CBSE Class 9 Science Chapter 13: Why Do We Fall Ill - NCERT Solutions

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NCERT Solutions PDF Class 9 PDF

This chapter delves into the fundamental concepts of health and disease, crucial for Class 9 Science students following the CBSE curriculum. The NCERT Solutions for 'Why Do We Fall Ill' explain the conditions necessary for maintaining good health, distinguishing between being healthy and being disease-free. It further explores the various causes of diseases, the difference between acute and chronic illnesses, and the importance of seeking medical attention. The solutions also discuss the long-term health implications of different ailments and the significance of prevention and treatment. These solutions are designed to provide clear, step-by-step explanations, aiding students in understanding complex topics and preparing effectively for their examinations.

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BoardCBSE
ClassClass 9
SubjectScience
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 13

Chapter summary

Chapter 13, 'Why Do We Fall Ill,' focuses on understanding the concepts of health and disease. The NCERT Solutions cover the essential conditions for good health, the difference between being healthy and disease-free, and the various causes of diseases. It differentiates between acute and chronic diseases and highlights the importance of symptoms in diagnosing illness and the potential long-term effects on health. The solutions emphasize prevention and treatment strategies, making them a valuable resource for students.

Learning outcomes

  • Understand the definition and conditions for good health.
  • Differentiate between being healthy and being free from disease.
  • Identify the causes and types of diseases (acute vs. chronic).
  • Recognize symptoms that indicate illness and the need for medical consultation.
  • Evaluate the long-term health consequences of various diseases.

Topics covered

Paper topics

  • Definition of Health
  • Conditions for Good Health
  • Being Healthy vs. Being Disease-Free
  • Causes of Diseases
  • Types of Diseases (Acute and Chronic)
  • Symptoms of Diseases
  • Importance of Medical Consultation
  • Long-term Effects of Diseases
  • Prevention of Diseases
  • Personal and Public Hygiene

Important topics

  • Conditions for Good Health
  • Difference between Acute and Chronic Diseases
  • Symptoms and their significance
  • Long-term health effects
  • Prevention and Hygiene

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Questions and Solutions

Question 1

State any two conditions essential for good health.
Solution: Health is defined as a state where an individual is well physically, mentally, and socially, enabling them to function effectively. Therefore, two essential conditions for maintaining good health are:
  1. The individual should be free from any diseases or ailments.
  2. There should be social equality and harmony, as these factors significantly contribute to an individual's mental and social well-being.

Question 2

State any two conditions essential for being free of disease.
Solution: To remain free from disease, the following conditions are essential:
  1. It is crucial to avoid exposure to the specific causes or agents that lead to discomfort or disease. This necessitates maintaining personal hygiene and ensuring a clean physical environment.
  2. Consuming proper and sufficient food is vital for the optimal functioning of all cells and tissues within the body, supporting overall health and disease resistance.

Question 1

List any three symptoms that would make you think you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Explain why or why not.
Solution: Common symptoms that indicate sickness and suggest a visit to the doctor include:
  1. Headache
  2. Cough
  3. Loose motion
Yes, even if only one of these symptoms were present, I would still consider going to the doctor. Reason: A single symptom can be an early indicator of an underlying disease. Delaying medical consultation might allow the condition to progress, potentially leading to more serious health issues. For instance, a persistent headache could be a sign of a condition like meningitis, which requires prompt medical attention.

Question 2

In which of the following cases do you think the long-term effects on your health are likely to be most unpleasant? If you get jaundice, if you get lice, or if you get acne? Why?
Solution: Among the options provided, jaundice is likely to have the most unpleasant long-term effects on health. This is because jaundice is often a chronic disease that affects the liver and can take a considerable amount of time to be fully cured. Its impact is systemic, affecting the whole body and requiring a prolonged period to regain complete health, unlike lice or acne which are typically less severe and have shorter-term consequences.

Common mistakes

  • Confusing 'being healthy' with 'being disease-free'.
  • Underestimating the significance of single symptoms.
  • Not considering the long-term effects of chronic diseases.
  • Overlooking the importance of personal and public hygiene.

Revision tips

  • Focus on the definitions of health and disease and the conditions required for each.
  • Understand the difference between acute and chronic diseases with examples.
  • Pay attention to the reasons why symptoms indicate sickness and the need for a doctor.
  • Review the long-term implications of diseases like jaundice.
  • Emphasize the role of hygiene and proper nutrition in preventing illness.

Practice MCQs

Q1. Which of the following is essential for good health?

Q2. What is a key condition for being free of disease?

Q3. Which symptom might indicate a serious illness requiring a doctor's visit?

Q4. Why is jaundice considered to have more unpleasant long-term effects than lice or acne?

Q5. What is the difference between acute and chronic diseases?

Frequently asked questions

What are the essential conditions for good health according to NCERT Class 9 Science?

For good health, two essential conditions are being free from disease and maintaining a state of physical, mental, and social well-being, which includes social equality and harmony.

What are the key requirements to be free of disease?

To be free of disease, one must stay away from the specific causes of illness and maintain both personal and public cleanliness. Adequate and proper food is also necessary for the body's cells and tissues to function correctly.

Why is it important to see a doctor even with a single symptom of illness?

A single symptom can be an early sign of a disease. Delaying medical attention might allow the illness to worsen, potentially leading to serious health complications, as exemplified by a headache possibly indicating meningitis.

Which disease among jaundice, lice, and acne is likely to have the most unpleasant long-term health effects?

Jaundice is likely to have the most unpleasant long-term effects because it is a chronic disease that affects the entire body and requires a significant amount of time for recovery.

What is the main focus of Chapter 13, 'Why Do We Fall Ill'?

This chapter focuses on understanding the fundamental concepts of health and disease, including their causes, types, symptoms, and the importance of prevention and treatment for maintaining well-being.

Important links

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