Learning focus
Build precise biological explanations, interpret diagrams and data, and connect structure, process and practical evidence.
Pancreatic secretion
The pancreas releases an alkaline fluid into the duodenum. It contains amylase, protease and lipase. The alkaline conditions help neutralise stomach acid and allow intestinal enzymes to function effectively.
Carbohydrate digestion
Pancreatic amylase continues the breakdown of starch to maltose. Maltase, associated with the small-intestinal lining, converts maltose to glucose. Glucose is small, soluble and ready for absorption.
Protein digestion
Proteases such as trypsin act in the duodenum and small intestine. They break proteins and peptides to amino acids. Amino acids are absorbed into blood capillaries and used for synthesis of new proteins.
Lipid digestion
Lipase acts on emulsified lipid droplets, producing fatty acids and glycerol. These products enter epithelial cells and are transported mainly through lacteals before joining the blood circulation.
Specificity and conditions
Each enzyme has a complementary active site and acts on a particular substrate. Temperature and pH affect enzyme activity. Therefore, digestion depends not only on enzyme presence but also on suitable physical and chemical conditions.
Practical or data skill
Create an enzyme-substrate-product flow chart from memory and check it against the syllabus list. Then explain why amylase and maltase cannot be treated as interchangeable enzymes.
Examination tip
Use the correct pairs: starch → maltose by amylase; maltose → glucose by maltase.
Review questions and suggested answers
Question 1
Which three enzyme types are present in pancreatic secretion?
Suggested answer
Amylase, protease and lipase.
Question 2
What does maltase produce?
Suggested answer
Glucose.
Question 3
Why is pancreatic secretion alkaline?
Suggested answer
To help neutralise acidic stomach contents and provide suitable pH for intestinal enzymes.
