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Quick Summary
Nutrition is the process of obtaining and using food for growth, energy, and maintenance. Class 9 covers the six nutrient classes, their sources and functions, deficiency diseases, and the concept of a balanced diet. Deficiency disease tables are frequently asked in board exams.
Key Definitions
- Nutrition: Process of taking in and using food for body functions.
- Nutrients: Chemical substances in food needed for body processes.
- Malnutrition: Condition resulting from eating too much, too little, or wrong types of nutrients.
- Balanced Diet: Diet containing all nutrients in adequate amounts.
- Calorie (kcal): Unit of energy in food.
- Basal Metabolic Rate (BMR): Minimum energy needed to maintain basic body functions at rest.
- Obesity: Condition of excess body fat; BMI > 30.
- Body Mass Index (BMI): Weight (kg) / Height (m)². Normal: 18.5–24.9.
Nutrients and Their Functions
| Nutrient | Function | Sources |
|---|---|---|
| Carbohydrates | Energy (4 kcal/g) | Rice, wheat, sugar, fruits |
| Proteins | Growth, repair, enzymes (4 kcal/g) | Pulses, egg, meat, milk |
| Fats | Energy storage, fat-soluble vitamins (9 kcal/g) | Oil, butter, nuts |
| Vitamins | Regulate metabolic processes | Fruits, vegetables, dairy |
| Minerals | Build bones, teeth, blood | Milk (Ca), meat (Fe), seafood (I) |
| Water | Transport, chemical reactions, temperature control | Drinking water, fruits |
Vitamins and Deficiency Diseases
| Vitamin | Deficiency Disease | Source |
|---|---|---|
| A | Night blindness, Xerophthalmia | Carrot, papaya, eggs |
| B₁ (Thiamine) | Beriberi | Whole grains, legumes |
| B₃ (Niacin) | Pellagra | Meat, fish, peanuts |
| C (Ascorbic acid) | Scurvy | Citrus fruits, amla |
| D | Rickets (children), Osteomalacia (adults) | Sunlight, fish liver oil |
| K | Excessive bleeding | Green leafy vegetables |
Mineral Deficiency Diseases
| Mineral | Deficiency | Source |
|---|---|---|
| Iron | Anaemia | Green leafy vegetables, liver |
| Iodine | Goitre, Cretinism | Iodised salt, seafood |
| Calcium | Weak bones, dental problems | Milk, cheese |
| Fluorine | Dental decay | Fluoridated water, tea |
Protein Deficiency Diseases
- Kwashiorkor: Protein deficiency in children (adequate calories but inadequate protein) — swollen belly, skin lesions.
- Marasmus: Total calorie and protein deficiency — extreme wasting, muscle loss.
Important Questions
One Mark
- Name the deficiency disease caused by lack of Vitamin C.
- What is the BMI range for a healthy adult?
- Define malnutrition.
- Which mineral prevents goitre?
- How many kilocalories are provided by 1 gram of fat?
Short Answer (3 marks)
- Distinguish between Kwashiorkor and Marasmus.
- Name four vitamins and their deficiency diseases.
- What is a balanced diet? List its components with approximate percentages.
Long Answer (5 marks)
- Describe the six classes of nutrients with functions and sources. Which two cause the most common deficiency diseases in India?
- Explain five vitamin deficiency diseases with their causes, symptoms, and prevention.
Common Mistakes
- Confusing fat energy (9 kcal/g) with carbohydrate/protein energy (4 kcal/g) — fat gives more than double.
- Confusing Kwashiorkor (protein only deficient) with Marasmus (both protein and calories deficient).
- Forgetting that Vitamin D is made from sunlight — it is unique among vitamins.
Revision Checklist
- [ ] Know functions of all 6 nutrient classes
- [ ] Know at least 6 vitamin deficiency diseases
- [ ] Know mineral deficiency diseases (Fe, I, Ca)
- [ ] Understand difference between Kwashiorkor and Marasmus
- [ ] Know BMI formula and normal range
Frequently Asked Questions
The six classes of nutrients are: Carbohydrates (energy, 4 kcal/g), Proteins (growth and repair, 4 kcal/g), Fats (energy storage, 9 kcal/g), Vitamins (regulate body processes), Minerals (build body structures), and Water (transport, reactions, temperature regulation).