Ecosystems Under Stress | AQA A-Level Geography (7037)

Ecosystems Under Stress

357 questions
26 subtopics
Component 1 Section C: Hazards or Ecosystems under stress
Component 1

Ecosystems from trophic structure and nutrient cycling up to the global biomes, then the pressures on rainforest, savanna, coral reef and local habitat, and what sustainable management involves.

One of two Section C options in Component 1.

Sample questions from Ecosystems Under Stress

Answer each one closed book first, then open the answer.

Biodiversity Levels and Causes of Decline

What is ecosystem diversity?

Show the answer
The variety of different habitats, biological communities and ecological processes within a region
Ecosystem Inputs, Outputs, Stores and Transfers

How does water leave an ecosystem?

Show the answer
Through evapotranspiration from soil and vegetation surfaces.
Environmental Controls and Ecosystem Feedback

How do temperature changes from climate change affect ecosystems?

Show the answer
They alter growing conditions, metabolic rates, and can cause heat stress in organisms.
Savanna Climate, Soils and Adaptations

What problems does the laterite duricrust cause in savanna soils?

Show the answer
It can impede root penetration and drainage.
Succession and Climatic Climax

Where do mosses establish during a lithosere and why?

Show the answer
Mosses establish in crevices where debris accumulates, providing a foothold for colonisation.
Coral Reef Conditions, Services and Stresses

Why can coral reefs not tolerate significant freshwater influx?

Show the answer
Corals require stable salinity levels within a narrow range (32–42 parts per thousand) and cannot tolerate the dilution caused by freshwater.
Crown-of-Thorns Starfish and Reef Tourism

Explain how nutrient pollution exacerbates crown-of-thorns starfish outbreaks.

Show the answer
Nutrient-enriched waters provide ideal conditions for crown-of-thorns larvae to thrive, leading to larger adult populations.
Agriculture, Urbanisation and Invasive Species

How does urban development cause habitat fragmentation?

Show the answer
Built areas divide continuous habitats into smaller, isolated patches, restricting species movement and gene flow between populations.

The 26 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Biodiversity Levels and Causes of Decline	Recall questions on genetic, species and ecosystem diversity, species richness and evenness, local trends, extinction rates and threatened hotspots, and on overexploitation, invasive species, pollution and climate change as causes of decline, phenological mismatch and metrics of loss.	16
Biodiversity Loss and Ecosystem Services	Recall questions on resilience, trophic cascades, the shrinking genetic pool and what ecosystem services provide.	18
Ecosystem Structure, Trophic Levels and Food Webs	Recall questions on what an ecosystem is, its biotic and abiotic components and the flow of energy, on producers, primary, secondary and tertiary consumers and decomposers, and on food chains, food webs and energy transfer between trophic levels.	12
Ecosystem Inputs, Outputs, Stores and Transfers	Recall questions on solar energy, precipitation, weathered nutrients and atmospheric gases as ecosystem inputs, heat, water and nutrient losses as outputs, biomass, litter, soil organic matter and soil nutrients as stores, and photosynthesis, respiration, decomposition, root uptake and consumption as transfers.	16
Biomass, Net Primary Production and Succession	Recall questions on biomass, net primary production and its formula, and on succession, seral stages, pioneer species, climatic climax and sub-climax.	9
Nutrient Cycling, Climate and Soil	Recall questions on mineral nutrient cycling between soil, biomass and litter and why its rate varies, on how climate, vegetation and soil influence one another through nutrients, water retention, drainage and rooting depth, and on the effects of aspect, altitude and slope.	17
Environmental Controls and Ecosystem Feedback	Recall questions on why climate, vegetation, soil and relief are interconnected and on positive and negative feedback loops.	14
Biomes and the Tropical Rainforest Environment	Recall questions on biomes, the seven major terrestrial biomes and why latitude governs their distribution, and on the tropical rainforest's location, rainfall, temperatures, nutrient-poor soils, nutrient stores and cycling, and soil moisture budget.	14
Rainforest Stratification and Adaptations	Recall questions on the emergent, canopy, understorey and shrub layers and the forest floor of a tropical rainforest, and on adaptations including buttress roots, drip tips, lianas, epiphytes and the adaptations of rainforest fauna.	13
Savanna Climate, Soils and Adaptations	Recall questions on savanna latitudes, wet and dry seasons and the ITCZ, rainfall, temperatures, laterite soils and the soil moisture budget, grasses, thick bark, waxy leaves, tap roots, baobabs and deciduous trees as adaptations, fauna and large herbivore populations, and how savanna differs from rainforest in the amount and seasonality of rainfall.	20
Human Impacts on the Tropical Rainforest	Recall questions on how deforestation and logging affect rainforest soils, nutrient cycling and biodiversity, habitat fragmentation, slash and burn, cattle ranching and mining, population and economic pressures, agricultural extension and intensification, threatened ecosystem services and approaches to sustainability.	13
Human Impacts on the Savanna	Recall questions on overgrazing and desertification, why frequent burning favours grasses over trees, poaching, population growth and economic development, agricultural extension and irrigation, the causes of biodiversity loss, and what sustainable land management in savannas requires.	11
Succession and Climatic Climax	Recall questions on what succession is, why a climatic climax community persists and what a lithosere describes.	17
Temperate Deciduous Woodland	Recall questions on temperate deciduous woodland as the climatic climax of the British Isles, why its trees shed leaves, its canopy, sub-canopy, shrub, field and ground layers, seasonal light and spring-flowering ground flora, and its brown earth soils.	11
Plagioclimax and Heather Moorland	Recall questions on what a plagioclimax is, a British example, and how controlled burning holds moorland short of woodland.	8
Coral Reef Conditions, Services and Stresses	Recall questions on the latitudes, temperature, clear shallow water, zooxanthellae and salinity coral reefs need, their structure and ecology, their coastal protection, economic and nursery services, and stresses from bleaching, ocean acidification, salinity change, algal blooms and drainage basin schemes.	20
Human Pressures and Coral Reef Management	Recall questions on onshore development, desalination discharges, agricultural runoff, industrial contamination and plastic, damage from boats, divers, tourism sewage and construction, overfishing and destructive fishing, the prospects for reefs and the Great Barrier Reef, and protected areas, regulation, pollution reduction and restoration.	18
The Great Barrier Reef: Extent and Bleaching	Recall questions on where the reef lies, how far it stretches and when mass bleaching occurred.	8
Crown-of-Thorns Starfish and Reef Tourism	Recall questions on why starfish outbreaks harm the reef, how nutrient pollution worsens them and why tourism needs managing.	8
Local Ecosystems: Heathland, Parkland, Ponds and Dunes	Recall questions on local ecosystems, heathland soils, shrubs and burning, managed parkland with its ground layer, old trees, woodland edges and maintenance, pond zonation and marginal and emergent plants, and the succession from embryo to yellow, grey and fixed dunes.	17
Adaptations to Dry Environments	Recall questions on reduced and rolled leaves, waxy cuticles and sunken stomata, and on why animals become nocturnal.	13
Agriculture, Urbanisation and Invasive Species	Recall questions on habitat loss, monoculture, nutrient runoff and soil compaction from agriculture, on habitat fragmentation, impermeable surfaces and pollution from urban development, and on species introductions and how invasive species exclude natives, disrupt food webs, transmit disease and modify habitats.	13
Ecological Change and Conservation Strategies	Recall questions on how ecological change causes biodiversity loss and degrades ecosystem services, nutrient cycles and resilience, and on conservation through habitat restoration, wildlife corridors, invasive species management, stakeholder consultation, funding, monitoring, adaptive management, SSSIs and agri-environment schemes.	13
Sustainability and Stakeholder Conflict	Recall questions on what sustainable development means locally and on the conflicting interests and funding limits it meets.	11
Studying Local Ecosystems and Ecological Change	Recall questions on studying a distinctive local ecosystem, its characteristics, ecological responses, local factors, properties, human impacts, conservation and sustainable development, and on a case study of a region experiencing ecological change and the community responses it illustrates.	16
Ecological change in Borneo	Ecological change in Borneo as a regional case study, covering the loss of rainforest and peat swamp forest to logging, oil palm and fire, the effects on orangutans and the carbon cycle, and responses from certification to conservation.	11

Ecosystems Under Stress is 357 of the 3,320 questions in the guide.Get the guide, £7

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.