Living things don't survive alone — they depend on each other. This mini-lesson covers food chains and food webs, producers, consumers, predators and prey, competition, how toxic materials build up in a food chain, and why insect pollination keeps us fed.
Work through each screen, answer the questions as you go and collect ⭐ stars. Press Start when you're ready.
Every ecosystem starts with producers — usually green plants. They use light energy in photosynthesis to make their own food, so they trap the energy that everything else depends on.
Remember: a producer makes, a consumer takes. Nearly all food chains begin with a producer because it captures the Sun's energy first.
A food chain is a simple diagram of feeding relationships. The arrows show the direction energy flows — always from the organism being eaten to the organism doing the eating.
Common mistake: the arrow does not mean "eats". A points to B means A is eaten by B, so the energy travels along the arrow. Never draw the arrow pointing at the food!
A predator is an animal that hunts and eats other animals. Its prey is the animal that gets eaten.
Careful: "predator" is a role, not a fixed label. Whether an animal is predator or prey depends on which relationship you are looking at.
Tap an organism on the left, then tap its correct role on the right.
Most animals eat more than one thing, and most are eaten by more than one predator. When we join many food chains together we get a food web. It shows how everything in a habitat is connected.
Key idea: because everything is connected, removing one species affects many others — not just the ones it eats or is eaten by.
Organisms are interdependent — they rely on each other to survive. Because a food web is so connected, a change to one population sends ripples through many others.
Suppose disease wipes out most of the rabbits in the woodland web:
Big idea: you can't remove just one species. Take one away and the effects spread far beyond its direct neighbours.
Predator and prey numbers rise and fall in a repeating cycle. When prey are plentiful, predators have lots to eat and increase. More predators eat more prey, so prey numbers drop — then predators run short of food and drop too, letting prey recover.
Read it carefully: the prey peak comes first, then the predator peak follows. Predators can only build up after there is plenty of food.
Resources in a habitat are limited, so organisms compete for them. Whatever there isn't enough of, living things will compete for it.
Watch out: competition is strongest between organisms that need the same resources — for example two plants growing side by side both reaching for the same patch of light.
Some toxic materials (like certain pesticides or mercury) can't be broken down or removed by the body. When one organism eats another, the poison passes on and builds up. This is called bioaccumulation.
The concentration gets higher at each step up the food chain, so top predators end up with the most. This can poison them or stop them breeding.
Misconception: the amount of poison in the water may be tiny, but it still harms top predators most because it is concentrated as it passes up the chain.
Pollination is the transfer of pollen from the male part of a flower to the female part, so the plant can make seeds and fruit. Many plants rely on insects — especially bees — to carry that pollen for them.
As a bee visits flowers to collect nectar, pollen sticks to its body and rubs off onto the next flower — pollinating it. This lets crops set fruit and seeds.
Why it matters: a huge share of the crops we eat — apples, strawberries, beans and more — depend on insect pollinators. Fewer pollinators means less food for people, so protecting bees protects our food supply.
Tap the organisms in the correct order — start with the producer and follow the energy up to the top predator.
In a food web every organism is connected to several others. If one species is removed, the animals that ate it lose a food source and may fall in number, while the things it used to eat may increase. These changes then affect their predators and prey, so the effect spreads through many populations — not just the ones directly linked to the missing species.
Producers make food from light; consumers eat other organisms.
Food-chain arrows show the direction energy flows: from food to feeder.
Predators hunt prey; their numbers cycle, with prey peaking first.
Interdependence: removing one species affects many others.
Competition happens when a resource (food, water, light, space) is limited.
Bioaccumulation: toxins build up, highest in the top predator.
Insect pollination lets crops make fruit and seeds — vital for our food.
You've covered the whole KS3 "Interactions and interdependencies" topic. Press Finish to see your score.
You've worked through Interactions & Interdependencies for KS3 Science. 🎉
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