Human Nutrition – Chapter 8
Cambridge O Level Biology 5090 - 2026
HUMAN NUTRITION – CHAPTER 8 STUDY GUIDE
Exam-Focused
Author: HAMZA–Independent Study Notes Author Intended Audience: O Level,
S
IGCSE, GCSE, IB, AP, and A-Level Biology Students Syllabus: Cambridge O Level
Biology 5090 Edition / Date: Version 1.0 | Updated 2026
TE
NO
ZA
M
Highlights of This Study Guide:
HA
Fully aligned with Cambridge O Level Biology 5090
Original, easy-to-understand explanations for every subtopic
Quick revision checks and exam key points for efficient studying
Structured for exam success and digital sale
, Human Nutrition – Chapter 8
Cambridge O Level Biology 5090 - 2026
TABLE OF CONTENTS (Chapter 8 – Human Nutrition)
8.1 Diet
8.1.1 Principal Sources and Dietary Importance of Food Components
S
Carbohydrates: sources, role, energy storage, fiber
Lipids: sources, energy store, insulation, protection, membranes, fat-soluble vitamins
TE
Proteins: sources, growth/repair, enzymes, antibodies, energy source
Vitamins: C and D – sources and functions
Mineral Salts: Calcium and Iron – sources and functions
Fiber: sources and importance
Water: sources and functions
8.1.2 Deficiency Diseases and Symptoms
Vitamin C – Scurvy
Vitamin D – Rickets
NO
Calcium – Rickets and related symptoms
ZA
Iron – Anaemia
8.1.3 Balanced Diet
Definition and components
Factors affecting dietary requirements: age, gender, activity, pregnancy, lactation, health
M
EXAM KEYPOINTS,COMMON EXAM TRAPS, QUICK REVISION CHECK
8.2 Digestion
8.2.1 Main Regions of the Digestive System
HA
Mouth, salivary glands, oesophagus, stomach, small intestine, pancreas, liver, gall bladder, large
intestine
8.2.2 Why Food Must Be Digested
Large vs small molecules, absorption, transport to cells
8.2.3 Physical vs Chemical Digestion
, Human Nutrition – Chapter 8
Cambridge O Level Biology 5090 - 2026
Physical: chewing, churning, bile emulsification
Chemical: enzyme-catalyzed breakdown
8.2.4 Human Teeth
Types: incisors, canines, premolars, molars
S
Structure: enamel, dentine, pulp, cement, gum
8.2.5 Functions of Digestive System Regions
TE
Mouth, salivary glands, stomach, small intestine, liver, gall bladder, pancreas, ileum, colon,
rectum, anus
8.2.6 Digestive Enzymes and End Products
Amylase, maltase, protease (pepsin & trypsin), lipase
8.2.7 Hydrochloric Acid in Stomach
8.2.8 pH and Protease Activity
8.2.9 Role of Bile
8.2.10 Peristalsis
NO
EXAM KEY POINTS, COMMON EXAM TRAPS, QUICK REVISION CHECK
ZA
8.3 Absorption and Assimilation
8.3.1 Absorption in the Small Intestine
Mechanisms: diffusion, osmosis, active transport
8.3.2 Structure of a Villus
M
Columnar epithelial cells, microvilli, capillaries, lacteals, goblet cells
8.3.3 Significance of Villi and Microvilli
8.3.4 Roles of Capillaries and Lacteals
HA
8.3.5 Water Absorption
8.3.6 Hepatic Portal Vein
8.3.7 Assimilation
EXAM KEY POINTS, COMMON EXAM TRAPS, QUICK REVISION CHECK
, Human Nutrition – Chapter 8
Cambridge O Level Biology 5090 - 2026
8 Human Nutrition
8.1 Diet
S
8.1.1 Principal sources and dietary importance of carbohydrates, lipids, proteins,
TE
vitamins, mineral salts, fibre and water
Carbohydrates
NO
Basic Concept: Carbohydrates are organic compounds composed of carbon, hydrogen and
oxygen, with the general formula (CH₂O)ₙ. They are the body’s primary source of energy.
Principal sources:
ZA
·Cereals and grains: rice, wheat, maize, oats
·Root vegetables: potatoes, cassava, yams
·Fruits: bananas, apples, dates
·Sugars: sucrose (table sugar), honey, sweets
M
·Legumes: beans, lentils
Dietary importance:
HA
·Provide immediate energy for cellular activities
·Glucose is the main substrate for respiration
·Excess carbohydrates are converted to glycogen for short-term energy storage in liver and
muscles
Cambridge O Level Biology 5090 - 2026
HUMAN NUTRITION – CHAPTER 8 STUDY GUIDE
Exam-Focused
Author: HAMZA–Independent Study Notes Author Intended Audience: O Level,
S
IGCSE, GCSE, IB, AP, and A-Level Biology Students Syllabus: Cambridge O Level
Biology 5090 Edition / Date: Version 1.0 | Updated 2026
TE
NO
ZA
M
Highlights of This Study Guide:
HA
Fully aligned with Cambridge O Level Biology 5090
Original, easy-to-understand explanations for every subtopic
Quick revision checks and exam key points for efficient studying
Structured for exam success and digital sale
, Human Nutrition – Chapter 8
Cambridge O Level Biology 5090 - 2026
TABLE OF CONTENTS (Chapter 8 – Human Nutrition)
8.1 Diet
8.1.1 Principal Sources and Dietary Importance of Food Components
S
Carbohydrates: sources, role, energy storage, fiber
Lipids: sources, energy store, insulation, protection, membranes, fat-soluble vitamins
TE
Proteins: sources, growth/repair, enzymes, antibodies, energy source
Vitamins: C and D – sources and functions
Mineral Salts: Calcium and Iron – sources and functions
Fiber: sources and importance
Water: sources and functions
8.1.2 Deficiency Diseases and Symptoms
Vitamin C – Scurvy
Vitamin D – Rickets
NO
Calcium – Rickets and related symptoms
ZA
Iron – Anaemia
8.1.3 Balanced Diet
Definition and components
Factors affecting dietary requirements: age, gender, activity, pregnancy, lactation, health
M
EXAM KEYPOINTS,COMMON EXAM TRAPS, QUICK REVISION CHECK
8.2 Digestion
8.2.1 Main Regions of the Digestive System
HA
Mouth, salivary glands, oesophagus, stomach, small intestine, pancreas, liver, gall bladder, large
intestine
8.2.2 Why Food Must Be Digested
Large vs small molecules, absorption, transport to cells
8.2.3 Physical vs Chemical Digestion
, Human Nutrition – Chapter 8
Cambridge O Level Biology 5090 - 2026
Physical: chewing, churning, bile emulsification
Chemical: enzyme-catalyzed breakdown
8.2.4 Human Teeth
Types: incisors, canines, premolars, molars
S
Structure: enamel, dentine, pulp, cement, gum
8.2.5 Functions of Digestive System Regions
TE
Mouth, salivary glands, stomach, small intestine, liver, gall bladder, pancreas, ileum, colon,
rectum, anus
8.2.6 Digestive Enzymes and End Products
Amylase, maltase, protease (pepsin & trypsin), lipase
8.2.7 Hydrochloric Acid in Stomach
8.2.8 pH and Protease Activity
8.2.9 Role of Bile
8.2.10 Peristalsis
NO
EXAM KEY POINTS, COMMON EXAM TRAPS, QUICK REVISION CHECK
ZA
8.3 Absorption and Assimilation
8.3.1 Absorption in the Small Intestine
Mechanisms: diffusion, osmosis, active transport
8.3.2 Structure of a Villus
M
Columnar epithelial cells, microvilli, capillaries, lacteals, goblet cells
8.3.3 Significance of Villi and Microvilli
8.3.4 Roles of Capillaries and Lacteals
HA
8.3.5 Water Absorption
8.3.6 Hepatic Portal Vein
8.3.7 Assimilation
EXAM KEY POINTS, COMMON EXAM TRAPS, QUICK REVISION CHECK
, Human Nutrition – Chapter 8
Cambridge O Level Biology 5090 - 2026
8 Human Nutrition
8.1 Diet
S
8.1.1 Principal sources and dietary importance of carbohydrates, lipids, proteins,
TE
vitamins, mineral salts, fibre and water
Carbohydrates
NO
Basic Concept: Carbohydrates are organic compounds composed of carbon, hydrogen and
oxygen, with the general formula (CH₂O)ₙ. They are the body’s primary source of energy.
Principal sources:
ZA
·Cereals and grains: rice, wheat, maize, oats
·Root vegetables: potatoes, cassava, yams
·Fruits: bananas, apples, dates
·Sugars: sucrose (table sugar), honey, sweets
M
·Legumes: beans, lentils
Dietary importance:
HA
·Provide immediate energy for cellular activities
·Glucose is the main substrate for respiration
·Excess carbohydrates are converted to glycogen for short-term energy storage in liver and
muscles
