What are two alternative methods for extracting copper from low-grade ores?

Two alternative methods for extracting copper from low-grade ores are phytomining, which uses plants to absorb metal compounds from the soil, and bioleaching, which employs bacteria to produce leachate solutions containing metal compounds.

A strong answer should directly address the approved learning objective to explain why new copper extraction methods are needed as high-grade copper ores become scarce. (HT only). This question belongs to Alternative methods of extracting metals within Using the Earth's resources and obtaining potable water, so the response should use that exact curriculum context rather than a generic statement. The answer is correct when it names the key idea, explains the link to HT only, and keeps the wording specific to AQA GCSE revision.