The Earth's Four Spheres
Which two spheres are most directly involved when plants take in carbon dioxide and release oxygen during photosynthesis?
Biosphere and atmosphere
What does “biodiversity” mean?
The variety of living things in an environment.
Name one natural event that changes the biosphere.
Flood, drought, bushfire, earthquake.
What is climate change?
A long-term change in the Earth’s temperature and weather patterns.
In what way can deforestation make natural hazards like flooding or landslides worse?
Removing trees reduces root systems that hold soil together and absorb water, leading to soil erosion and increased runoff during heavy rain.
When a volcanic eruption releases ash and gases into the air, which two spheres are interacting?
Geosphere and atmosphere
Do tropical rainforests have high or low biodiversity? Why?
High, because of warm, wet conditions all year.
Name one human activity that changes the biosphere.
Deforestation, farming, mining, urbanisation.
What type of human land use is a major source of methane emissions, a powerful greenhouse gas?
Livestock farming (especially cattle) produces large amounts of methane.
What is one sustainable way humans can use land?
Crop rotation, conservation farming, national parks.
Heavy rainfall causes soil erosion and nutrients to wash into rivers. Which three spheres are involved in this process?
Atmosphere, hydrosphere, and lithosphere
Why do deserts have less biodiversity than rainforests?
Lack of rainfall and extreme heat make survival difficult.
How can a bushfire be both a natural and a human impact?
It can start naturally from lightning or be caused by humans (accidents or land clearing), and it impacts ecosystems either way.
How does urbanisation (the growth of cities) affect local climates?
Urban areas create “heat islands” — they trap heat due to concrete, asphalt, and fewer trees, raising local temperatures.
Why is sustainable land management essential for protecting the geosphere and biodiversity?
It prevents soil erosion, deforestation, and habitat loss, maintaining healthy ecosystems and fertile land for future use.
Climate change leads to warmer oceans, coral bleaching, and loss of marine species. Explain how this demonstrates the connection between the four spheres
Lithosphere, hydrosphere, biosphere, atmosphere
Explain how altitude influence biodiversity
At low altitudes, conditions are warmer, wetter, and more stable — so biodiversity is high.
At high altitudes, it’s colder and harsher — so biodiversity is lower.
The 2019–2020 Australian bushfires destroyed millions of hectares of forest. Which spheres were affected?
Biosphere, Lithosphere, Hydrosphere, Atmosphere.
Explain how human land use can both worsen and help fight climate change.
Land use like deforestation, farming, and urban development releases greenhouse gases and reduces natural carbon storage. However, reforestation, sustainable farming, and renewable energy projects can absorb carbon and reduce emissions, helping combat climate change
What happens when invasive species outcompete native species?
The native species can decline or become extinct.
A drought affects plants and animals. Which spheres are involved and how?
Hydrosphere (less water), Biosphere (living things suffer)
Why is northern Australia more biodiverse than central Australia?
Northern areas are wetter and warmer; central areas are dry desert.
How can land use for farming or cities lead to soil degradation and loss of biodiversity?
Clearing land removes vegetation and tree roots, leading to erosion, poor soil health, and loss of habitats for plants and animals.
Explain how rising global temperatures affect biodiversity.
Warmer climates change habitats — species may migrate, die out, or lose food sources.
How can individuals reduce their impact on the biosphere?
Recycling, planting trees, using less energy, reducing waste.