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Tamil Nadu (TNBSE)Class 4 Science★ 5-6 marks in TN Class 4 Term 2 exams — nutrients deeper dive, balanced diet, food preservation methods

Food

Samacheer Kalvi (TN State Board) Class 4 Science — Chapter 5, Food. Nutrients, food groups and balanced diet. Study notes, key concepts, worked examples, practice questions and quick revision for exam preparation.

⏱ 12 min readMedium difficulty✓ Free · NCERT-aligned

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By the end of this chapter you'll be able to…

1Name the 5 nutrients and state deficiency diseases: lack of Vitamin A → night blindness; Vitamin C → scurvy (bleeding gums); Vitamin D → rickets (weak bones); Iron → anaemia; Iodine → goitre; Protein → kwashiorkor
2Explain food preservation: why food spoils (microorganisms — bacteria and fungi), and 6 methods to preserve food — drying, refrigeration/freezing, pickling (salt/oil/vinegar), canning, adding sugar (jam/murabba), vacuum packing
3Give Tamil cultural examples: vathal (sun-dried vegetables), pickle/oorugai (salt+oil preservation), uppu paruppu (salted)

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Why this chapter matters

Class 4 Food moves from identifying nutrients to understanding food preservation — a critical life skill in a tropical country like India where food spoils quickly. Children learn traditional preservation methods (drying, pickling, fermenting) that Tamil culture has practised for centuries, alongside modern methods (refrigeration, canning, vacuum packing). They also learn about deficiency diseases — what happens when you don't get enough of a specific nutrient — which connects back to the balanced diet concept from Class 3 with real health consequences.

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Food — Class 4 Science (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 4 Science, Chapter 5. Nutrients, food groups and balanced diet.

1. About this chapter

This chapter covers Food as part of the Class 4 Samacheer Kalvi Science curriculum. It deals with nutrients, food groups and balanced diet and builds conceptual understanding essential for the TN School Term Exam.

By the end of this chapter, students will be able to:

Identify major food groups
Explain the role of each nutrient

2. Key concepts

Concept 1: Identify major food groups.
Concept 2: Explain the role of each nutrient.

3. Important terms and formulas

Term / Formula	Description
Identify major food groups…	Identify major food groups
Explain the role of…	Explain the role of each nutrient

4. Worked examples

Example 1. Applying a key concept from this chapter.

Solution: Identify the relevant principle → apply the formula or rule → state the answer with correct units.

Example 2. A typical exam-style question on food.

Solution: Break the problem into steps, use the appropriate formula and verify the answer.

5. Common mistakes

Mistake: Skipping units or forgetting to state them. Fix: Always write units alongside every quantity and answer.
Mistake: Confusing similar terms or concepts in this chapter. Fix: Make a comparison table of the terms during revision.

6. Practice (exam-style)

Define the main term or principle covered in Chapter 5.
Give two real-life examples related to food.
Solve a short numerical or descriptive question from this chapter.
State one important formula and explain each symbol.

7. Answer key (hints)

Refer to section 2 (Key concepts) above for the definition.
Examples should be drawn from daily experience and local context.
Apply the formula from section 3, show all steps clearly.
Formula with units — refer to the textbook glossary for symbol meanings.

8. Quick revision

Class 4 Science — Chapter 5: Food.
Core idea: Nutrients, food groups and balanced diet.
Key outcomes: Identify major food groups; Explain the role of each nutrient.
Always revise diagrams / tables from the Samacheer Kalvi textbook before the exam.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Deficiency diseases

Vitamin A deficiency → Night blindness (cannot see in dim light). Sources: carrot, papaya, mango, green leafy vegetables, fish liver oil. Vitamin C deficiency → Scurvy (bleeding gums, slow wound healing). Sources: amla (Indian gooseberry — richest source!), lemon, orange, guava. Vitamin D deficiency → Rickets (soft, bent bones in children). Sources: sunlight (body makes Vit D when skin is exposed), milk, egg yolk, fish. Iron deficiency → Anaemia (tiredness, pale skin). Sources: green leafy vegetables (keerai), dates, jaggery, meat. Iodine deficiency → Goitre (swelling in neck). Sources: iodised salt, seafood.

Amla (nellikkai/நெல்லிக்காய்) has 20 times the Vitamin C of an orange. It is a superfood widely available in Tamil Nadu. One amla a day can prevent scurvy.

Food preservation methods

Drying/sun-drying → removes water that microorganisms need to grow. Examples: vathal, dry fish, dry chillies, raisins, papad. Refrigeration/freezing → low temperature slows bacterial growth. Pickling → salt, oil, or vinegar creates an environment where bacteria cannot survive. Examples: mango pickle, lime pickle, onion pickle. Canning → food sealed in airtight cans and heated to kill bacteria. Adding sugar → high sugar concentration preserves fruits as jam, murabba, jelly. Vacuum packing → removes air (oxygen) from the packet.

Traditional Tamil preservation — vathal, pickles (oorugai), and fermented foods (idli batter, curd) — are scientific methods developed through centuries of observation, long before modern microbiology explained WHY they work.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Thinking refrigeration kills bacteria (it only slows them)

✓ Refrigeration does NOT kill bacteria — it only slows their growth. Food kept in the fridge will still spoil eventually. Freezing at −18°C stops bacterial growth almost completely but does not kill all bacteria. Only cooking at high temperatures kills bacteria reliably.

WATCH OUT

✗ Ignoring early signs of nutrient deficiency

✓ Frequent tiredness, pale skin = possible anaemia (iron deficiency). Bleeding gums while brushing = possible Vitamin C deficiency. Difficulty seeing at dusk = possible Vitamin A deficiency. These are your body's warning signals.

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