NEET Foundation Physics Chapter 4 Why Do We Fall Ill Long Answer Questions

Chapter 4 Why Do We Fall Ill Long Answer Type Question And Answers

Question 1. What are the diseases? Discuss the various factors which trigger disease.


Disease is defined as an abnormal condition that disturbs or modifies the performance of vital functions of the body. Disease may result as a response to either of the following factors.

  • Environmental factors: Industrial hazards, natural calamities and malnutrition.
  • Infective agents: Worms, protozoan, bacteria, fungi and virus.
  • Inherent defect of the organism: Genetic anomalies.

Why Do We Fall Ill

Question 2. There are various modes of spreading the infection from an infected person to a healthy person. Discuss the direct and indirect methods of transmission. How sexually transmitted diseases are spread?

There are various modes of spreading the infection from an infected person to a healthy person.

  • Indirect transmission: It occurs when there is no direct human to human contact. The spreading of diseases is through air, water, vectors and contaminated surfaces and objects.
  • Direct transmission: It occurs when there is a physical contact between the infected and susceptible person. It includes sexual contact, animal bites and contact with soil.

Syphilis, gonorrhoea and AIDS are some examples of sexually transmitted diseases. The pathogens for these diseases are transmitted through sexual intercourse between the two partners.

However, such sexually transmitted diseases are not spread by casual physical contact such as handshakes or hugs or sports, like wrestling or by any of the other ways in which we touch each other socially.

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Question 3. Discuss the principle of prevention of diseases and discuss how we can prevent the occurrence of diseases.

The principle of prevention of diseases:

  • Firstly, when someone is suffering from a disease, their body becomes weak and it takes time to recover completely.
  • Secondly, the treatment takes time which means that someone suffering from a disease will have confined to bed till its convalescence.
  • Thirdly, the individual suffering from an infectious disease may acts as a potent source to spread infection to other people or to the community.

There are various ways by which we can prevent the occurrence of disease and it is as follows.

  • For airborne infection, we can prevent exposure by providing living conditions that are not overcrowded.
  • For waterborne infection, we can prevent exposure by procuring clean drinking water.
  • For prevention from vector-borne infections, clean environment is necessary. For example: Mosquito breeding can be stopped by ensuring cleanliness of water.

Question 4. Describe the symptoms and prevention of Hepatitis A and B.

Symptoms and prevention of Hepatitis A and B:

Hepatitis A is an acute infectious disease of liver that affects both children and adult. Symptoms are high body temperature, headache, fatigue, joint paints, vomiting, nausea, loss of appetite, dark yellow skin and urine due to the presence of pigment named bilirubin and light coloured stool within 3–10 days of infection.


  • Use of chlorinated, boiled or mineral water.
  • Hands should be washed after cleaning the bed and vessels of the patients.
  • Proper vaccination.

Hepatitis B: Hepatitis B is commonly known as ‘serum or transfusion’ hepatitis. This is the most fatal and common type of viral hepatitis among communities. The infection spreads through infected blood from mothers to their babies or by sexual routes. Symptoms are acute liver disease which turned to chronic one, hepatic carcinoma, liver cirrhosis, etc.


  • Alcoholics or liquor should be avoided.
  • Intercourse with more than one partner (promiscuous) should be avoided.

Question 5. What are the causative agent of tuberculosis and its symptoms?

Causative agent of tuberculosis and its symptoms:

Tuberculosis is caused by Mycobacterium tuberculosis. Mycobacterium enters through respiratory tract and reaches various parts of the body, such as lungs, intestine and lymph glands. After entering the body, the bacteria release s a toxin called tuberculin. The chances of infection are increased when a person inhales the infected droplets through coughing, sneezing, spitting of the infected person.

Symptoms: The patient of tuberculosis feels sick and weak with a gradual loss of appetite and weight. The symptoms of tuberculosis depends upon the region where the pathogen is entering and the type of organ it is infecting.

Question 6. Explain the reasons for the following factors.

  1. Balanced diet is necessary for maintaining healthy body.
  2. Health of an organism depends upon the surrounding environmental conditions.
  3. Our surrounding area should be free of stagnant water.
  4. Social harmony and good economic conditions are necessary for good health.


  • Food is necessary for the growth and development of the body. Balanced diet provides raw materials and energy in appropriate amount needed for the substances, likes protein, carbohydrates, fats, minerals, etc., which in turn are essential for proper growth and functioning of the healthy body.
  • Health is a state of being well enough to function well physically, mentally and socially and these conditions depend upon the surrounding environmental conditions. For instance, if unhygienic conditions prevail in the surrounding area, it is likely we might get infected or diseased.
  • This is so because many waterborne diseases and insect vectors flourish in stagnant water which causes various diseases in human beings.
  • Human beings live in societies and different localities like villages or cities, which determines the social and physical environment and hence, both are to be kept in harmony.
  • Public cleanliness is important for individual health. For better living conditions, lot of money is required. We need good food for healthy body and for this we have to earn more money. And also for the treatment of diseases, one has to be in good economic condition.

Question 7. Explain why becoming exposed to pathogens or infected with an infectious microbe does not necessarily mean developing noticeable disease.

Due to strong immune system, our body is normally fighting off microbes. We have cells which are specialized to kill the pathogenic microbes. These cells are active when the infecting microbes enter our body and if they are successful in removing the pathogen, we remain disease-free. So even if we are exposed to infectious microbes, it is not necessary that we suffer from diseases.

Question 8. Why are antibiotics not effective for viral disease?

Antibiotics not effective for viral disease:

Antibiotics generally block the biosynthetic pathways and they block these pathways of the microbes/bacteria. However, viruses have very few biochemical mechanisms of their own and hence, they are unaffected by antibiotics.

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