Competition and Survival in Communities Revision Notes | GCSE AQA Higher Biology

1. The Battle for Survival

Picture a woodland in spring. Hundreds of bluebells are sprouting, but only some will flower. Squirrels are searching for nuts, but there aren't enough for everyone. This isn't random - it's competition, and it determines who lives, who dies, and who gets to reproduce.

Competition happens when organisms need the same resources but there isn't enough to go around. It's like a game of musical chairs - when the music stops, not everyone gets a seat.

Trap: Many students think competition only happens between different species. Actually, the fiercest competition is often between members of the same species because they need exactly the same resources.

2. What Plants Fight For

Plants might look peaceful, but they're in constant competition. Think about a forest floor where seedlings are trying to grow. They're all fighting for the same four things.

Light is the big prize. Plants need it for photosynthesis, but tall trees cast shadows. That's why you see plants growing towards windows - they're literally reaching for the light.

Space matters too. Roots need room to spread, and leaves need space to catch sunlight without being shaded by neighbours. Ever noticed how plants in a crowded garden bed grow tall and spindly? They're competing for space above ground.

Water and mineral ions from the soil complete the list. Root systems spread out like underground networks, each trying to absorb as much as possible before their neighbours get there.

3. What Animals Battle Over

Animals have different needs, so they compete for different resources. Watch any nature documentary and you'll see these three competitions playing out.

Food is obvious - there's only so much prey to go around. Lions compete with hyenas for zebra carcasses. Garden birds compete for seeds at your bird feeder.

Mates drive some of the most dramatic competitions. Male peacocks show off their tail feathers, stags lock antlers, and male robins sing to claim territory and attract females.

Territory is about securing a safe space with resources. A robin's territory might contain enough insects to feed its chicks, plus safe nesting sites. Defend the territory, secure the resources.

4. Winning the Competition - Adaptations

Some organisms are better competitors than others. They have adaptations - special features that give them an edge in the struggle for resources.

Think about how different plants solve the light competition problem. Some grow tall quickly to overtop their neighbours. Others, like ivy, climb up trees to reach the canopy. Some, like bluebells, flower early in spring before the trees get their leaves and block the light.

Animals have equally clever solutions. Cheetahs are built for speed to catch prey that other predators can't. Owls hunt at night when there's less competition. Woodpeckers have strong beaks to access insects that other birds can't reach.

Worked example: Analysing Adaptations for Competition

A cactus lives in a desert where water is scarce and many plants compete for it. Describe three adaptations that help it compete successfully.

1. Water is the limiting resource in deserts — This is what organisms are competing for
2. Widespread shallow root system to collect rainwater quickly — Adaptation 1: Better at gathering the resource
3. Thick, fleshy stem stores water for dry periods — Adaptation 2: Can survive when resource is unavailable
4. Spines instead of leaves reduce water loss by transpiration — Adaptation 3: Reduces waste of the precious resource

Answer: Widespread roots (collection), water storage in stem, spines reduce water loss

5. Competition in Action - Real Examples

Let's see how competition plays out in real habitats. Understanding these examples will help you tackle any exam question about competition.

In a pond, different species of water plants compete for light. Those floating on the surface (like water lilies) block light from reaching plants below. The underwater plants that survive are adapted to low light conditions.

On the African savanna, lions and hyenas compete for the same prey. Lions are stronger and hunt in coordinated groups, but hyenas have powerful jaws and hunt in larger packs. Both species have evolved different strategies to compete for the same food source.

In your garden, weeds compete with your vegetables for nutrients, water, and space. That's why gardeners remove weeds - to reduce competition and help their crops grow better.

6. Exam Success - Competition Questions

Competition questions appear regularly in GCSE exams. Here's how to tackle them and avoid the common traps that catch students out.

Command word alert: 'Suggest' questions about competition factors or adaptations can have multiple correct answers. Think about the organism's needs and environment.

Common mistake: Students often say animals compete for 'shelter' instead of being more specific. Better answers mention 'nesting sites', 'breeding territories', or 'safe places to raise young'.