Cells along the inner wall of the stomach secrete roughly 2 litres of hydrochloric acid every day. This helps to kill bacteria and aids in digestion, by providing the correct pH for enzymes in the stomach to work. Hydrochloric acid is commonly used to remove rust and scale from steel sheets and coils, and is also found in some cleaning supplies, including toilet-bowl cleaners. To protect itself from the corrosive acid, the stomach lining has a thick coating of mucus. The stomach has to produce a new coat of mucus every two weeks!
GCSE scientists you need to be able to explain how enzymes are needed in the digestive system. You also need to describe how to investigate enzyme activity. Try Part 2 of our “How to work with Enzymes” revision guide. It includes exam questions, and answers for you to check your understanding.
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