Water Cycle

    OCR
    GCSE

    The water cycle describes the continuous movement of water through the biosphere, driven by solar energy and gravity. Key processes include evaporation from oceans and transpiration from plants, which return water vapor to the atmosphere for condensation and subsequent precipitation. Candidates must analyze how water moves through abiotic and biotic components, including surface runoff, infiltration, and groundwater flow. Understanding this cycle is fundamental to explaining nutrient transport, the maintenance of habitats, and the dependence of all living organisms on water for metabolic reactions.

    0
    Objectives
    3
    Exam Tips
    4
    Pitfalls
    4
    Key Terms
    5
    Mark Points

    What You Need to Demonstrate

    Key skills and knowledge for this topic

    • Award 1 mark for stating that energy from the Sun causes water to evaporate from oceans and lakes
    • Credit responses that identify transpiration as the release of water vapour from plants/leaves
    • Award 1 mark for describing condensation as the cooling of water vapour to form clouds (liquid droplets)
    • Candidates must link precipitation to surface run-off or percolation/infiltration into the soil
    • Award 1 mark for including respiration as a biological process that returns water to the atmosphere

    Example Examiner Feedback

    Real feedback patterns examiners use when marking

    • "You have correctly identified the physical processes; now ensure you include the biological processes like transpiration"
    • "Be careful with states of matter — remember that clouds are liquid droplets, not gas"
    • "Good use of terminology. To improve, explain how deforestation would specifically impact the transpiration stage of this cycle"
    • "You mentioned water returning to the sea; try to distinguish between surface run-off and groundwater flow (percolation)"

    Marking Points

    Key points examiners look for in your answers

    • Award 1 mark for stating that energy from the Sun causes water to evaporate from oceans and lakes
    • Credit responses that identify transpiration as the release of water vapour from plants/leaves
    • Award 1 mark for describing condensation as the cooling of water vapour to form clouds (liquid droplets)
    • Candidates must link precipitation to surface run-off or percolation/infiltration into the soil
    • Award 1 mark for including respiration as a biological process that returns water to the atmosphere

    Examiner Tips

    Expert advice for maximising your marks

    • 💡Always specify the state change (e.g., 'liquid to gas') when defining evaporation or condensation to secure AO1 marks
    • 💡When asked about the role of trees, explicitly use the term 'transpiration' rather than just 'water loss'
    • 💡In 'Suggest' questions regarding deforestation, link the removal of trees to reduced transpiration and subsequent changes in local rainfall patterns

    Common Mistakes

    Pitfalls to avoid in your exam answers

    • Identifying clouds as 'water vapour' (gas) rather than condensed liquid water droplets
    • Failing to distinguish between evaporation (physical) and transpiration (biological) when describing water loss from land
    • Omitting the role of living organisms (respiration/excretion) in returning water to the cycle
    • Confusing 'infiltration' or 'percolation' with simple surface run-off

    Key Terminology

    Essential terms to know

    Physical phase changes (Evaporation, Condensation, Precipitation)
    Biological contributions (Transpiration, Respiration, Decomposition)
    Percolation, infiltration, and surface runoff
    Importance of water as a universal solvent and reactant

    Likely Command Words

    How questions on this topic are typically asked

    Describe
    Explain
    Label
    Suggest
    Complete

    Practical Links

    Related required practicals

    • •{"code":"PAG 6","title":"Measurement of the rate of transpiration (Potometer)","relevance":"Demonstrates the biological contribution to the water cycle"}

    Ready to test yourself?

    Practice questions tailored to this topic