IP Biology Notes: Nutrition in Humans (Upper Sec 04)

For Integrated Programme students: Your current school materials, teacher instructions, and assessment scope take precedence because IP topic sequence and depth vary by school. This is an Eclat IP guide, not the O-Level / SEC G3 exam-track guide.

How this chapter applies

• Eclat core: digestion, peristalsis, digestive enzymes, absorption by villi, the hepatic portal vein, liver functions, alcohol effects, and answer sequencing form the main route.
• School-sensitive extension: micelle detail, wider nutritional biochemistry, and advanced regulation of digestion should be used only where the current school teaches them.
• 2027 national comparison: K325 Topic B4 covers the digestive system, peristalsis, enzymes, villus absorption, hepatic portal transport, liver functions including hormone breakdown, and alcohol effects.
• Check your school: enzyme lists, bile detail, assimilation depth, and the expected treatment of alcohol-related social implications can differ.
• Exam-track route: use the separate O-Level and SEC G3 Biology notes for K325 topic ownership.

The core idea is simple: Nutrition questions follow food from digestion to absorption and use.

Use it as a working check: Track the organ, enzyme, product, and transport route. Separate digestion, absorption, assimilation, and egestion in your answers.

Then go one layer deeper: Example: starch becomes maltose, then glucose. Glucose enters villus capillaries and travels through the hepatic portal vein to the liver.

What you must know

• Digestive organs: mouth (mastication, saliva amylase), oesophagus (peristalsis), stomach (acid, protease/pepsin), small intestine (bile, pancreatic enzymes, intestinal enzymes), large intestine (water absorption), rectum/anus (storage/egestion).
• Enzymes: amylase → maltose; maltase → glucose; protease/trypsin → peptides/amino acids; lipase → fatty acids + glycerol; bile emulsifies fats (mechanical).
• Villi: large surface area (folds, microvilli), thin epithelium, rich capillary network, lacteal for fats; hepatic portal vein carries absorbed sugars/amino acids to liver.
• Liver roles: converts glucose to glycogen and back, deaminates amino acids to form urea, breaks down alcohol and hormones, and produces bile for fat digestion.
• Alcohol effects: short term (slower reaction, impaired judgment), long term (fatty liver, cirrhosis); social/legal impacts.

Enzyme and bile checkpoint

For digestion questions, name the large food molecule first, then track the enzyme and product. Treat bile as a helper, not as an enzyme.