What is Biodiversity and Why Does it Matter? Revision Notes | GCSE OCR Foundation Biology

What this lesson covers

Explore the definition of biodiversity and understand how it provides stability to ecosystems by reducing species dependence on one another.

• Define biodiversity and explain its importance for ecosystem stability
• Describe how biodiversity reduces species dependence within ecosystems
• Explain the relationship between biodiversity and ecosystem resilience
• Evaluate the consequences of reduced biodiversity on ecosystem function

Key ideas to keep in view

Use this lesson to stay inside B6.1 Monitoring and maintaining the environment while connecting the detail back to the wider B6: Global challenges topic.

• B6: Global challenges
• B6.1 Monitoring and maintaining the environment
• GCSE OCR Foundation Biology

Lesson notes preview

Read the core explanations from What is Biodiversity and Why Does it Matter? before testing yourself from memory.

• Imagine a forest where only one type of tree grows. A single disease could wipe out the entire forest overnight. Now picture a forest with hundreds of different species - trees, shrubs, insects, birds, fungi. When disease strikes one species, the others keep the ecosystem running.
• This is biodiversity in action - nature's insurance policy. But what exactly is biodiversity, and why do ecosystems with more variety survive better than simple ones?
• The variety of all the different species of organisms on Earth, or within an ecosystem. This includes plants, animals, fungi, bacteria, and all other living things.
• Trap: Many students think biodiversity just means 'lots of animals'. Actually, it includes every living thing - from the tiniest bacteria in soil to the largest mammals, plus all the plants and fungi.
• Think of biodiversity like ingredients in a recipe. A simple sandwich needs bread and filling - just two ingredients. But a complex curry might need 20 different spices, vegetables, and proteins. The curry has higher 'ingredient diversity' than the sandwich.
• Ecosystems work the same way. A pond with just algae and fish has low biodiversity. A pond with algae, water plants, fish, frogs, insects, bacteria, and birds has high biodiversity.
• 3. The Stability Connection - Why More Species Means More Security
• Here's where biodiversity gets clever. High biodiversity creates ecosystem stability by reducing dependence between species. When species don't rely too heavily on just one other species, the whole system becomes more resilient.
• The ability of an ecosystem to maintain its structure and function over time, resisting changes and recovering from disturbances.
• Picture a food web like a safety net. In a simple ecosystem with few species, each strand of the net is thick and vital - if one breaks, the whole net fails. In a biodiverse ecosystem, there are many thin strands. If some break, others take the load.

Continue through the topic

Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.