Ecosystems and Biodiversity

$\text{Producer} \rightarrow \text{Primary consumer} \rightarrow \text{Secondary consumer} \rightarrow \text{Tertiary consumer}$

• Producers: photosynthesise (plants, algae)
• Consumers: eat other organisms
• Decomposers: break down dead matter (bacteria, fungi); recycle nutrients

Extremophiles: organisms adapted to extreme environments (hot springs, high salt).

Quadrats

• Square frames placed randomly
• Count organisms inside
• Calculate population: $\text{population} = \frac{\text{number in sample}}{\text{area of sample}} \times \text{total area}$

Transects

• Line across a habitat; place quadrats at regular intervals
• Shows how species distribution changes across an area

Capture-Recapture (for animals)

$\text{Population} = \frac{\text{number in 1st capture} \times \text{number in 2nd capture}}{\text{number recaptured (marked)}}$

The variety of all living organisms in an ecosystem.

High biodiversity = more stable ecosystem.

Threats to Biodiversity

• Habitat destruction (deforestation, urbanisation)
• Pollution (water, air, land)
• Climate change
• Overexploitation (overfishing, hunting)
• Invasive species

Conservation

• Nature reserves and national parks
• Breeding programmes (captive breeding)
• Seed banks
• Legislation (laws protecting species)
• Habitat restoration

• Ecosystem: community + abiotic environment
• Food chains: producer → consumer → decomposer
• Adaptations: structural, behavioural, functional
• Sampling: quadrats, transects, capture-recapture
• Biodiversity threatened by human activities; conservation essential