Science Masters – Specified Practical Activities (Experiments 1–3)

Each card shows the core experiment structure (aim, variables, result, conclusion) on the left and space for a simple diagram on the right.

Experiment 1 – Cation Exchange Capacity of Soils (5.1a)

Aim: To compare the cation exchange capacity (CEC) of two different soil types.
Hypothesis: Clay / high organic matter soil will have a higher CEC than sandy soil.
Independent variable: Soil type (e.g. sandy vs clay / loam).
Dependent variable: Amount of cation (e.g. Ca²⁺) adsorbed / released from the soil.
Control variables: Mass of soil, volume and concentration of CaCl₂ / HCl used, contact time, temperature.
Result (short): Clay / high organic matter soil shows greater cation exchange than sandy soil.
Conclusion: Soils with more clay and organic matter have higher CEC and better nutrient-holding capacity.

Simple diagram idea:

  • Two test tubes for each soil type.
  • Labels for CaCl₂ / HCl solutions.
  • Arrow showing comparison of cation exchange.

You can replace this box with a sketch or image later.

Experiment 2 – Estimating Earthworm Population in Soil (17.1)

Aim: To estimate earthworm population per m² as an indicator of soil biological activity.
Hypothesis: Well-managed grassland will have more earthworms than poorly managed soil.
Independent variable: Field / soil management type sampled (e.g. permanent pasture vs poached paddock).
Dependent variable: Number of earthworms counted per sampling pit / per m².
Control variables: Size and depth of pit (e.g. 20 cm × 20 cm × 20 cm), time of year, sampling method, counting time.
Result (short): Better-managed grassland shows higher earthworm counts than compacted / poorly managed soil.
Conclusion: Earthworm numbers can be used as a simple indicator of soil structure and biological health.

Simple diagram idea:

  • Quadrat outline on grassland.
  • Marked pit (20 cm × 20 cm × 20 cm).
  • Tray or sheet where earthworms are collected and counted.

Replace with your own earthworm pit sketch if you prefer.

Experiment 3 – Determining Soil Organic Matter by Loss on Ignition (19.1)

Aim: To determine the percentage of organic matter in a soil sample.
Hypothesis: Soils with more organic matter will lose more mass when heated strongly.
Independent variable: Soil sample tested (e.g. peat, loam, sandy soil).
Dependent variable: Mass of soil lost on ignition (as a percentage of original dry mass).
Control variables: Mass of soil in crucible, drying time and temperature, ignition time and temperature.
Result (short): Peaty / high-organic soils show greater percentage mass loss than mineral soils.
Conclusion: % organic matter = (mass lost ÷ original dry mass) × 100; higher values mean more humus.

Simple diagram idea:

  • Soil in a labelled crucible on a tripod and gauze.
  • Bunsen burner underneath.
  • Balance for weighing crucible + soil before and after ignition.

You can later swap this box for a clean loss-on-ignition sketch.

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Animal Physiology Flashcards – FREE Sample

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