Science — AI-generated practice question

Mouth: Food is crushed by teeth and mixed with saliva secreted by salivary glands. Saliva contains salivary amylase which breaks down starch into simple sugars. The tongue helps mix food thoroughly.

Oesophagus: Food is pushed down to the stomach by rhythmic peristaltic movements of the canal muscles.

Stomach: Gastric glands secrete hydrochloric acid, enzyme pepsin, and mucus. HCl creates an acidic medium for pepsin to digest proteins. Mucus protects the stomach lining from acid damage.

Small Intestine: The food (now acidic) receives bile juice from the liver, which makes it alkaline and emulsifies fats. The pancreas secretes trypsin (proteins) and lipase (fats). Intestinal glands secrete intestinal juice that finally converts proteins → amino acids, carbohydrates → glucose, fats → fatty acids and glycerol.

Source: Chapter 5, Section 5.2.4

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• Award marks are typically split: 1 mark each for mouth, oesophagus, stomach, small intestine (role of bile + pancreas), and small intestine (final digestion/absorption).
• Always name the specific enzyme and its substrate — examiners look for this.
• "Emulsification" is a key term for bile's action on fats; don't miss it.
• Keep absorption (villi) brief or skip if word count is tight — the question asks about digestion, not absorption.