Science Class 9 - Why Do-We-Fall-Ill Notes
Comprehensive study notes for Class 9 - Why Do-We-Fall-Ill olympiad preparation
Why Do We Fall Ill?
In this chapter, you will learn why people fall ill, what causes diseases, how our body fights illness, and how we can stay healthy. By the end of this chapter, you will understand the difference between health and disease, types of diseases, and ways to prevent illness.
Key Concepts
- Health: A state of complete physical, mental, and social well-being.
- Disease: A condition when the body or mind does not function normally.
- Symptoms: Signs that show a person is ill (like fever, cough, pain).
- Causes: Reasons why we fall ill (like germs, poor nutrition, pollution).
What is Health?
Health is not just being free from disease. It means feeling good physically, mentally, and socially. Good health helps us study, play, and enjoy life.
What is Disease?
Disease is when something is wrong with our body or mind. It can be caused by germs, poor diet, lack of exercise, or pollution.
Causes of Diseases
- Infectious Diseases: Caused by germs like bacteria, viruses, fungi, and protozoa. Example: cold, malaria, tuberculosis.
- Non-Infectious Diseases: Not caused by germs. Example: diabetes, cancer, deficiency diseases.
- Poor Nutrition: Not eating healthy food can cause diseases like anemia and scurvy.
- Unhealthy Lifestyle: Lack of exercise, too much junk food, and stress can make us ill.
- Environmental Factors: Pollution, dirty water, and poor sanitation can cause illness.
How Does Our Body Fight Diseases?
- Our body has an immune system that fights germs.
- White blood cells help protect us from infections.
- Vaccines help our body fight certain diseases.
Prevention of Diseases
- Eat healthy and balanced food.
- Exercise regularly.
- Keep your surroundings clean.
- Wash hands before eating.
- Drink clean water.
- Get vaccinated.
Practice Questions
- What is the difference between health and disease?
- Name two infectious and two non-infectious diseases.
- How does poor nutrition affect our health?
- List three ways to prevent diseases.
- What is the role of vaccines?
Challenge Yourself
- Make a chart showing healthy habits and unhealthy habits.
- Find out about a disease caused by a virus and write how it spreads.
Did You Know?
- Louis Pasteur discovered that germs cause diseases and invented vaccines.
- Regular exercise boosts your immune system!
Glossary
- Immune System: The body’s defense against germs and diseases.
- Vaccine: A medicine that helps prevent certain diseases.
- Infectious: Can spread from one person to another.
- Non-Infectious: Cannot spread from one person to another.
Answers to Practice Questions
- Health means complete well-being; disease means something is wrong with the body or mind.
- Infectious: cold, malaria. Non-infectious: diabetes, cancer.
- It can cause deficiency diseases and make us weak.
- Eat healthy food, exercise, keep clean, get vaccinated.
- Vaccines help the body fight and prevent certain diseases.
Stay healthy by following good habits and learning how to prevent diseases!