Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
What Are Nutrients?
Food contains substances called nutrients that our body needs to:
- Get energy for daily activities
- Grow and repair body tissues
- Stay healthy and fight diseases
Main Components of Food
1. Carbohydrates
- Provide energy for daily activities.
- Two types: Starch and Sugar.
- Rich sources: Rice, wheat, bread, potato, maize, sugar, jaggery.
Test for starch: Add iodine solution → turns blue-black if starch is present.
2. Proteins
- Needed for growth and repair of body tissues.
- Called the "building blocks" of the body.
- Rich sources: Pulses (dal), milk, eggs, meat, fish, soyabean, nuts.
Test for protein: Add copper sulphate + caustic soda → turns violet/purple if protein is present.
3. Fats
- Provide energy (more than carbohydrates).
- Also keep body warm and protect organs.
- Rich sources: Butter, ghee, oil, nuts, meat, cheese, coconut.
Test for fat: Rub food on plain paper → leaves a translucent (oily) mark if fat is present.
4. Vitamins
- Protect the body from diseases.
- Needed in small amounts.
- Do not provide energy but are essential.
| Vitamin | Function | Source | Deficiency Disease |
|---|---|---|---|
| A | Good eyesight, skin | Carrot, milk, egg, papaya | Night blindness |
| B1 (Thiamine) | Nerves, energy | Whole grains, pulses | Beri-beri |
| B2 (Riboflavin) | Growth | Milk, eggs, green vegetables | Sores on skin/lips |
| C | Healthy gums, healing | Amla, orange, lemon, guava | Scurvy |
| D | Strong bones and teeth | Sunlight, fish oil, milk | Rickets |
5. Minerals
- Needed in small amounts for various body functions.
| Mineral | Function | Source | Deficiency |
|---|---|---|---|
| Iron | Makes haemoglobin in blood | Spinach, liver, jaggery, meat | Anaemia |
| Calcium | Strong bones and teeth | Milk, cheese, green vegetables | Weak bones, tooth decay |
| Iodine | Thyroid gland function | Iodised salt, sea food | Goitre (swelling in neck) |
6. Water
- Makes up about 70% of the human body.
- Needed for digestion, absorbing nutrients, removing waste.
- Source: Drinking water, fruits, vegetables.
7. Roughage (Dietary Fibre)
- Not digested by the body but helps in smooth movement of food through intestines.
- Prevents constipation.
- Source: Fruits, vegetables, whole grains, pulses.
Deficiency Diseases — Quick Reference
| Deficiency | Disease |
|---|---|
| Vitamin A | Night blindness |
| Vitamin B1 | Beri-beri |
| Vitamin C | Scurvy |
| Vitamin D | Rickets |
| Iron | Anaemia |
| Iodine | Goitre |
| Protein | Kwashiorkor (in children) |
| Overall food | Marasmus (in children) |
Balanced Diet
A balanced diet includes:
- Enough carbohydrates and fats for energy
- Enough proteins for growth
- Vitamins and minerals to stay healthy
- Water and roughage for body functions
No single food contains all nutrients. That is why we should eat a variety of foods every day.
Obesity and Overeating
- Eating too much fat and carbohydrate leads to obesity.
- Obesity leads to diseases like heart problems, diabetes.
- A good diet means the right amount — not too much, not too little.
NCERT Activity — Food Tests Summary
| Nutrient | Test | Positive Result |
|---|---|---|
| Starch | Iodine solution | Blue-black colour |
| Protein | Copper sulphate + caustic soda | Violet/purple colour |
| Fat | Rub on plain paper | Translucent (oily) patch |
Exam Tips
- Learn all deficiency diseases — at least 4–5 pairs for 3-mark questions.
- Know the three food tests (iodine, copper sulphate, paper test) with what colour/result indicates presence.
- Balanced diet definition should mention all nutrients and right amounts.
- Roughage does not provide nutrition but aids digestion — this difference is often asked.
Frequently Asked Questions
The main nutrients are: Carbohydrates (energy), Proteins (growth and repair), Fats (energy store), Vitamins (protect from disease), Minerals (body functions), Water (all body processes), and Roughage/Dietary fibre (aids digestion).