Food and Nutrition
Year 7 ๐ซ Physiology & Health Nutrients, food tests, and a balanced diet for health.
๐ฅ The Seven Nutrients
A balanced diet must include all seven nutrient groups in appropriate amounts.
| Nutrient | Food sources | Function | Deficiency disease |
|---|---|---|---|
| Carbohydrates | Bread, rice, pasta, sugar | Primary energy source (respiration) | Fatigue, weight loss |
| Proteins | Meat, fish, eggs, pulses | Growth, repair, enzymes, antibodies | Kwashiorkor |
| Fats (lipids) | Butter, oils, nuts | Long-term energy, insulation, cell membranes, fat-soluble vitamins | Vitamin A/D/E/K deficiency |
| Vitamins | Fruit, vegetables, dairy | Various: Vit C โ collagen; Vit D โ Caยฒโบ absorption | Scurvy (C); Rickets (D) |
| Mineral salts | Meat, dairy, leafy veg | Iron โ haemoglobin; Ca โ bones/teeth | Anaemia (iron) |
| Water | Drinks, food | Solvent; transport; regulates temperature | Dehydration |
| Dietary fibre | Wholegrain, fruit, veg | Aids peristalsis; prevents constipation | Constipation; bowel disease |
๐งช Food Tests
You need to know the reagent, method, and positive result for each food test.
| Nutrient | Reagent | Method | Positive result |
|---|---|---|---|
| Starch | Iodine solution | Add drops to food | Blue-black colour |
| Reducing sugars (glucose) | Benedict's solution | Heat in water bath | Brick-red precipitate |
| Protein | Biuret reagent | Add NaOH then CuSOโ | Purple/violet colour |
| Fats (lipids) | Ethanol + water | Shake food in ethanol, add to water | White milky emulsion |
Biuret tests for peptide bonds (present in all proteins and polypeptides), not individual amino acids.
Ready to test yourself? Click the Quiz tab above!
Interactive Demo โ Food and Nutrition
๐ฌ
Interactive demo โ try the Calculate tab for this topic!
Nutrition Analyser