?
A. Ecosystems contain no interactions B. Another species may perform a similar ecological role C. Species loss always increases biodiversity D. Ecosystem functions are unrelated to organisms
34. Which statement best reflects the lecturer’s view of ecosystem “balance”?
A. Ecosystems remain permanently unchanged unless humans interfere B. Ecosystems are dynamic and may shift between different states over time C. Ecosystems always return to exactly the same condition D. Ecosystems have no capacity to change naturally
35. Why can sea otters be considered a keystone species in kelp-forest systems?
A. They directly produce all kelp B. They control sea urchins, which can otherwise overconsume kelp C. They eliminate all predators from the ecosystem D. They increase sea urchin grazing pressure
36. Which example best demonstrates a keystone role through nutrient transport?
A. Pacific salmon bringing marine-derived nutrients into freshwater and terrestrial systems B. A bird consuming one insect C. A tree absorbing sunlight D. A rock changing temperature during the day
37. How can beavers influence biodiversity?
A. By preventing all water movement B. By building dams that alter water flow and create habitat structures C. By eliminating all wetland habitats D. By reducing landscape complexity in every circumstance
38. Which is the clearest example of habitat loss?
A. A species changing its feeding time B. A forest being cleared for a plantation C. A predator consuming prey D. A bird moving between two trees
39. Why can introduced species cause unexpected ecological damage?
A. Their effects are always limited to the intended target species B. They may lack natural controls, compete with native organisms, spread disease, or consume non-target species C. They are always genetically identical to native species D. They cannot survive outside their original range
40. Which statement best summarises the lecturer’s overall argument about conservation?
A. Conservation is unnecessary because extinction is natural B. Only large animals should be conserved C. Humans are part of nature but have unusual power to alter ecosystems, creating a responsibility to understand and manage their impacts D. Conservation should focus exclusively on economic benefits
MCQ answer key with explanations
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Question
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Answer
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Explanation
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| --- | --- | --- |
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1
|
C
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Biodiversity includes species, ecological, and genetic diversity.
|
|
2
|
B
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Biodiversity includes more than species number.
|
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3
|
A
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Competition can restrict an organism’s realised niche.
|
|
4
|
C
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Hyperparasitism occurs when a parasite is itself parasitised.
|
|
5
|
C
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Separate populations of the same species may differ genetically.
|
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6
|
B
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Genetic variation can improve a population’s ability to respond to change.
|
|
7
|
B
|
Farmed salmon are selected for aquaculture conditions.
|
|
8
|
B
|
Wild and farmed forms may have different ecological performance despite sharing a species name.
|
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9
|
B
|
Tropical stability and complexity support long-term diversification.
|
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10
|
B
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Three-dimensional forests create many microhabitats and niches.
|
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11
|
A
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Biodiversity concerns variety; biomass concerns biological mass.
|
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12
|
B
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Coastal areas provide physical and ecological complexity.
|
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13
|
B
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Some open-ocean areas have low nutrients and limited structure.
|
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14
|
C
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Microbes contain a major proportion of Earth’s biological diversity.
|
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15
|
B
|
Cyanobacteria contributed to atmospheric oxygenation.
|
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16
|
B
|
Different body regions support different microbial communities.
|
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17
|
C
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Food and wood are provisioning services.
|
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18
|
C
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Pest control is a regulating service.
|
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19
|
B
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Mesopelagic fish may help transport carbon and nutrients downward.
|
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20
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A
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Their abundance, diversity, and ecological role may be incompletely known.
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21
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B
|
Nutrient cycling supports ecosystem functioning.
|
|
22
|
C
|
Many organisms pollinate, but honeybees are important managed pollinators.
|
|
23
|
B
|
Managed colonies are moved to provide crop pollination.
|
|
24
|
B
|
Alternative foods may be nutritious, but acceptance varies culturally.
|
|
25
|
B
|
Sponges can produce unusual compounds with medical potential.
|
|
26
|
A
|
Genes for useful compounds may be transferred into bacteria for production.
|
|
27
|
B
|
Cold-water coral creates complex habitat structures.
|
|
28
|
B
|
Coral damage can remove nursery habitat and recovery may be slow.
|
|
29
|
B
|
Ecology studies organisms and their environments.
|
|
30
|
C
|
Salinity is non-living, so it is abiotic.
|
|
31
|
C
|
Predation is an interaction between living organisms.
|
|
32
|
B
|
A community is the organisms; a habitat is the environment they occupy.
|
|
33
|
B
|
Functional redundancy may allow another species to perform a similar role.
|
|
34
|
B
|
Ecosystems are dynamic and can shift between states.
|
|
35
|
B
|
Sea otters limit sea urchins and help protect kelp forests.
|
|
36
|
A
|
Salmon transfer marine nutrients inland.
|
|
37
|
B
|
Beaver dams change water flow and create or modify habitats.
|
|
38
|
B
|
Clearing forest for plantations removes or converts habitat.
|
|
39
|
B
|
Introduced species may spread, compete, transmit disease, or consume non-target organisms.
|
|
40
|
C
|
Humans are part of nature but have exceptional influence and responsibility.
|
Particularly difficult concepts to revise
Biodiversity is not just species richness.
Genetic diversity can exist between populations of the same species.
A species’ potential niche is not always the same as its realised niche.
Biodiversity and biomass are different concepts.
Microorganisms represent a major part of global biodiversity.
Ecosystem services are benefits humans receive; ecosystem functions can continue without humans.
Functional redundancy may reduce the immediate effect of species loss, but some species have difficult-to-replace roles.
Keystone species can influence ecosystems through predation, habitat creation, nutrient movement, or physical modification.
Habitat loss, introduced species, pollution, overconsumption, and population growth can interact rather than operate independently.
Conservation involves both ecological science and human ethical or philosophical decisions.
The main themes to prioritise for revision are:
The three levels of biodiversity: species, ecological, and genetic diversity
Ecological niches and the influence of competition and predation
The importance of conserving genetic variation within populations
Why biodiversity is concentrated in the tropics
The importance of microbial biodiversity
The four categories of ecosystem services
The role of biodiversity in pollination, pest control, food, medicine, and carbon cycling
The difference between abiotic and biotic ecosystem components
Functional redundancy, ecosystem change, and shifting ecological balance
Keystone species, including sea otters, salmon, beavers, oysters, and habitat-forming corals
Major causes of biodiversity loss: (HIPPO)
Habitat loss
Introduced and invasive species
Pollution
Population growth
Overconsumption
The scientific and philosophical reasons for conservation.