Curriculum Portal

neurologyYou need to know

• Finite resources, such as metal ores and fossil fuels, are used faster than they are replaced by natural processes, so their supplies can run out.
• Renewable resources are replenished by natural processes on a human timescale, but they can still be depleted if used faster than they are replaced.
• Reuse means using a product or material again without substantially changing it, whereas recycling means processing waste materials into materials for new products.
• Recycling metals reduces the need for mining and usually uses less energy than extraction from ores, although collection, sorting, and processing still have environmental impacts.
• Limited supplies of metal ores can be conserved by reusing products, recycling metals, designing longer-lasting products, and replacing metals with suitable alternative materials.
• A life cycle assessment, or LCA, assesses a product’s environmental impacts throughout its life to identify improvements and compare alternatives.
• The main LCA stages are extracting and processing raw materials, manufacturing and packaging, use, and end-of-life disposal or recycling, with transport considered throughout.
• LCA conclusions depend on the quality of the data, the boundaries chosen, and how different impacts are weighted, so comparisons should consider products providing the same service.
• Pure water contains only water molecules, whereas potable water is safe to drink but usually contains dissolved substances.
• Groundwater collects in underground rocks called aquifers and may contain dissolved salts, microorganisms, and other contaminants.
• Groundwater treatment depends on its contaminants and can include filtration to remove suspended solids, but ordinary filtration does not remove dissolved salts.
• Water can be sterilised using chlorine, ozone, or ultraviolet light to kill or inactivate harmful microorganisms.
• Desalination removes dissolved salts from seawater or other saline water using methods such as distillation or reverse osmosis.
• Distillation requires energy for heating, whereas reverse osmosis uses pressure to force water through a partially permeable membrane that rejects most dissolved salts.
• Simple distillation separates water from dissolved salts by evaporating the water and then cooling the vapour so it condenses into a liquid called the distillate.
• At standard atmospheric pressure, pure water boils at 100 °C and freezes at 0 °C, whereas dissolved impurities can alter these temperatures.
• The first stages of sewage treatment include screening to remove large objects and grit removal to separate particles such as sand.
• During sedimentation, suspended solids settle to form sewage sludge, leaving a liquid effluent for further treatment.
• Aerobic biological treatment supplies oxygen so microorganisms can break down organic matter in the sewage effluent, reducing its environmental impact before discharge.
• Anaerobic digestion breaks down sewage sludge without oxygen and produces biogas containing methane, which can be burned as a fuel.

• Classify resources as finite or renewable by comparing their rate of use with their rate of natural replacement.
• Extract values from environmental graphs, charts, and tables using labels, scales, and units, and calculate differences or percentages to support comparisons.
• Evaluate ways to conserve metal ores by comparing reuse, recycling, longer product lifetimes, and substitution in terms of resource use, energy demand, and practical limitations.
• Evaluate a material or product using LCA evidence from each life-cycle stage, making a justified judgement and identifying missing data or subjective weighting.
• Compare filtration, sterilisation, distillation, and reverse osmosis by identifying the contaminants each removes or inactivates and its energy requirements.
• Carry out simple distillation using an electric heat source, a thermometer positioned at the condenser entrance, and a water-cooled condenser, collecting the distillate without sealing the apparatus or boiling the flask dry.
• Assess the purity of a water sample by measuring its boiling point and evaporating a separate small sample to check for dissolved-solid residue, recognising that these tests alone do not establish potability.
• Sequence and explain sewage treatment from screening and grit removal through sedimentation and aerobic treatment, distinguishing the liquid effluent pathway from anaerobic digestion of the sludge.