Food Chains, Food Webs & Human Impact on Ecosystems: MYP Biology (Amazon Rainforest Case Study)
An ecosystem is a web of living things and their surroundings, all linked by who eats whom. Food chains and food webs are the diagrams biologists use to show those links — and once you can read them, you can predict what happens when something in the ecosystem changes. That skill is exactly what MYP Biology assessments test, usually through an unfamiliar ecosystem like the Amazon rainforest.
Try it yourself: identify consumers, classify organisms in a food web, work out how removing a species affects the rest, and analyse deforestation data. It builds an assessment report at the end.
Reading a food chain
A food chain shows one path of energy through an ecosystem, starting with a producer (a plant or other organism that makes its own food using light energy) and moving through consumers. A primary consumer eats the producer, a secondary consumer eats the primary consumer, and so on. The arrows point in the direction energy flows — from the organism being eaten to the organism doing the eating — which is the opposite of what many students first assume.
Why energy runs out
Only a fraction of the energy at one level reaches the next; the rest is used for life processes like movement and keeping warm, or lost as heat and in waste. As a rough guide, about a tenth is passed on, which is why food chains are short and why there are far fewer top predators than plants. When an exam asks "why are there fewer organisms at higher levels?", the answer is energy loss at each transfer.
Food webs: many chains woven together
Real animals eat more than one thing, so ecosystems are better shown as food webs. A web explains why removing one species rarely has a single, simple effect: if a predator disappears, its prey may increase, and then the plants that prey depends on decrease. To answer "predict the effect" questions, trace the arrows both up and down from the changed species and describe each consequence in order.
Abiotic factors and human impact
Living things also depend on non-living (abiotic) factors such as light, temperature, water and soil. Deforestation changes several at once: it removes the producers that support the whole web, destroys habitat, exposes soil to erosion, and can alter local rainfall. Because the food web is so interconnected, losing forest cover affects species that never lived in the trees themselves.
Connecting local change to global effects
Higher-band answers link a local change to a wider one: forests store carbon, so clearing them releases carbon dioxide and contributes to climate change, which in turn affects ecosystems far away. This is the kind of impact reasoning MYP rewards under Criterion D.
Frequently asked questions
They point from the organism being eaten to the organism that eats it, showing the direction energy flows.
Energy is lost at every step of a food chain (as heat and in life processes), so less energy is available at each higher level to support organisms.
The effects spread: its predators may lose food, its prey may increase, and the plants that prey feed on may decline. Trace each link to predict the outcome.