Chemical digestion
Cambridge IGCSE Biology (0610) · Unit 7: Human nutrition · 10 flashcards
Chemical digestion is topic 7.4 in the Cambridge IGCSE Biology (0610) syllabus , positioned in Unit 7 — Human nutrition , alongside Diet, Digestive system and Physical digestion. In one line: Chemical digestion is the process of breaking down large, insoluble food molecules into small, soluble molecules. This breakdown is achieved through enzymatic hydrolysis.
This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical).
The deck below contains 10 flashcards — 4 definitions, 4 key concepts and 2 process cards — covering the precise wording mark schemes reward. Use the 4 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.
Chemical digestion
Chemical digestion is the process of breaking down large, insoluble food molecules into small, soluble molecules. This breakdown is achieved through enzymatic hydrolysis.
What the Cambridge 0610 syllabus says
Official 2026-2028 specThese are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.
- Describe Describe chemical digestion as the breakdown of large insoluble molecules into small soluble molecules
- State State the role of chemical digestion in producing small soluble molecules that can be absorbed
- Describe Describe the functions of enzymes as follows: (a) amylase breaks down starch to simple reducing sugars (b) proteases break down protein to amino acids (c) lipase breaks down fats and oils to fatty acids and glycerol
- State State where, in the digestive system, amylase, protease and lipase are secreted and where they act
- Describe Describe the functions of hydrochloric acid in gastric juice, limited to killing harmful microorganisms in food and providing an acidic pH for optimum enzyme activity
- Describe Describe the digestion of starch in the digestive system: (a) amylase breaks down starch to maltose (b) maltase breaks down maltose to glucose on the membranes of the epithelium lining the small intestine Supplement
- Describe Describe the digestion of protein by proteases in the digestive system: (a) pepsin breaks down protein in the acidic conditions of the stomach (b) trypsin breaks down protein in the alkaline conditions of the small intestine Supplement
- Explain Explain that bile is an alkaline mixture that neutralises the acidic mixture of food and gastric juices entering the duodenum from the stomach, to provide a suitable pH for enzyme action Supplement
What is chemical digestion?
Chemical digestion is the process of breaking down large, insoluble food molecules into small, soluble molecules. This breakdown is achieved through enzymatic hydrolysis.
What role does chemical digestion play in nutrient absorption?
Chemical digestion produces small, soluble molecules that can be absorbed into the bloodstream. These molecules (
What is the function of amylase, and what does it break down?
Amylase is an enzyme that breaks down starch into smaller sugars, specifically maltose. This process begins in the mouth with salivary amylase and continues in the small intestine with pancreatic amylase.
What is the function of proteases, and what do they break down?
Proteases are enzymes that break down proteins into amino acids. Examples include pepsin in the stomach and trypsin in the small intestine, each working under different pH conditions.
What is the function of lipase, and what does it break down?
Lipase is an enzyme that breaks down fats and oils (lipids) into fatty acids and glycerol. Pancreatic lipase, secreted by the pancreas into the small intestine, is a key example.
Where are amylase, protease, and lipase secreted, and where do they act?
Amylase is secreted in the mouth and pancreas, acting in the mouth and small intestine. Proteases are secreted in the stomach and pancreas, acting in the stomach and small intestine. Lipase is secreted in the pancreas, acting in the small intestine.
What are the two main functions of hydrochloric acid in gastric juice?
Hydrochloric acid (HCl) in gastric juice kills harmful microorganisms ingested with food. It also provides an acidic environment (low pH) that is optimal for the activity of pepsin, a protease enzyme.
Describe the digestion of starch in the small intestine, including the role of maltase.
Amylase breaks down starch into maltose. Maltase, an enzyme located on the epithelial lining of the small intestine, then breaks down maltose into glucose. Glucose is then absorbed into the bloodstream.
Describe the roles of pepsin and trypsin in protein digestion.
Pepsin, found in the stomach, breaks down proteins into smaller peptides in acidic conditions. Trypsin, secreted by the pancreas into the small intestine, further breaks down these peptides into amino acids in alkaline conditions.
What is the function of bile in digestion?
Bile is an alkaline mixture produced by the liver and stored in the gall bladder. It neutralizes the acidic chyme entering the duodenum from the stomach, creating a suitable pH for enzymes like pancreatic lipase to function effectively.
Key Questions: Chemical digestion
What is chemical digestion?
Chemical digestion is the process of breaking down large, insoluble food molecules into small, soluble molecules. This breakdown is achieved through enzymatic hydrolysis.
What is the function of amylase, and what does it break down?
Amylase is an enzyme that breaks down starch into smaller sugars, specifically maltose. This process begins in the mouth with salivary amylase and continues in the small intestine with pancreatic amylase.
What is the function of proteases, and what do they break down?
Proteases are enzymes that break down proteins into amino acids. Examples include pepsin in the stomach and trypsin in the small intestine, each working under different pH conditions.
What is the function of lipase, and what does it break down?
Lipase is an enzyme that breaks down fats and oils (lipids) into fatty acids and glycerol. Pancreatic lipase, secreted by the pancreas into the small intestine, is a key example.
More topics in Unit 7 — Human nutrition
Chemical digestion sits alongside these Biology decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 0610 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Key terms covered in this Chemical digestion deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
Related Biology guides
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