Describe the journey of food through the alimentary canal, starting from ingestion in the mouth and ending at egestion at the anus. Include the names of the structures through which food passes and one digestive process that occurs in each structure named.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Food enters the mouth where mechanical digestion by chewing and chemical digestion of starch by salivary amylase occur.
Food is swallowed and travels through the oesophagus by peristaltic waves into the stomach, where proteases chemically digest protein and the stomach churns food.
The chyme enters the small intestine (duodenum and ileum) where pancreatic enzymes and bile chemically digest proteins, lipids and starch, and bile emulsifies fats.
Undigested material moves into the large intestine, where water is reabsorbed and the remaining waste is formed into faeces and expelled through the anus.
Food is swallowed and travels through the oesophagus by peristaltic waves into the stomach, where proteases chemically digest protein and the stomach churns food.
The chyme enters the small intestine (duodenum and ileum) where pancreatic enzymes and bile chemically digest proteins, lipids and starch, and bile emulsifies fats.
Undigested material moves into the large intestine, where water is reabsorbed and the remaining waste is formed into faeces and expelled through the anus.
Examiner tips
- Use the exact terms: mouth, oesophagus, stomach, small intestine, large intestine, anus. Mention one process in each: chewing/amylase, peristalsis/proteases, pancreatic enzymes/bile, water reabsorption.
- common_mistakes
- :
- Mixing up the order of organs or omitting the oesophagus. Failing to name a specific digestive process for each organ.
Mark scheme (4 marks)
- Food enters via the mouth, where physical (mechanical) digestion by teeth breaks food into smaller pieces and/or chemical digestion of starch begins (by amylase in saliva)
- Food passes through the oesophagus by peristalsis into the stomach, where protein is chemically digested by proteases and/or food is churned (physical digestion)
- Food passes into the small intestine (duodenum / ileum), where chemical digestion of proteins, lipids and starch is completed by enzymes from the pancreas / pancreatic juice, and/or bile neutralises stomach acid / bile emulsifies fats
- Undigested material passes into the large intestine where water is reabsorbed, and indigestible waste is egested as faeces through the anus
Key terms in this question
alimentary canal · ingestion · egestion
Related
- All Cambridge International IGCSE Biology (0610) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →