NCERT Solutions for Class 9 Science Chapter 13 - Free PDF Download
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NCERT Solutions for Class 9 Science Chapter 13 - Why Do We Fall ill
Chapter 13 Class 9 Science is a part of the unit Organisation in the Living World. It asks a vital question in the name of the chapter, Why do We Fall Ill? This Chapter 13 Science Class 9 keeps the learners informed about the notions of health and the formation of diseases within the human body. A wide range of topics are discussed throughout the chapter. NCERT Solutions for Class 9 Science Chapter 13 helps the student answer the textual questions skilfully.
The Ch 13 Science Class 9 is inclusive of various topics ranging from the significance of health, factors affecting a health condition, differentiation between staying healthy and disease-free and so on and so forth. The very important aspect of health is to observe well being from all points of views such as physical, mental, social, etc. This chapter highlights that notion too. We present you with a brief glance at what you will come across while studying Class 9 Science Chapter 13.
A list of factors or conditions is essential for maintaining good health. Proper health facilities and their easy availability determine whether an individual will be able to avail health or not. Public cleanliness and the environment in where an individual dwells must be clean and sanitised for ensuring better health to the people residing in the society. In addition to that, the individuals of a community must be ensured the availability and affordability of food. The affordability will come only when economic earning is secured. Thus a stable economic condition also contributes to the development of good health in individuals.
Class 9 Chapter 13 Science also tells you that you need a good social environment as well for maintaining good health. If you are dwelling in a disturbing situation where you are always stressed and undergo mental pressure, your physical health will not be able to keep up. Thus, s per the definition of World Health Organisation (1948) “Health is a state of complete physical, mental and social well-being and not merely an absence of disease”.
This gives rise to the next question that what it takes to be free from diseases. Disease is necessarily an abnormality in our body due to the intrusion of foreign elements or internal dysfunctionality. Thus living in a hygienic condition with complete sanitation, having a balanced diet etc contribute to the disease-free condition. You can identify the presence of disease in your body through the symptoms your body shows, or when the functions of a particular body part is hampered. Doctors rely on clinical signs or lab results for coming to a conclusion about the presence of disease.
You must keep in mind that while being healthy deals with the full potential of an individual, being disease-free is just the absence of disease condition from the body. You may possess poor health even if you do not have any signs and symptoms of diseases. While health is also concerned about the social and community conditions, disease is very much individual-centric.
Disease can again be of two broad categories named acute disease and chronic disease. In the former, the span of disease condition is short and caused randomly. But the general health remains largely unchanged. In chronic disease, you get to suffer for a long period of time and the disease develops over a particular span of time. The general health is largely affected. Dysentery, cold and cough etc are acute diseases while CVD, TB are examples of chronic disease.
Next in the Science Class 9 Chapter 13 you get to learn how chronic disease affects our health. As chronic diseases are spanned over a long period of time our overall health is affected adversely. Longer periods of chronic disease may deteriorate the growth of children if they get affected in an early stage. In the case of adults, increased stress is a common feature imposed by chronic disease. You always feel tired as the disease takes up a lot of energy and also hampers your digestive system. Fluctuations in weight can also occur. Chronic diseases possess the ability to hamper your daily activities. In addition, you may lose your readiness to learn new lessons. Thus, unlike acute disease, you are affected long term by chronic disease effects.
While reading the Ch 13 Science Class 9 you will come across another question which must have been bothering you for a long time. What causes disease in us? As we mentioned earlier, it might be some external or internal reasons contributing to the development of disease in our body. Consumption of an unhealthy diet or intrusion of disease-causing germs such as fungi, viruses, bacteria of all kinds can cause disease. Some uncontrollable causes like pollution in our surrounding environment can cause disease in us. Unhealthy lifestyle led by us often sum up to disease condition in our body. These are also referred to as contributory causes of diseases.
Apart from these external factors, some internal situations like hormonal imbalance and allergic reaction also cause diseases to occur. Sometimes we possess some genetic disorder in us due to which we get a certain disease runs in our family. Diabetes and obesity are such kinds of diseases. Sometimes one or more of our body organs stop working or their functionalities can get hampered with. Such malfunction leads to disease conditions.
CBSE Class 9 Science Chapter 13 then classifies the causes of diseases in two simple yet broad categories. One of them is immediate causes referring to the actual contributory factors of a particular disease. They can be infectious and non-infectious both. The infectious causes are generally extrinsic or external in nature. Their activity leads to infectious disease development. If not controlled in the earlier stages, a whole community can be affected by such disease as it can be transferred from one affected person to another.
The non-infectious causes are the internal disease-causing factors leading to the development of non-communicable diseases and there is no risk of the whole community getting affected. These diseases cannot be transferred from one individual to others and thus do not involve the risk of getting widespread. This is one of the biggest and most evident differences between communicable and non-communicable diseases.
Pathogens from extrinsic factors are mainly responsible for the development of infectious diseases. But the internal factors are devoid of pathogens and so the non-infectious diseases are not caused by them. Transmission of the infection can occur through various medium. Direct contact with the infected person or sputum from the affected individual released into the air through coughing or sneezing can cause the transmission. Air, water, vectors act as the medium. Transmission of non-infectious diseases cannot be possible through these media. But it can be transferred from one generation to another as a hereditary trait. From parents to the child a non-communicable disease can be passed on.
Maintaining the hygiene of a community can reduce the possibilities of the spread of infectious diseases. But this measure does not come in handy for non-infectious diseases as they do not spread through a community due to transmission from one another. Chickenpox, TB, influenza etc can be termed as communicable or infectious diseases while hypertension, cancer, diabetes can be called non-infectious or non-communicable diseases.
Now how these infectious diseases are formed? You are already informed about the causative agents of various diseases. Virus, Bacteria, worms, protozoa, and fungi can act as infectious agents. Some common viruses are coronaviruses (common cold), influenza virus (influenza), dengue virus (dengue, borne by a mosquito), Human Immunodeficiency Virus/ HIV (AIDS) etc.
Some common bacteria causing various diseases in us are Salmonella (Typhoid fever), Vibrio cholerae (Cholera), Mycobacterium tuberculosis (TB) etc. Fungi are mainly responsible for skin diseases, rashes and irritations, fungal infection in the lungs etc. Plasmodium vivax (Malaria) and Leishmania (Kala-azar) are some protozoa which cause the diseases. Round work, tapeworm etc are worms which can deteriorate the complete internal organs and cause diseases like Elephantiasis.
Now among these causative agents of the diseases, not all of them share the same characteristics. While viruses settle inside the body, the bacteria do not live inside the human body. Fungi, along with the viruses and the bacteria can multiply very fast once they attach the humans. But the worms cannot multiply that much faster. As they differ in actions and characteristics it is important for us to know them. Only then the output of their actions can be treated accordingly.
In this regard, you get introduced to penicillin in Class 9 Science Chapter 13. Penicillin is an antibiotic which can act extensively against bacteria and prevent their cell wall from growing. This cell wall of bacteria actually protects it. Penicillin, or any antibiotic for that matter, act in the same way. This way the bacteria die. Thus penicillin holds an important position in controlling disease causing bacteria.
Moving further in the chapter, you get more familiar with certain types of diseases. You were already informed that various types of medium are used by the causative agents to get transmitted in the human body. In this respect, the diseases are brought under the headings of airborne, foodborne, waterborne, and so on and so forth. Now we will give you a brief glance at these diseases, their causative agents, and examples.
Common cold, tuberculosis etc are some examples of airborne diseases which are caused by germs, bacteria or virus blowing into the air. Typhoid, Food poisoning etc are examples of some food borne diseases which come from the germs and bacteria present in the food itself. As for waterborne diseases, cholera and amoebiasis are two such examples which are caused due to drinking contaminated water. CVD or cardiovascular diseases, diabetes etc are examples of lifestyle diseases. Faulty habits, unhealthy lifestyle, consumption of high carbohydrate and fat rich foods, leading a stressful life etc are causes of developing these diseases.
Diseases can be vector borne also. In these diseases an animal, or an insect act as an intermediate between the causative agent and the human beings. These intermediates are called vectors. The vectors carry the germs or the infectious agents which are then transmitted to a healthy person. Malaria, Dengue fever etc are excellent examples of vector borne diseases where mosquito acts as the vector.
Diseases can be transmitted sexually also. Unprotected sex and sexual contact can cause the transfer of certain diseases from one person to other. AIDS, Syphilis are some such diseases commonly termed as sexually transmitted disease or STD.
Now that you know that the disease causing agents are living within your body, you may ask where. The Ch 13 Science Class 9 gives you the answer to that. The germs or microbes, in general, can get attached to various tissues and cells of various organs inside your body. The place where they will settle is usually determined by the pathway they choose to enter into your body. If a germ enters through your nostrils, it is likely to affect your respiratory system. Which body part the microbes have attacked can also be understood from the exhibition of symptoms in that particular body part. Like, a runny nose or cough will tell you your respiratory system has been affected.
Opting for NCERT Solutions for Class 9 Science Chapter 13 Why Do We Fall Ill further informs you about the automatic immune system of the body which is again exhibited through inflammation. Our body has immune systems ready in it to fight off foreign elements, especially the disease causing ones. Now, the process by which these fighter cells are recruited to battle the infectious agents is known as inflammation. Inflammation is characterised by certain effects on our body. Sometimes you get a fever or swelling due to the act of inflammation.
Science Chapter 13 Class 9 Question Answer moves on to answer your another query as to what exactly the immune system is. Tissues, cells, organs come up together and form a huge network so that it can protect our body from the attacks of diseases or disease causing agents. The defence system of our body- that’s what it is. This system is always on the lookout for disease causing germs so that it can readily destroy them. This act of destruction is facilitated by the action of white blood cells or WBC. These cells circulate throughout the body through blood and destroy germs capable of causing disease in our body. It is these cells which actually provide immunity to the body.
Immunity can be defined as the capability of your body to resist a disease condition and continue with good health, disease-free condition. In this situation, two more elements, antigen and antibody get involved. The foreign elements, including the germs or any other microbes, are termed as antigens. When these antigens are recognised by the immune system, it releases the antibodies. These antibodies actually destroy the antigens by locking their growth and action. Other cells also partake in this process of destruction.
Now how can we prevent all these? Why Do We Fall Ill Class 9 NCERT Solutions help you solve your this query too? Both treatment and prevention are important for dealing with disease conditions. There are two ways to treat an infectious disease once it has infected your body. You can either kill the infectious disease-causing agent or you may reduce their ill effects by controlling the symptoms. For killing them, you need to incorporate medicines such as antibiotics or antiviral ones. But there are certain limitations of treating the infection. You may not be able to recover your body functions quickly while affecting your daily activities. As for prevention of the disease, you need to restrict yourself so that you are not exposed to the agents. Also, you need to strengthen the immune system.
Now when you come towards the end of the chapter, you are presented with a unique piece of information stating that the antibiotics are not effective in viral diseases. If you think of it in this way, it certainly appears justified. This is the little tricks NCERT Solutions for Class 9 Science Chapter 13 Why Do We Fall Ill has in store for you to make the complete learning experience more interesting and unique. Actually, antibiotics block the biochemical pathway which the bacteria use for flourishing in the human body. This way, the growth of bacteria is stopped or arrested. Sometimes antibiotics act as bacteriostatic agents and destroy the metabolism of the bacteria which eventually kills them.
But the viruses do not use the same pathway as the bacteria. Thus even if the antibiotics block the pathway, the viruses remain unharmed. Instead, the viruses use the cellular system of the host to continue with its metabolic processes and produce protein. To keep viral infection at bay, you need to have vaccination done against the particular viral diseases. This way you may avoid the attack.
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The NCERT Solutions for Class 9 Science Chapter 13 Why Do We Fall Ill by Vedantu is your one-stop solution for all the textual questions and answers. It not only includes the questions at the end of the chapter but also in text questions. All of them are answered accurately. The chapter is covered thoroughly in these NCERT solutions leaving you no scope for being left out on any information.
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The answers are written in simple language. No heavy and complicated scientific terms have been used. Such quality of the content helps you memorise the answers easily. Easier you find the answers to read, the quicker you will recall them during your exams. Result? High scores in your paper. The solutions by Vedantu adhere to the NCERT guidelines. Thus it is easier to create a great impact on the examiners. This will definitely reflect on your paper.
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