2.5Structures and Functions in Living Organisms

Nutrition — Edexcel Modular - OL Revision Notes & Topical Questions

20 min read 30 parts Lesson 5 of 12 2 quizzes

📚 Edexcel Modular - OL Hub / Topical Revision

0%read

Lesson summary

Nutrition Edexcel O Level Modular Biology notes: understand the process of photosynthesis and its importance in the conversion of light energy to chemical energyStomach acid kills microbes and gives pepsin its optimum pH.Villi have thin walls, capillaries and lacteals.Large intes…

Nutrition Edexcel O Level Modular Biology: what to do next
Mechanical digestion
Chemical digestion
Give / State / Name
Evaluate / Assess
Keywords the mark scheme looks for in this lesson

Part 1 of 6Key ideas

Key ideas

Stomach acid kills microbes and gives pepsin its optimum pH.

Villi have thin walls, capillaries and lacteals.

Large intestine absorbs water.

Part 2 of 6Syllabus points

understand the process of photosynthesis and its importance in the conversion of light energy to chemical energy

know the word equation and the balanced chemical symbol equation for photosynthesis

understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesis

describe the structure of the leaf and explain how it is adapted for photosynthesis

understand that plants require mineral ions for growth, and that magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acids

practical: investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyll

understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre

identify the sources and describe the functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and dietary fibre as components of the diet

understand how energy requirements vary with activity levels, age and pregnancy

describe the structure and function of the human alimentary canal, including the mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreas

understand how food is moved through the gut by peristalsis

understand the role of digestive enzymes, including the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipases

understand that bile is produced by the liver and stored in the gall bladder

understand the role of bile in neutralising stomach acid and emulsifying lipids

understand how the small intestine is adapted for absorption, including the structure of a villus

Part 3 of 6Process & sequence

Mouth
Oesophagus (peristalsis)
Stomach
Small intestine (absorption)
Large intestine (water)
Rectum, anus

Nutrients

Carbohydrates – energy

Proteins – growth

Lipids – energy store

Vitamins, minerals, fibre, water

Part 4 of 6Summary

Summary

Bile emulsifies fats.

Most absorption occurs in the small intestine.

Part 5 of 6Keep going

Nutrition Edexcel O Level Modular Biology: what to do next

These Nutrition Edexcel O Level Modular Biology notes covered the key ideas, worked examples and exam technique for this topic. Check your Nutrition Edexcel O Level Modular Biology understanding with the practice questions below, then reread any Nutrition Edexcel O Level Modular Biology point you were unsure about before moving on.

Practice: Nutrition Edexcel O Level Modular Biology practice questions

Previous lesson: 2.4 Movement of substances into and out of cells — Notes

Next lesson: 2.6 Respiration — Notes

Course: Edexcel Modular - OL — all units

Official syllabus: Pearson Edexcel International GCSEs

Part 6 of 6Compare: Compare

Digestive enzymes
Enzyme	Made in	Acts in	Substrate	Product	Optimum pH
Salivary amylase	Salivary glands	Mouth	Starch	Maltose	7
Pepsin	Stomach	Stomach	Protein	Peptides	2
Pancreatic amylase	Pancreas	Small intestine	Starch	Maltose	8
Trypsin	Pancreas	Small intestine	Protein	Peptides	8
Lipase	Pancreas	Small intestine	Lipids	Fatty acids + glycerol	8
Maltase	Small intestine wall	Small intestine	Maltose	Glucose	8

Key terms

Command terms

Give / State / Name

Recall a fact; one idea per mark.

Define

Give the exact meaning using the specification keywords.

Describe

Give an account of what happens / the pattern in data, quoting values; no reasons needed.

Explain

Give reasons with linked statements (cause → effect). Each linked step is usually a separate marking point.

Suggest

Use knowledge in a new context; more than one answer may be accepted.

Compare

Similarities and differences; each point must refer to both items.

Calculate

Show working; include units; check significant figures. Method marks are given even if the final answer is wrong.

Discuss

Explore the issue from different angles and link the points.

Evaluate / Assess

Weigh strengths and weaknesses and reach a supported judgement.

Deduce

Draw a conclusion from the information given.

Justify

Support a statement/choice with evidence.

Exam technique

Keywords the mark scheme looks for in this lesson

Digestion · Mechanical digestion · Chemical digestion · Amylase · Protease · Lipase · Bile · Villi

Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.

How to get full marks (examiner guidance)

Use specification keywords exactly (e.g. eukaryotic/prokaryotic, enzyme–substrate complex, active site, complementary).

Link ideas

Link ideas for “explain” each marking point is usually a cause → consequence step; unlinked facts often score nothing.

Use the information in the question

“discuss/evaluate” answers must use the data provided and match the number of marks.

Convert units carefully (mg → g, cm³ → dm³) and show working for calculations.

Avoid vague words

“it”, “stuff”, “things”, “goes up”, “energy is made”. Name the substance and the process.

Do not extrapolate a graph line beyond the data or to zero unless asked.

Six-mark extended responses are marked on content AND a logical, linked line of reasoning.

Last updated: 11 October 2026