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Tamil Nadu (TNBSE)Class 10 Science★ 3-6 marks in the TN SSLC Class 10 Science public exam through MCQs and short answers

Health and Diseases

Samacheer Kalvi (TN State Board) Class 10 Science — Biology Chapter 21, Health and Diseases. The meaning of health, communicable and non-communicable (lifestyle) diseases such as diabetes, obesity, cancer and heart disease, the harms of substance abuse, and disease prevention. Notes with classifications, common mistakes, practice and quick revision.

⏱ 18 min readEasy difficulty✓ Free · NCERT-aligned

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Study Guide

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

1Define health as per the WHO
2Differentiate communicable and non-communicable diseases
3Identify common lifestyle diseases
4Explain the harms of substance abuse
5List ways to prevent diseases

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Why this chapter matters

This chapter builds health awareness — distinguishing communicable from lifestyle diseases and explaining prevention and the harms of substance abuse. It offers easy recall marks in the TN SSLC exam and life-long practical value.

Before you start — revise these

A 5-minute refresher here will save you 30 minutes of confusion below.

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Chapter 16 — Plant and Animal Hormones

Insulin and diabetes.

Health and Diseases — Class 10 Science (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 10 Science, Biology — Chapter 21. Staying healthy and understanding the diseases that affect us.

1. About this chapter

This chapter explains health, the types of diseases (communicable and non-communicable / lifestyle), the dangers of substance abuse, and how diseases can be prevented.

2. What is health?

Health (WHO): a state of complete physical, mental and social well-being, not merely the absence of disease.

3. Types of diseases

Communicable (infectious): spread by pathogens — bacteria, viruses, etc. (e.g., tuberculosis, COVID-19).
Non-communicable (lifestyle) diseases: not spread person-to-person, often due to diet, inactivity or habits:
- Diabetes (high blood sugar, lack of insulin),
- Obesity (excess body fat),
- Cancer (uncontrolled cell growth),
- Cardiovascular disease (heart and blood vessels).

4. Substance abuse

Tobacco, alcohol and drugs harm the body and mind — causing cancer, liver and lung damage, and addiction. Avoiding them protects health.

5. Prevention

Balanced diet, exercise, hygiene, vaccination, clean water and sanitation, and avoiding substance abuse keep diseases away. Early diagnosis helps treatment.

6. Common mistakes

Mistake: Defining health as just "no disease." Fix: Health is complete physical, mental and social well-being.
Mistake: Calling diabetes a communicable disease. Fix: Diabetes is a non-communicable lifestyle disease.
Mistake: Thinking lifestyle diseases cannot be prevented. Fix: Diet, exercise and good habits greatly reduce the risk.

7. Practice (book-back style)

Define health as per the WHO.
Differentiate communicable and non-communicable diseases with examples.
Name two lifestyle diseases.
How does substance abuse affect health?
State three ways to prevent diseases.

8. Answer key

A state of complete physical, mental and social well-being, not merely the absence of disease.
Communicable spread by pathogens (e.g., TB); non-communicable are not spread person-to-person (e.g., diabetes).
Diabetes and obesity (also cancer, heart disease).
Tobacco, alcohol and drugs damage organs, cause cancer/addiction and harm mental health.
Balanced diet, regular exercise and good hygiene/vaccination (any three).

9. Quick revision

Biology Ch 21 · health and diseases.
Health = complete physical, mental and social well-being (WHO).
Communicable (pathogens, e.g. TB) vs non-communicable lifestyle (diabetes, obesity, cancer, heart disease).
Substance abuse (tobacco/alcohol/drugs) harms body and mind.
Prevent by diet, exercise, hygiene, vaccination and clean water.

Key formulas & results

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

Health (WHO)

physical + mental + social well-being

Not merely the absence of disease.

Disease types

communicable vs non-communicable

Pathogen-spread vs lifestyle.

Lifestyle diseases

diabetes, obesity, cancer, heart disease

Linked to diet and habits.

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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

✗ Defining health as just 'no disease'

✓ Health is complete physical, mental and social well-being.

WATCH OUT

✗ Calling diabetes a communicable disease

✓ Diabetes is a non-communicable lifestyle disease.

WATCH OUT

✗ Thinking lifestyle diseases cannot be prevented

✓ Diet, exercise and good habits greatly reduce the risk.

NCERT exercises

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Multiple choice questions

MCQs on health, disease types and prevention.

Questions

Short answer questions

Definitions, disease classification and substance abuse.

Questions

Awareness activity

Make a poster on a healthy lifestyle.

Questions

Practice problems

Work through this chapter's problems as a readiness check — reveal each solution, mark yourself honestly, and get your gap report at the end.

Readiness check

Are you exam-ready for Health and Diseases?

6 problems from this chapter. Try each one, reveal the worked solution, mark yourself honestly — get your gap report at the end.

6 questions~4 min worth ~6 marks in Tamil Nadu (TNBSE) exams

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Biology Chapter 21 of Samacheer Kalvi Class 10 Science.
•Health = complete physical, mental and social well-being (WHO).
•Communicable (pathogens, e.g. TB) vs non-communicable lifestyle diseases.
•Lifestyle diseases: diabetes, obesity, cancer, heart disease.
•Substance abuse (tobacco/alcohol/drugs) harms body and mind.
•Prevent by diet, exercise, hygiene, vaccination and clean water.

Tamil Nadu (TNBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 3-6 marks across MCQ and short-answer questions

Question type	Marks each	Typical count	What it tests
MCQ	1	1-2	Health, disease types
Short Answer	2-3	1-2	Classification and prevention
Awareness	2	0-1	Healthy-lifestyle activity

Prep strategy

Memorise the WHO definition of health
Classify diseases with examples
List prevention measures
Note the harms of substance abuse

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Personal health

Helps students make healthy diet and lifestyle choices.

Public health

Explains why hygiene, sanitation and vaccination matter.

Awareness

Builds resistance to tobacco, alcohol and drug abuse.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

Quote the WHO definition exactly

Use examples when classifying diseases

List concrete prevention steps

Keep substance-abuse points factual

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

STRETCH

Explain how a balanced diet prevents lifestyle diseases.

STRETCH

Compare the spread of a communicable disease with a non-communicable one.

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

TN SSLC Class 10 Public ExamHigh

Foundation / NTSE BiologyMedium

School unit testsHigh

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Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

Sedentary habits, unhealthy diets, stress and substance use raise the risk of conditions like diabetes, obesity and heart disease.

A vaccine trains the immune system to recognise a pathogen in advance, so the body can fight it off quickly if exposed later.

Practice more, ask doubts, find a tutor

Tamil Nadu (TNBSE) Class 10 mock tests

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