Class 8 Science Lesson 2 Health and Diseases – answers

Class 8 Science Chapter 2 Health and Diseases Questions and Answers

Std 8 Science Chapter 2 Health and Diseases Textbook Questions and Answers


1. Distinguish between- Infectious and non-infectious diseases.

Infectious diseases Non-infectious diseases
1. Diseases which occurs through infections and body contacts are called as infectious diseases. 1. Diseases which do not occur through infections and body contacts are called as non-infectious diseases.
2. Infectious disease can be transmitted through contaminated air, water, food or vectors (insects and animals) . 2. Non-infectious diseases are not transmitted through any medium.
3. These are caused due to infections from either bacteria, virus or protozoan. 3. Some of these diseases are caused due to hereditary causes, some are caused due to deficiency of the nutrients.
4. their symptoms are seen suddenly 4. Their symptoms are seen gradually.
5. E.g. Tuberculosis, hepatitis, leprosy, cough and cold, etc. 5. E.g. cold and cough, diabetes, cancer, heart diseases, etc.

2. Identify the odd term.

a. Malaria, hepatitis, elephantiasis, dengue.

Ans. Hepatitis is the odd one out because it is a type of viral infection while the rest of three are spread through the bite of mosquitoes.

b. Plague, AIDS, cholera, T.B.

Ans. AIDS is the odd one out because it is a viral disease while the rest of them are bacterial diseases.

3. Answer in one to two sentences.

a. Which are various media of spreading the infectious diseases?

Ans. Infectious diseases can spread through air, water, blood to blood contact and animal vectors.

b. Give the names of five non-infectious diseases other than given in the lesson.

Ans. Non infectious diseases- arthiritis, cataract, osteoprosis, multiple sclerosis and Alzeimer’s.

c. Which are the main reasons of diabetes and heart diseases?

Ans. Reasons of heart diseases include smoking, alcoholism, diabetes, hypertension, obesity, lack of physical exercise, mental stress, anxiety and improper diet. Reasons of diabetes include obesity, lack of physical exercise, mental stress, improper diet and hereditary.

4. What can be achieved / can be prevented?

a. Drinking boiled and filtered water.

Ans. Boiling and filteration are methods of purifying water which makes it suitable for consumption. Drinking boiled and filtered water can help in prevention of water borne diseases such as typhoid, cholera, etc. Most of the water borne diseases are transmitted through the consumption of contaminated water in some or the other form. 

b. Avoiding smoking and alcoholism.

Ans. Smoking and alcoholism are two of the devils of our health and society. Smoking leads to various kinds of respratory disorders and hinders the process of respiration. It can lead to diseases such as lung cancer. On the other hand, consumption of alcohol, effects the nervous as well as the digestive system of our body. Avoiding alcohol and smoking can protect indivisuals from various diseases and can help in living a healthy and stress free life.

c. Regular balanced diet and exercise.

Ans.  Balanced diet and exercise are key to good health. Both of these in combination helps our systems to function properly, helps maintain a healthy weight, reduces body fat, provides the body with energy, promotes good sleep and makes us feel better about ourselves.

d. Proper checking of blood before blood donation.

Ans.  Proper checking of blood before blood donation is required to check that the blood to be transferred is safe in all respects. There are chances of transfer of infectious diseases form the donor, if he/she is suffering from any such diseases.

Another important factor for checking of blood before donation is to check that the donor is not anemic (does not have anemia).

5. Read the passage and answer the questions.

Master ‘X’ is a 3 year old child. He is living with his family in a slum. Public toilet is present near his house. His father is drunkard. His mother does not know the importance of balanced diet.

a. Master ‘X’ can suffer from which different possible diseases in above conditions?

Ans. Since, the house of master X is near the toilet and he lives in a slum area, the chances are that there is less cleaniliness in that area. There are chances that he may suffer from diseases like salmonellosis, shigellosis, diarrhoea, trachoma, gastroenteritis, giardiasis, tapeworm infection and threadworm infection.

b. How will you help him and his family in this situation?

Ans. In this case, the famliy needs to be made aware about cleanliness in and around their houses. There is a need to explain them the importance of balanced diet for them and their child. Since, the father is a drukyard, he needs counselling and treatment to get rid of the habit of alcoholism.

c. Which disease can occur to the father of master ‘X’?

Ans. The father of master X is a drunkyard which means he might suffer from diseases such as heart diseases, liver cirrhosis, ulcers and gastrointestinal ptoblems, brain damage etc.

6. Give the preventive measures of following diseases.

a. Dengue.

Ans. Dengue is a mosquito borne disease which is transmitted by Aedes mosquitoes which grow in clean and stagnant water. The breeding of this mosquito can be prevented by adopting the following steps:

  • larve-eating fishes should be introduced in ponds
  • collection and storage of water should always be done in closed vessels
  • potted plants should have proper drainage to avoid collection of water in the pots
  • pesticides should be used against mosquitoes as and when required

b. Cancer.

Ans. Preventive measures for cancer:

  • have a healthy diet
  • exercise regularly
  • avoid smoking and alcohol
  • go for regular health checkups

c. AIDS.

Preventive measures for AIDS are:

  • avoid sexual contact with unknown persons
  • screening of blood before transfusion
  • avoid sharing of needles

7. Explain the importance.
a. Balanced diet.

Ans. A balanced diet is a diet containing all nutrients (carbohydrates, fats, proteins, vitamins, etc.) in the right quantities. A balanced diet helps us in various ways:

  • provides us with important nutrients required for the growth of body
  • helps us to stay fit and free from diseases
  • helps in strengthening the immune system
  • helps our systems to function properly
  • helps maintain a healthy weight
  • reduces body fat
  • provides the body with energy
  • promotes good sleep and makes us feel better about ourselves

b. Physical exercise / Yogasanas.

Ans. Importance of exercise and yogasanas are:

  • reduces the risk of heart attack
  • helps in managing weight better
  • helps in maintaining blood cholesterol level
  • lowers the risk of type 2 diabetes and some cancers
  • helps in maintaining the blood pressure levels
  • helps in attaining stronger bones, muscles and joints and lowers the risk of osteoporosis
  • boosts the energy levels, makes you feel relaxed

8. Make a list.
a. Viral diseases.

Ans. Measels, Mumps, Swine flu, Chicken pox

b. Bacterial diseases.

Ans. Tuberculosis, Diptheria, Tetanus, Cholera, Typhoid

c. Diseases spread through insects.

Ans. Dengue, Malaria, Plague

d. Hereditary diseases.

Ans. Diabetes, Hypertension, Cancer

 9. Write the information on modern diagnostics and treatments of cancer.
 Ans. Diagnostics of cancer:
There are many techniques whiich are used in the diagnosis of cancer and their application depends upon the type of cancer. Biopsy, histopathological studies of bone and blood, radiography (use of X-rays), CT (computed tomography) and MRI (magnetic resonance imaging) are used in diagnosis of cancer. Radiography, CT and MRI are the modern techniques used in cancer diagnosis.
Computed tomography uses X-rays to generate a three-dimensional image of the internals of an object. MRI uses strong magnetic fields and non-ionising radiations to accurately detect pathological and physiological changes in the living tissue.

Treatment of cancer:
Cancer is treated using 3 major approaches depending on the type of cancer. These 3 approaches are- surgery, radiotherapy and chemotherapy. In surgery, the tumor is removed surgically from its site and can be used in specific cases only. Radiotherapy is a technique in which the cancer cells are irradiated with radiations taking care of the normal tissues which surround the cancer cells.
Chemotherapy uses different kinds of drugs for the treatment of cancer. These chemotherapeutic drugs are specific for particular tumors and have side effects such as hair loss, anemia, etc.
Most of the cancers are treated by the combination of these 3 approaches.

Q 10. Enlist the names and composition of the medicines present at your home.

Ans. The following medicines are found in our houses:
Paracip- Paracetamol/Acetaminophen
Digene-  Dried Aluminium Hydroxide, Magnesium Aluminium Silicate Hydrate, Magnesium Hydroxide, Simethicone
Volini- Diclofenac diethylamine BP, Linseed Oil BP (Oleum Lini), Methyl salicylate, Menthol IP, Benzyl Alcohol IP.
Vomikind- Ondansetron

Extra question

  1. Health is a state of complete physical, mental and social well-being.
  2. Condition of disturbances in physiological or psychological processes of body is called as disease.
  3. Diseases spread through contaminated air, water, food or vectors (insects and other animals) are called as infectious diseases.
  4. Dengue is spread by Aedes aegypti.
  5. Dengue disease is caused by DEN-1, 2 virus belonging to the type- flavivirus.
  6. Infection for swine flu occurs through pigs and humans.
  7. Viruses of swine flu are spread through sweat of infected person.
  8. Malaria is caused due to female Anopheles  while elephantiasis due to female Culex.
  9. Anopheles and Aedes grow in clean water while Culex in dirty, sewage water.
  10.  Diagnostic facilities are available in National Institute of Virology (NIV).
  11.  First case of swine flu was reported in Mexico in 2009.
  12.  Swine flu is caused by the virus influenza A (H1 N1 ).
  13.  AIDS- Acquired Immuno Deficiency Syndrome .
  14.  HIV- Human Immunodeficiency Virus.
  15.  In AIDS disease, victim suffer from various diseases due to progressive weakening of natural immunity.
  16.   To test AIDS ELISA test is used for its proper diagnosis.
  17.  HIV was first reported in an African species of Monkeys.
  18.  Rabies occurs due to the bite of the infected dog, rabbit, monkey, cat etc.
  19.  Hydrophobia is one of the important symptom of this rabies disease.
  20.  The person affected by rabies shows extreme fear for water.
  21.  Rabies is fatal disease.
  22.   Rabies symptoms start to appear within 90 – 175 days of dog bite.
  23.  Uncontrolled and abnormal cell growth is called as cancer.
  24.  Group or lump of cancerous cells is called as malignant tumor.
  25.  Cancer can occur in various organs like lungs, mouth, tongue, stomach, breast, uterus, skin and tissues like blood.
  26.  Hormone- insulin produced in pancreas controls the level of sugar and glucose in blood.
  27.  Insulin is secreted in low quantity, glucose level cannot be controlled; this disorder is called as diabetes.
  28.  Controlled diet helps to prevent some types of cancers.
  29.  Physical exercise along with modern treatment is more beneficial to cure the cancer.
  30.  Efficiency of the heart decreases due to decreased blood supply and thereby oxygen and nutrient supply to the heart muscles causes heart diseases.
  31.  Overdose of medicines may affect our body.
  32.   Overdose of pain killers may damage nervous system, excretory system, liver.  
  33.  Overdose of antibiotics may lead to nausea, stomach ache, dysentery, rash, white patches on tongue.
  34.  Generic medicines are also known as general medicines.
  35.  Generic medicines are at par in quality with branded medicines.
  36.  Lifestyle includes the daily routine and the type of food.
  37.  Vaccination is important to prevent the infectious diseases.
  38.  One unit blood donated by a person can fulfill the need of three persons at a time.
  39.  One can save the life of twelve persons by donating the blood for four times a year.
  40.  C.O.L.S.compression only life support.

Some Important days

7th April – World Health Day

29th September – World Heart Day

14th June – World Blood Donation Day

14th November – World Diabetes Day