AQA Biology 4.7.1.1 · Combined and Triple
Ecosystems
Four words that fit inside each other, and a woodland where taking one species out moves all the others.
Combined Science · Higher tier
Start here
The bees vanish.
One summer, every bee in a park disappears.
If you had to guess, would the park’s flowers be fine, or would they suffer?
Levels of organisation
Organism, population, community, ecosystem.
Each word holds the one before it. Step through a wood.
Organism: one individual living thing. One robin. Predict: all the robins in the wood are a…
A habitat is the place where an organism lives: the woodland floor, the canopy, a pond.
People make artificial ecosystems too: farmland growing a single crop has far fewer species than a natural wood, because one crop dominates and most other species are removed.
What does an ecosystem include that a community does not?
Pick one.
Interdependence
Take one species out.
Within a community each species depends on other species for food, shelter, pollination and seed dispersal. Remove one and follow the knock-on. Arrows point from the food to the eater; the dashed arrow is pollination.
Leaf litter feeds earthworms, which feed shrews. Grass, shrubs and flowering plants feed deer, which feed wolves. Flowering plants feed bees with nectar; bees pollinate the flowering plants.
A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant. Which of these describes a stable community?
Pick one.
Plants in a community often compete with each other for light and space, and for water and mineral ions from the soil; animals often compete with each other for food, mates and territory. Competition is taught in full in Population and competition.
From data
Explain the change.
You should be able to explain how a change to a community affects other populations, using data as evidence.
Information · made-up data for practice
Wolves were removed from a wood in year 0. Deer counted: year 0, 40; year 2, 95; year 4, 160. Shrub cover: year 0, 100%; year 2, 70%; year 4, 35%. Ground-nesting birds: year 0, 30 pairs; year 4, 12 pairs.
Why did the number of ground-nesting birds fall?
Pick one.
Think again · community or ecosystem?
“A community and an ecosystem are the same thing.”
Your call
ChooseA wood’s oaks, deer, fungi and bacteria, with its soil, rainfall and light. Which word covers all of that?
Sort
Which level?
Place each one.
Tap a card, then tap the box it belongs in. Tap a placed card to take it back.
Command words in this lesson
- Define
- Population, community, ecosystem, habitat.
- Explain
- How removing one species changes others, using data.
- Describe
- What a stable community is.
- Suggest
- What organisms in a given habitat compete for (Population and competition).
Key fact
An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment. Species depend on each other for food, shelter, pollination and seed dispersal, so removing one changes the rest.
Key note · AQA 4.7.1.1
Ecosystems
- Organism, then population (all of one species in an area), then community (all the populations of different species), then ecosystem (the community interacting with the non-living, abiotic parts of its environment). A habitat is the place an organism lives.
- Within a community each species depends on others for food, shelter, pollination and seed dispersal. This interdependence means removing one species changes the others.
- A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.
- Explain a change using the data: say which number rose or fell, then link it to the next.
- Artificial ecosystems such as single-crop farmland have lower biodiversity than natural ones.
Photograph this card. Tomorrow, cover it and say each line first.
Previous and next
Connects to
Ask MrBadmus
Still mixing up community and ecosystem?
The wood, its species and all counts are made up for practice.