Ecology
50 exam-style questions with answers for 4.7 Ecology in AQA GCSE Biology (spec 8461). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below. Not official AQA material.
All 50 questions and answers
Question 1 · Spec 4.7.1.1 · Communities
Define the term 'ecosystem'. [1 mark]
Answer:The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.Question 2 · Spec 4.7.1.1 · Communities
State three resources plants compete for. [3 marks]
Answer:Light and space (1); water (1); mineral ions from the soil (1).Question 3 · Spec 4.7.1.1 · Communities
State three resources animals compete for. [3 marks]
Answer:Food (1); mates (1); territory (1).Question 4 · Spec 4.7.1.1 · Interdependence
What is interdependence? [1 mark]
Answer:Species depend on each other for food, shelter, pollination and seed dispersal, so removing one can affect the whole community.Question 5 · Spec 4.7.1.1 · Communities
What is a stable community? [1 mark]
Answer:One where all the species and environmental factors are in balance, so population sizes remain fairly constant.Question 6 · Spec 4.7.1.2 · Abiotic factors
State four abiotic factors. [4 marks]
Answer:Any four from: light intensity (1); temperature (1); moisture levels (1); soil pH and mineral content (1); wind intensity and direction (1); carbon dioxide level for plants (1); oxygen level for aquatic animals (1).Question 7 · Spec 4.7.1.3 · Biotic factors
State three biotic factors. [3 marks]
Answer:Any three from: availability of food (1); new predators arriving (1); new pathogens (1); one species outcompeting another (1).Question 8 · Spec 4.7.1.4 · Adaptations
Name the three types of adaptation. [3 marks]
Answer:Structural (1); behavioural (1); functional (1).Question 9 · Spec 4.7.1.4 · Adaptations
What is an extremophile? [1 mark]
Answer:An organism that lives in extreme environments, such as high temperature, pressure or salt concentration.Question 10 · Spec 4.7.1.4 · Adaptations
Explain two adaptations of a polar bear. [2 marks]
Answer:Any two from: thick fur and fat for insulation (1); small ears to reduce surface area for heat loss (1); white fur for camouflage (1).Question 11 · Spec 4.7.2.1 · Food chains
What is a producer? [1 mark]
Answer:An organism, usually a green plant or alga, that makes glucose by photosynthesis; it starts a food chain.Question 12 · Spec 4.7.2.1 · Food chains
What happens to predator and prey populations? [2 marks]
Answer:They rise and fall in cycles (1); the predator population peaks after the prey population, as it depends on it for food (1).Question 13 · Spec 4.7.2.1 · Required practical 9
Describe how to estimate the population of daisies on a field using quadrats. [3 marks]
Answer:Place quadrats randomly, for example using random number coordinates (1); count the daisies in each and calculate the mean per quadrat (1); multiply by the number of quadrats that would fit in the field (1).Question 14 · Spec 4.7.2.1 · Required practical 9
A mean of 4 daisies per 0.25 m² quadrat is found. The field is 1200 m². Estimate the population. [2 marks]
Answer:4 ÷ 0.25 = 16 per m² (1); 16 × 1200 = 19 200 daisies (1).Question 15 · Spec 4.7.2.1 · Required practical 9
How is a transect used? [2 marks]
Answer:Quadrats are placed at regular intervals along a line (1); to see how the distribution of a species changes across a habitat (1).Question 16 · Spec 4.7.2.2 · Carbon cycle
State two processes that remove carbon dioxide from the atmosphere and two that return it. [2 marks]
Answer:Removed by photosynthesis (and dissolving in oceans) (1); returned by respiration and combustion (1).Question 17 · Spec 4.7.2.2 · Carbon cycle
Explain the role of decomposers in the carbon cycle. [2 marks]
Answer:Microorganisms break down dead plants and animals (1); their respiration releases carbon dioxide back into the air and mineral ions into the soil (1).Question 18 · Spec 4.7.2.2 · Water cycle
Describe the water cycle. [3 marks]
Answer:Water evaporates from the sea and land and transpires from plants (1); it condenses to form clouds (1); it falls as precipitation and runs back to the sea (1).Question 19 · Spec 4.7.2.3 · Decomposition
State three factors that affect the rate of decay. [3 marks]
Answer:Temperature (1); water availability (1); oxygen availability (1).Question 20 · Spec 4.7.2.3 · Decomposition
Why do gardeners make compost? [1 mark]
Answer:To use as a natural fertiliser.Question 21 · Spec 4.7.2.3 · Biogas
What is biogas and how is it made? [2 marks]
Answer:Mainly methane, used as a fuel (1); made by anaerobic decay of waste in a generator (1).Question 22 · Spec 4.7.2.3 · Required practical 10
Describe how to investigate the effect of temperature on the rate of decay of milk. [2 marks]
Answer:Add lipase to milk with phenolphthalein and sodium carbonate at different temperatures (1); time how long the pink colour takes to disappear as fatty acids lower the pH (1).Question 23 · Spec 4.7.2.4 · Environmental change · Higher only
State three environmental changes that affect species distribution. [3 marks]
Answer:Any three from: availability of water (1); temperature (1); atmospheric gases (1).Question 24 · Spec 4.7.2.4 · Environmental change · Higher only
Give an example of how a change in distribution can be caused by humans. [1 mark]
Answer:Climate change from burning fossil fuels causing species to move to cooler areas.Question 25 · Spec 4.7.3.1 · Biodiversity
Define biodiversity. [1 mark]
Answer:The variety of all the different species of organisms on Earth, or within an ecosystem.Question 26 · Spec 4.7.3.1 · Biodiversity
Why is high biodiversity important? [1 mark]
Answer:It makes ecosystems more stable, as species are less dependent on one another for food, shelter and maintenance of the environment.Question 27 · Spec 4.7.3.2 · Waste management
State three ways pollution affects ecosystems. [3 marks]
Answer:Pollution in water from sewage, fertiliser or toxic chemicals (1); in air from smoke and acidic gases (1); on land from landfill and toxic chemicals (1).Question 28 · Spec 4.7.3.2 · Waste management
Why is more waste produced today? [2 marks]
Answer:The human population is growing rapidly (1); and standards of living are rising, so more resources are used (1).Question 29 · Spec 4.7.3.3 · Land use
State two reasons why humans reduce the land available for other animals and plants. [2 marks]
Answer:Any two from: building (1); quarrying (1); farming (1); dumping waste (1).Question 30 · Spec 4.7.3.3 · Peat bogs
Why is destroying peat bogs harmful? [2 marks]
Answer:It reduces the area of this habitat and its biodiversity (1); peat decays or is burned, releasing carbon dioxide (1).Question 31 · Spec 4.7.3.4 · Deforestation
State three reasons for large-scale deforestation in tropical areas. [3 marks]
Answer:To provide land for cattle (1); for rice fields (1); to grow crops for biofuels (1).Question 32 · Spec 4.7.3.5 · Global warming
State three biological consequences of global warming. [3 marks]
Answer:Any three from: loss of habitat from rising sea levels (1); changes in species distribution (1); changes in migration patterns (1); reduced biodiversity (1).Question 33 · Spec 4.7.3.6 · Biodiversity
State three programmes to maintain biodiversity. [3 marks]
Answer:Any three from: breeding programmes for endangered species (1); protecting rare habitats (1); reintroducing field margins and hedgerows (1); reducing deforestation and carbon dioxide emissions (1); recycling instead of landfill (1).Question 34 · Spec 4.7.4.1 · Trophic levels
What are the trophic levels in a food chain? [2 marks]
Answer:Level 1: producers; level 2: primary consumers (herbivores) (1); levels 3 and 4: secondary and tertiary consumers (carnivores, with apex predators at the top) (1).Question 35 · Spec 4.7.4.1 · Decomposers
How do decomposers break down dead material? [1 mark]
Answer:They secrete enzymes into the environment and absorb the small soluble food molecules by diffusion.Question 36 · Spec 4.7.4.2 · Pyramids of biomass
What does a pyramid of biomass show? [1 mark]
Answer:The relative amount of biomass at each trophic level of a food chain.Question 37 · Spec 4.7.4.3 · Biomass transfer
State three reasons why biomass is lost between trophic levels. [3 marks]
Answer:Not all ingested material is absorbed; some is egested as faeces (1); some is lost as urea in urine (1); much is used in respiration, releasing carbon dioxide and water (1).Question 38 · Spec 4.7.4.3 · Biomass transfer
Calculate the efficiency of biomass transfer from 1000 kg to 100 kg. [2 marks]
Answer:100 ÷ 1000 (1); × 100 = 10% (1).Question 39 · Spec 4.7.4.3 · Biomass transfer
What percentage of light energy is typically used by producers? [1 mark]
Answer:About 1% of the light falling on them.Question 40 · Spec 4.7.5.1 · Food security
State three factors that affect food security. [3 marks]
Answer:Any three from: increasing birth rate (1); changing diets in developed countries (1); new pests and pathogens (1); environmental changes (1); cost of farming (1); conflicts (1).Question 41 · Spec 4.7.5.2 · Food production
How do farmers make food production more efficient? [2 marks]
Answer:Limiting animals' movement and keeping them warm (1); so less energy is transferred to the environment and more goes into biomass (1).Question 42 · Spec 4.7.5.2 · Food production
Give one ethical objection to intensive farming. [1 mark]
Answer:Animals are kept in cramped conditions that may cause suffering.Question 43 · Spec 4.7.5.3 · Sustainable fisheries
State two ways fish stocks can be maintained. [2 marks]
Answer:Any two from: fishing quotas (1); controlling net size, so young fish escape (1).Question 44 · Spec 4.7.5.4 · Biotechnology
What is mycoprotein? [2 marks]
Answer:A high-protein food made from the fungus Fusarium (1); grown in fermenters on glucose syrup (1).Question 45 · Spec 4.7.5.4 · Biotechnology
Why are GM crops developed? [1 mark]
Answer:To improve yields or provide more nutrients, e.g. golden rice with vitamin A.Question 46 · Spec 4.7.2.1 · Food chains
What is a primary consumer? [1 mark]
Answer:An animal that eats producers (a herbivore).Question 47 · Spec 4.7.1.4 · Adaptations
Explain one adaptation of cacti to dry environments. [1 mark]
Answer:Spines instead of leaves reduce water loss by transpiration.Question 48 · Spec 4.7.2.2 · Carbon cycle
Why does burning fossil fuels increase carbon dioxide levels? [1 mark]
Answer:Carbon stored for millions of years is released quickly as carbon dioxide by combustion.Question 49 · Spec 4.7.1.3 · Biotic factors
Explain how a new pathogen can affect a community. [2 marks]
Answer:It may kill many individuals of one species (1); which affects other species that depend on it for food (1).Question 50 · Spec 4.7.4.1 · Trophic levels
What is an apex predator? [1 mark]
Answer:A carnivore with no predators, at the top of a food chain.
More AQA GCSE Biology topics
- 4.1 Cell biology
- 4.2 Organisation
- 4.3 Infection and response
- 4.4 Bioenergetics
- 4.5 Homeostasis and response
- 4.6 Inheritance, variation and evolution
- 4.7 Ecology
Other Biology courses: AQA A-level Biology.