Explain how bioleaching works and its role in metal extraction.

Bioleaching involves using bacteria to break down metal compounds in ores, producing a leachate solution that contains dissolved metals. This method allows for the extraction of metals from low-grade ores and reduces environmental impact compared to traditional mining.

A strong answer should directly address the approved learning objective to evaluate biological methods of metal extraction from information provided. (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.