OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

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What is a key function of enzymes in washing powder?

To cause clothes to become brighter
To chemically break down stains
To physically scrub the dirt from clothing
To mask odors in clothing

The correct answer is: To chemically break down stains

Enzymes play a crucial role in the effectiveness of washing powders primarily by chemically breaking down stains. In the context of laundry, enzymes can target specific types of stains, such as proteins in food, fats in grease, or starches in certain soils. They act as biological catalysts that accelerate chemical reactions, making it easier for the washing machine to remove these stains at lower temperatures. For example, proteases break down protein-based stains like blood or egg, while lipases target greasy stains. This biochemical action enhances the cleaning process, allowing for better stain removal without the need for high washing temperatures, which can save energy and protect fabrics. Other options relate to functions that do not align with how enzymes work. Brightening agents typically involve optical brighteners rather than enzymatic activity, physical scrubbing is done by the mechanical action of the washer, and masking odors involves fragrance agents, rather than enzymes.