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

Where does the enzymatic breakdown of carbohydrates begin?

1. Small intestine

2. Stomach

3. Mouth

4. Pancreas

The correct answer is: Mouth

The enzymatic breakdown of carbohydrates begins in the mouth, where saliva is secreted by the salivary glands. This saliva contains an enzyme known as amylase, which starts the process of breaking down starches into simpler sugars like maltose. The action of chewing also helps to mix food thoroughly with saliva, allowing the amylase to function more effectively. While the small intestine and pancreas are involved in further digestion and carbohydrate breakdown—through pancreatic amylase and other enzymes—the initial enzymatic process specifically commences in the mouth. This makes the mouth the correct answer for where carbohydrates begin their breakdown. In the stomach, no significant carbohydrate digestion occurs as the acidic environment is not ideal for amylase, reinforcing the importance of the mouth in the digestive process.