Who this is for: Cambridge IGCSE Biology (0610) students who can label villi but lose marks explaining adaptations, naming absorbed molecules, or distinguishing diffusion from active transport for glucose.
What query it owns: how to understand and revise absorption in Cambridge IGCSE Biology.
Why this is safe: this page owns the absorption revision-guide angle, while Tutopiya’s Absorption subtopic page owns the learning resource and the free Absorption quiz owns the practice.

Absorption is the uptake of digested food molecules from the ileum into the blood (and lacteals for fats). Cambridge IGCSE Biology (0610) tests villus adaptations — large surface area, thin wall, good blood supply — and whether glucose moves by diffusion or active transport depending on concentration. This guide covers the syllabus content and exam wording.

Key takeaways

• Most absorption occurs in the ileum (small intestine).
• Villi and microvilli increase surface area; walls are one cell thick (short diffusion distance).
• Capillaries carry glucose and amino acids; lacteals (lymph) carry fatty acids and glycerol.
• Glucose and amino acids → blood → liver; fats → lacteals → lymph → blood.
• Active transport absorbs glucose when gut concentration is low relative to blood.

What is absorption in Cambridge IGCSE Biology?

Absorption is the movement of soluble digested molecules through the wall of the ileum into the circulatory system. Villi provide a large surface area and a rich capillary network so molecules reach the blood quickly. Assimilation — using absorbed molecules in cells — happens after absorption.

You can read the full explanation, worked examples and notes on Tutopiya’s Absorption subtopic page before you attempt questions.

The core ideas you must master

Adaptation	How it helps absorption	Exam phrase
Many villi	Large surface area	”Increases surface area”
Microvilli on epithelium	Even larger surface area	”Microvilli”
Thin epithelium (one cell thick)	Short diffusion distance	”Thin wall”
Dense capillary network	Quick removal maintains gradient	”Good blood supply”
Lacteals in villi	Absorb fats into lymph	”Lacteal”

Molecules absorbed and their routes

Molecule	Route after absorption	Transport mechanism
Glucose	Capillary → hepatic portal vein → liver	Diffusion and active transport
Amino acids	Capillary → liver	Diffusion
Fatty acids + glycerol	Re-formed as fat in epithelium → lacteal	Diffusion into lacteal
Minerals / vitamins	Blood	Mainly diffusion

Absorption in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical absorption stem
Describe	Villus structure / adaptations	”Describe how villi are adapted.”
Explain	Cause and effect	”Explain how villi increase absorption rate.”
State	Location or route	”State where glucose is absorbed.”
Suggest	Apply transport knowledge	”Suggest how glucose is absorbed when gut concentration is low.”

Worked exam-style stems (how to answer the wording)

1. “Describe how the ileum is adapted for absorption.” Villi increase surface area; microvilli further increase it; thin wall → short diffusion distance; capillaries maintain concentration gradient. Reward: at least three adaptations with explanations.
2. “Explain why active transport is needed to absorb glucose.” When glucose concentration in ileum lumen is lower than in blood, diffusion cannot continue → active transport moves glucose against gradient using energy from respiration. Reward: gradient + energy.
3. “State the function of a lacteal.” Absorbs products of fat digestion into the lymph. Reward: fats / lymph link.

When you can recognise the wording instantly, work the full set on the Human Nutrition topical past paper questions and the Absorption quiz.

How absorption connects to the rest of the syllabus

Absorption follows Chemical Digestion in the Digestive System and links to active transport in Movement into and out of Cells. The Cambridge IGCSE Biology resource hub links every Human Nutrition subtopic.

Common mistakes students make

• Saying absorption happens in the stomach (ileum is the main site).
• Listing villi adaptations without explaining how each increases rate.
• Forgetting lacteals for fat absorption.
• Saying all glucose absorption is diffusion only.
• Confusing absorption with assimilation or egestion.

When you need more support

If villus adaptation questions keep costing marks, work through the Human Nutrition topical past paper questions and the Absorption quiz, then get focused help from a Cambridge IGCSE Biology tutor.

Frequently asked questions

Is absorption hard in Cambridge IGCSE Biology? Villus structure is well-rehearsed in textbooks — marks are lost when students omit microvilli, lacteals or active transport for glucose.

Where are fats absorbed? Into lacteals in villi, then into the lymphatic system before entering the blood.

Why is a good blood supply important? It removes absorbed molecules quickly, maintaining a concentration gradient for continued diffusion.

How do I revise absorption effectively? Draw and label a villus, list adaptations with explanations, practise glucose transport stems, then take the Absorption quiz.

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