Life and ecosystems
An ecosystem is made up of living organisms and the physical environment in which they interact. Plants, animals, fungi and microorganisms can be connected through food webs, competition, cooperation and the movement of nutrients. A change to one part of an ecosystem can affect many others.
Adaptation and survival
Living organisms have characteristics that help them survive and reproduce in particular environments. Adaptations can involve body structures, behaviour or biological processes. Over generations, inherited variation and natural selection can contribute to populations becoming better suited to their surroundings.
Habitats and biodiversity
A habitat provides the conditions an organism needs to live. Forests, grasslands, wetlands, oceans and deserts support different communities of life. Biodiversity describes the variety of living organisms and is important because ecosystems depend on many interacting species and processes.
Learning from the natural world
Nature is easier to understand when individual facts are connected to relationships. Instead of only memorising a species name, consider its habitat, food, behaviour and role in its ecosystem. Quiz explanations can provide a useful starting point for those connections.
Energy flows, but nutrients are recycled
Many food webs begin with plants or algae that capture energy from sunlight through photosynthesis. Herbivores gain energy when they eat plants, and predators can gain energy by eating other animals. At each transfer, organisms use much of the available energy for life processes and release some as heat, so less is available to the next level. Fungi, bacteria and other decomposers break down dead material and waste, returning nutrients to soil and water where they can be used again. This is an important difference: nutrients circulate through ecosystems, but energy is not recycled in the same way.
A practical example: a change in a food web
If a predator becomes less common, the number of its prey may rise. More prey can then put greater pressure on plants or smaller animals, affecting other parts of the ecosystem. The real outcome depends on the species and conditions involved, so ecologists study food webs and collect observations rather than assuming every ecosystem responds in the same way. Consider a simple woodland with plants, rabbits and foxes. A fall in fox numbers might be followed by more rabbits, but disease, food supply, weather and other predators can also affect the outcome. To investigate, researchers could survey the same area repeatedly, track several species and compare observations across seasons rather than treating one count as proof of cause and effect.
Further reading
These links provide further reading from established organisations, including subject explanations, source material and reference databases. They are not citations for every sentence in this guide.