Coaching Centre
Ecosystems review
A summary of the whole Ecosystems chapter, key words, and a mixed test covering food webs, energy flow, human impacts, introduced species, microorganisms, natural events and sustainable farming.
Use this page to check the whole chapter. Read the summary, make sure you can explain every key word, then do the test without looking back.
Chapter summary
| Topic | What you need to know |
|---|---|
| 1A Ecosystems and the biosphere | Biosphere links atmosphere, hydrosphere and lithosphere. Ecosystem = community + abiotic factors + interactions. Biotic vs abiotic. Organism, population, community, ecosystem; habitat. Ecosystems give oxygen, clean water, pollination. |
| 1B Food chains and food webs | Producers (autotrophs) photosynthesise; consumers (heterotrophs): herbivores, carnivores, omnivores. Detritivores and decomposers recycle nutrients. Arrows point food → eater. Trophic levels. Removing a species affects predators, prey and competitors. |
| 1C Energy flow | About 10% of energy passes to the next level; the rest is lost as heat from respiration and in waste. Energy pyramids. Few top predators, short food chains. Energy flows, nutrients cycle. |
| 1D Habitat loss and pollution | Land clearing and urban sprawl remove producers; some species win (kangaroos), many lose. Erosion, compaction, overgrazing, overfishing. DDT and mercury: bioaccumulation and biomagnification harm top predators. |
| 1E Introduced species | Pests have no predators, outcompete natives, prey on defenceless animals. Biological control: cactus moth (success, well researched) vs cane toad (failure). Biodiversity makes ecosystems resistant to change. |
| 1F Microorganisms | Bacteria and archaea (prokaryotes), protists and microscopic fungi (eukaryotes). Cyanobacteria and stromatolites. Viruses aren't counted as living. Repeat trials and average for reliable results. |
| 1G Helpful microorganisms | Phytoplankton, nitrogen fixers; yoghurt, cheese, bread; rumen microbes digest cellulose; decomposers, compost, sewage, oil spills; your microbiome. |
| 1H Harmful microorganisms | Eutrophication: nutrients → algal bloom → light blocked → oxygen used up → fish die. Pathogens: bacteria, fungi, protists, viruses, prions. Food safety: below 5 °C, cook well. |
| 1I Managing natural events | Fire adaptations: bark, epicormic buds, lignotubers, fire-triggered seeds. Cool vs crown fires; fuel. Fire regimes, hazard reduction mosaics, cultural burning. Floods, drought, cyclones, earthquakes. |
| 1J Conservation and farming | Reasons to conserve. Ecological footprint. Green wedges and corridors. Dryland salinity. Soil organic carbon, no-till farming, organic fertilisers, dung beetles, selective breeding. |
Key words
abiotic · algal bloom · autotroph · bioaccumulation · biodiversity · biological control · biomagnification · biosphere · biotic · carnivore · community · consumer · cultural burning · decomposer · detritivore · ecological footprint · ecosystem · epicormic bud · eutrophication · extremophile · fire regime · food chain · food web · green corridor · habitat · herbivore · heterotroph · hyphae · introduced species · microbiome · microorganism · omnivore · pathogen · photosynthesis · population · producer · prokaryote · salinity · selective breeding · soil organic carbon · sustainable · trophic level
Test yourself
In the Antarctic food web below, what is the producer?
Phytoplankton photosynthesise; everything else depends on them.
Leopard seals eat penguins, which eat fish, which eat krill, which eat phytoplankton. The leopard seal in this chain is a
Phytoplankton (producer) → krill (1st) → fish (2nd) → penguin (3rd) → seal (4th).
A pesticide that doesn't break down is found in a lake. Which animal will contain the highest concentration?
Biomagnification concentrates the chemical at the top of the chain.
Which is an abiotic factor in a rock pool?
Temperature is a non-living condition.
Which group of microorganisms has no nucleus?
Bacteria (and archaea) are prokaryotes.
Why do fish die in an algal bloom?
Low dissolved oxygen suffocates them.
An ecosystem with high biodiversity is
With many species, some will cope with the change.
Which practice reduces dryland salinity?
Deep roots use the water and lower the water table.
Name the organisms in this Antarctic food web.
Is the microbe helping or harming?
Ecosystems are a balance between the living and the non-living conditions of the habitat. Feeding relationships are shown in food . photosynthesise, eat other organisms, and break down dead matter. Introducing species and clearing land for cities cause . Ecological research has improved the management of irregular natural and practices.
Someone asks you, "Why are ecosystems so important, and why should we care about protecting them?" Write a reply that uses ideas from across this chapter, with specific examples.
Ecosystems keep us alive. Plants and phytoplankton make the oxygen we breathe, roots and filter feeders like oysters help clean our water, and bees and other animals pollinate many of our crops. Decomposers such as fungi and bacteria recycle the nutrients in dead plants and animals so new plants can grow. Ecosystems also give us food, wool, timber and medicines; penicillin, for example, came from a mould.
Every species is connected through food webs, so damaging one part affects the rest. When cane toads were introduced without research, they poisoned native predators like quolls, and feral cats have helped drive many small mammals extinct. Ecosystems with high biodiversity cope better with diseases, droughts and fires, because some species will survive the change. Most of Australia's mammals and plants live nowhere else, so if we lose them here they're gone for ever.
The good news is that science helps us manage our impact. Biological control like the cactus moth, planned mosaic burning and cultural burning, no-till farming, dung beetles and replanting trees to fix salinity all let us use the land while protecting it. Finally, many people believe other species have a right to exist, and for Aboriginal peoples Country is part of who they are. For all these reasons, protecting ecosystems is protecting ourselves.