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

Last updated date: 27th Jun 2024
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NCERT Solutions for Class 9 Science Chapter 13 - Free PDF Download

The Science syllabus of Class 9 CBSE is quite vast for students who have just entered the Secondary level. The chapters included in the science book are remotely related to what you have studied before. You will have to dig a little deeper into the concepts by studying these chapters and learn how to answer various questions. One of the prime chapters related to Biology is Why Do We Fall Ill Class 9. You will find excellent information related to our health, diseases and pathogens causing them. It will also tell us how these diseases can be managed and treated. There are specific questions in the exercises in this chapter that will test your understanding. Register Online for Class 9 Science tuition on to score more marks in your examination. Vedantu is a platform that provides free NCERT Solutions and other study materials for students. Maths Students who are looking for better solutions. They can download Class 9 Maths NCERT Solutions to help you to revise the complete syllabus and score more marks in your examinations.


NCERT Solutions For Class 9


Class 9 Science

Chapter Name:

Chapter 13 - Why Do We Fall Ill

Content Type:

Text, Videos, Images and PDF Format

Academic Year:



English and Hindi

Available Materials:

Chapter Wise

Other Materials

  • Important Questions

  • Revision Notes

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NCERT Solutions for Class 9 Science Chapter 13 - Why Do We Fall Ill
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Access NCERT Solutions for Biology Chapter 13 - Why Do We Fall Ill

1. State Any Two Conditions Essential for Good Health. 

Ans: Two conditions essential for good health are: 

  • Availability of better health facilities to deal with problems. 

  • Basic necessary conditions to stop diseases must be present.  


2. State Any Two Conditions Essential for Being Free of Disease. 

Ans: The two conditions essential for being free of diseases are: 

  • Personal hygiene and cleanliness should be maintained. 

  • Intake of a balanced diet and nutritious food. 


3. List Any Three Reasons Why You Would Think That You Are Sick and Ought to See a Doctor. If Only One of These Symptoms Were Present, Would You Still Go to the Doctor? Why or Why Not? 

Ans: The presence of symptoms such as headache, stomach pain, nausea, vomiting, fever, etc., make us feel that we are sick and must visit a doctor. It will be difficult for us to predict the kind of disease and end up visiting the doctor so that the disease can be treated with proper medication. However, we usually do not visit a doctor, if only one of these symptoms is present. This is because such symptoms do not have much effect on our general health and ability to work.  So, if a person is experiencing these symptoms quite regularly, then he/she needs to visit a  doctor for proper treatment because that may be a symptom of severe disease. 


4. In Which of the Following Cases Do You Think the Long-Term Effects on Your Health are Likely to Be Most Unpleasant? 

(a) If you get jaundice, 

(b) If you get lice, 

(c) If you get acne. 


Ans: If we get jaundice it will be the most unpleasant because it is a chronic disease and can cause long-term effects on our health. Lice and acne can be cured by using medicated shampoo and proper cleanliness respectively. 


5. Why are We Normally Advised to Take Bland and Nourishing Food When We are Sick? 

Ans: We are normally advised to take bland and nourishing food when we are sick because when we are sick our body will be weak, so by consuming bland and nourishing food we can get the nutrients and energy quickly to fight the disease-causing agents. Oil and spices will be difficult to digest because our metabolic system is weak. 


6. What are the Different Means by Which Infectious Diseases are Spread?

Ans: The different means by which infectious diseases are spread are as follows:

Diseases can be spread through various means such as air, water, sexual contact, blood and vector. 

  • Through Air - This occurs through the little droplets thrown out by an infected person during sneezing or coughing. For example, tuberculosis, pneumonia, etc. spread through the air. 

  • Through Water - This occurs if the excreta of an infected person who is suffering from an infectious gut disease, such as cholera, get mixed with the drinking water used by people living nearby. 

  • Through Physical Contact - Sexual act is one of the closest physical contact two people can have with each other. 

  • Blood Transfusion - Certain diseases such as AIDS can spread via the blood to blood contact during a blood transfusion or pregnancy. 

  • Through Vectors - Diseases can spread through vectors. For example, mosquitoes spread malaria. 


7. What Precautions Can You Take in Your School to Reduce the Incidence of Infectious Diseases? 

Ans: To reduce the incidence of infectious diseases in our school the following precautions must be taken:

  • Cover mouth or nose while sneezing. 

  • To avoid the breeding of mosquitoes we will make sure that water is not stagnant too. 

  • Drinking filtered or purified water to avoid the spread of water-borne diseases. 


8. What is Immunization? 

Ans: Immunization is a process of protecting the body from communicable diseases by administration of the agent that mimics the microbe.  


9. What are the Immunization Programmes Available at the Nearest Health Center in Your Locality?  Which of These Diseases Are the Major Health Problems in Your Area?

Ans: The immunization programmes available at the nearest health center in my locality are DPT, polio vaccine, Hepatitis B, MMR, jaundice,  typhoid, etc.  The diseases that are the major health problems in a  particular area depends upon the hygiene and cleanliness maintained in that area.


10. How Many Times Did You Fall Ill in the Last Year? What Were the Illnesses? 

(a) Think of one change you could make in your habits in order to avoid any of /most of the above illnesses. 

(b) Think of one change you would wish for in your surroundings in order to avoid any of/most of the above illnesses. 

Ans: The number of times an individual falls ill in a year depends on the immunity system of that individual. Few might fall ill several times in a year whereas others do not fall ill at all.  Illness may be fever, cold and cough etc. 

  • In order to avoid any of /most of the above illnesses, I will develop the habit of eating fresh and healthy food. 

  • Drinking boiled water. 


11. A Doctor/Nurse/Health Worker is Exposed to More Sick People Than Others in the Community. Find Out How She/He Avoids Getting Sick Herself/Himself. 

Ans: A doctor/nurse/health worker is exposed to more sick people than others in the community. Following are the steps were taken by them to avoid getting sick:

  • They should keep themselves covered while moving around an infected place. 

  • When in contact with an infected person they should wear a mask and gloves. 

  • Eating healthy and nutritious food. 

  • Ensuring proper cleanliness and personal hygiene. 


12. Conduct a Survey in Your Neighborhood to Find Out What the Three Most Common Diseases Are. Suggest Three Steps That Could Be Taken by Your Local Authorities to Bring Down the Incidence of These Diseases. 

Ans: After conducting a survey in our neighborhood the three most common diseases found are Dengue, Typhoid, Jaundice. etc. The steps to be taken to bring down the incidence of these diseases are:

  • Proper disposal of garbage so that a clean environment should be provided.

  • Proper maintenance of open sewage systems and canals. 

  • The supply of safe drinking water must be ensured. 

  • The breeding of mosquitoes must be prevented.


13. A Baby is Not Able to Tell Her/His Caretakers That She/He is Sick. What Would Help Us to Find Out 

(a) That the baby is sick? 

(b) What is the sickness? 

Ans: Following symptoms will help a caretaker to know regarding the illness/sickness of a baby:

  • By the behavioral changes of the baby sickness can be determined. 

  • Sickness can be symptoms or indications which include vomiting, fever, loose motion,  paleness in the body, etc. 


14. Under Which of the Following Conditions is a Person Most Likely to Fall Sick? 

(a) When she is recovering from malaria. 

(b) When she has recovered from malaria and is taking care of someone suffering from chickenpox. 

(c) When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chickenpox. Why? 

Ans: Under the condition ‘C’ a person is more likely to fall sick because she is already fasting during recovery, and her immune system is so weak that it is not able to protect its own body from any foreign infection. If that person is taking care of someone suffering from chickenpox, then she has more chances of getting infected from the chickenpox virus and will get sick again with this disease. 


15. Under Which of the Following Conditions are You Most Likely to Fall Sick?

(a) When you are taking examinations. 

(b) When you have traveled by bus and train for two days. 

(c) When your friend is suffering from measles. 


Ans: A person is more likely to fall sick under the situation “C” because measles is a highly communicable disease and can easily spread through the air. So, any of your friends are suffering from measles, you have to stay away from him otherwise you might easily get infected with the disease.


NCERT Solutions for Class 9 Science Chapter 13 - Why Do We Fall ill

You can opt for Chapter 13 - Why do We Fall ill NCERT Solutions for Class 9 Science PDF for Upcoming Exams and also You can Find the Solutions of All the Math Chapters below.


NCERT Solutions for Class 9 Science


Along with this, students can also view additional study materials provided by Vedantu, for Class 9


Important Topics

The Topics and Sub Topics in Class 9 Science Chapter 13 Why Do We Fall Ill contain as follows:

  1. Health and its failure

    1. The significance of ‘Health’

    2. Personal and community issues both matter for health

    3. The distinction between healthy and disease-free

  2. Diseases and its causes

    1. What do diseases look like?

    2. Acute and chronic diseases

    3. Chronic diseases and poor health

    4. Causes of diseases

    5. Infectious and non-infectious diseases

  3. Infectious diseases

    1. Infectious agents

    2. Means of spread

    3. Organ-specific and tissue-specific manifestations

    4. Principles of treatment

    5. Principles of prevention

Important Points

  • There are two types of reasons for disease: direct and contributing factors. The organisms that enter our bodies and create disease are the immediate cause. Viruses, protozoa, and bacteria are examples. Secondary causes: These are the factors that cause these creatures to enter our bodies.

  • Sickness is defined as a state in which the body is not at ease, or comfortable.

  • The functioning or appearance of one or more body systems alters when there is a disease.

  • The condition is characterized as acute or chronic depending on how long it lasts.

  • Acute disease is defined as a condition that lasts for a short amount of time, such as a headache or a common cold.

  • Chronic diseases are diseases that endure for a long time, such as elephantiasis, tuberculosis, and others.

  • The following are some of the essential requirements for optimal health:

  • A diet that is well-balanced and nutritious.

  • Personal hygiene is really important.

  • The setting and surroundings are both clean.

  • There is no pollution in the area, thus the air is clean.

  • Exercise on a regular basis.

  • Restful sleep is essential.

  • Good living conditions and financial standing.

Why Do We Fall Ill: Ch 13 Science Class 9

Refer to the Why Do We Fall Ill Class 9 NCERT Solutions for learning how to answer such questions and score better. You have to be very specific regarding answering such conceptual questions. Study the chapter and keep the NCERT Solutions for Class 9 Science Chapter 13 for reference. You can download it on your computer in PDF format and use it whenever you want.

This chapter will take you to the world of microorganisms and diseases that cause havoc in the human population. You will come to know why the diseases occur and how they can be managed by using the specific treatments developed over the years. When you follow the class sessions, you will find the definition and significance of health and different kinds of diseases humans suffer from. By referring to the Why Do We Fall Ill Class 9 PDF file, you will discover how to answer the questions included in the exercises. Understand the difference between acute and chronic diseases properly and create your answers for the questions.

As you know there are many new chapters that you have never encountered before, you will have to pay more attention to the class and follow a guide to learn how to approach the conceptual question in the exercises. The Why Do We Fall Ill Class 9 solutions have been formed by the best teachers of Vedantu. The teachers follow the basic rules of CBSE to answer these conceptual questions related to Biology. By following specific ways, you will be able to answer precisely and score more in the exams. Apart from the school lectures and tuitions, you will need the assistance of Chapter 13 Science Class 9 NCERT Solutions to make your preparation easier and better. You will not have to study repeatedly to remember the concepts when you follow the simplest answering formats mentioned in the solution.


Save Time While Preparing Why Do We Fall Ill Class 9 NCERT PDF

As mentioned earlier, the Class 9 students will have to be very productive to handle so many different subjects with a huge syllabus. They have to segregate their day to attend school, go for tuitions, and find time to practice what they have studied. Learning new concepts can be very tough when the students do not get ample time to practice on their own. This is where the solutions for the chapters can be very helpful to develop time-saving skills. Using NCERT Solutions Class 9 Science Chapter 13 will help you stay a step ahead of the class. You can easily prepare for the upcoming exams and manage time by using the solutions to all the problems in this chapter.

There are four exercises in Chapter 13 Science Class 9 covering all the units of concepts related to diseases, communication, infection, cure, treatment, etc. There are so many new things to learn in this chapter. It can be an overload for students handling other subjects at the same time. The availability of Ch 13 Science Class 9 NCERT Solutions makes it easier to complete such crucial chapters one by one within a short period. You will have to study the chapter as you will need to create a base related to diseases, pathogens, and treatments for the future. If you choose the Science stream at the Higher Secondary level, you will need this foundation of knowledge to strengthen your subject skills. Following the tips and tricks of NCERT Solutions for Class 9 Science Chapter Why Do We Fall Ill will help you do that.


Why Choose Vedantu’s NCERT Solutions for Class 9 Science Chapter 13?

Quality answers and impeccable use of CBSE rules are what you will find in NCERT Solutions for Class 9 Science Why Do We Fall Ill, prepared by the top teachers of Vedantu. Students prefer seeking solutions related to different chapters in the Class 9 Science book because of the organized presentation of the answers providing ample knowledge to students. Following these NCERT Solutions of Class 9 Science Chapter 13 will help you score higher than before as your preparation will become better and well-structured.

FAQs on NCERT Solutions for Class 9 Science Chapter 13 - Why Do We Fall Ill

1. Why do you Need Class 9 Biology Chapter 13 NCERT Solutions?

The Biology questions focus on the concepts mentioned in the chapters. Your answer has to be precise. Hence, following NCERT Solutions Class 9 Science Chapter Why Do We Fall Ill at the initial level will help you understand the format for answering. You will be able to answer all questions without wasting time and score higher.

2. How can I Score Well by Using NCERT Solutions Class 9 Science Why Do We Fall Ill?

The reason for using the NCERT Biology solution is to gain proper knowledge regarding the new concepts of the chapter and how to use them to answer by following the CBSE guidelines. Every answer format in the solutions provided by Vedantu follows the latest CBSE rules.

3. What is the Way to Save Time While Answering Class 9 Biology Chapter 13 Questions in an Exam?

When you follow NCERT Solutions for Class 9 Biology Chapter Why Do We Fall Ill, you will find how precise the answers are. Focus on using the right concept and stay within the specified word limit to save time.

4. Where can I get the NCERT Solution for Class 9 Science?

Vedantu provides quality answers while strictly adhering to the CBSE pattern and guidelines. It is the best place for chapter-wise NCERT Solutions of Class 9 Science. The study material and solutions provided here are prepared by expert teachers of Vedantu. The Solution PDFs can be downloaded free of cost from the vedantu website. All the study material is also available on the vedantu app. Follow these NCERT Solutions to score higher than before and make your exam preparation more well-structured. 

5. What are the topics and subtopics present in Chapter 13 of NCERT Solutions for Class 9 Science?

Vedantu's NCERT Solutions for Class 9 Science, Chapter 13, 'Why Do We Fall Ill' covers all the major topics from an examination point of view. There are solutions to exercises covering all the units and basic concepts related to Health, The Difference Between Being Healthy and Disease-free, Disease and Its Causes, Types Of Diseases- Infectious and Non-infectious Diseases, Communication Of Diseases, Treatment, Microorganisms, Antibiotics etc.

6. What is Immunisation?

One of the specific ways to prevent the spread of infectious diseases is through immunisation. Immunisation is a process through which the immunized person develops antibodies that provide resistance against particular diseases. This resistance is developed through vaccination. A vaccine is a dose of specialized medication that helps fight certain diseases by stimulating the immune system of the vaccinated person.

7. What do you mean by symptoms of the disease?

The symptom of a disease refers to the physical or mental problem experienced by a person that may indicate a disease or a health condition. In simple words, a symptom is an indicator of the disease. They cannot be seen and they do not show up on medical tests. For instance, some symptoms of Malaria are fever, nausea and muscle pain. Similarly, symptoms of Typhoid are fever, loss of appetite and abdominal pain.

8. Why do you fall ill according to the Class 9 Science Syllabus?

Generally, we fall ill due to either immediate or contributory causes of illness. The organisms (pathogens) entering our body and causing the disease are called the immediate cause. For example, microorganisms like viruses, bacteria, protozoa etc. are the immediate causes of illness. Contributory causes are the secondary factors that lead these pathogens or organisms to enter our bodies. For instance, dirty water, contaminated food, improper nourishment, poor standard of living, etc. are the contributory causes of illness.