1. Write the full form of AIDS. List four modes of transmission of virus of this disease.


AIDS – Acquired Immuno Deficiency Syndrome Modes of transmission of AIDS:

a. Through sexual contact

b. Through blood trsnsfusion

c. From mother to child d. Through infected needled or syringes

Q  2. (i)Which disease is more harmful: Acute or Chronic disease? Why?

(ii)Why are we advised to take balanced and nourishing food when we are sick?


(i) Chronic disease is more harmful because chronic diseases have drastic long term effects on people’s health as compared to acute disease.

(ii) (a) Such food are devoid of oil or fat and spices and it is digested easily.

(b) It provides sufficient energy for recovery after the disease.

(c)It provides adequate amount of nutrients required for regeneration of cells and tissues. (Any two points)

Q  3. Explain any three reasons to justify that prevention of diseases is better than their cure.


(i)Once someone gets a disease, his or her body functions gets damaged  and may never recover completely.

(ii)The treatment of a disease takes time so the person is likely to be bedridden for sometime, even if he is given proper treatment.

(iii)  The person suffering from an infectious disease can serve as the medium for further spread of infection to other people.

Q  4. Explain any three means through which infectious disease spread.


1. Through air: The disease spread through sneezing or coughing through water droplets. E.g. – Common cold, Tuberculosis.

2. Through water: It can spread through consuming contaminated water, open defecation etc. E.g.- Cholera, Typhoid

3. Sexual contact: Diseases spread through sexual contact or exchange of body fluids. E.g. – Syphilis, AIDS

4. Through vectors: Animals like flies and mosQ  uitoes carry infecting agent from sick person to healthy person. E.g.-Rabies, Malaria (Any three)

Q  5. List any two conditions essential for good health.


Conditions essential for good health:

i. Availability of sufficient and nutritious food

ii. Better sanitation or clean environment

Q  6. If you go to the hospital to meet your friend suffering from malaria, what are the chances of malaria spreading to you and your friends?


Malaria is caused by Plasmodium which is carried by the bite of female Anopheles mosquito. So, it is not spread by the diseased patient.

Q  7. Name two diseases caused by each of the following :

(i) Bacteria

(ii) Virus

(iii) Fungi


(i) Bacterial diseases – cholera and tuberculosis.

(ii) Viral diseases – common cold and influenza.

(iii) Fungal diseases – Food poisoning and skin infections.

Q  8. Differentiate between acute and chronic diseases.


Acute Disease Chronic disease Lasts only for a short period of time Lasts for a long time Can be cured quickly and relatively easily Need long periods of treatment There are no lasting side effects  Have drastic long-term effects on people’s health.  

Q  9. Why is public cleanliness important for individual health?


Many public places are left messy and unpleasant. Some industries pollute the surrounding environment. In many drains, water flows over it or the water is stagnant leading to breeding of mosQ  uitoes and flies. All these enhance the growth of germs and chances of infection. Therefore, public cleanliness is important for individual health.

Q  10. Why is common cold an acute disease?


Common cold is an acute disease because the symptoms are easily visible and lasts for a shorter duration.  

Q  11. What preventive measures can be taken against infectious diseases?


Diseases can be prevented in general and specific ways.

i. General ways of prevention are:

a. Air-borne diseases can be controlled by adopting living conditions that are not overcrowded.

b. Water-borne diseases can be prevented by providing safe drinking water.

c. Vector-borne infections can be checked by making vector free environment.

ii. Specific way of preventing infectious diseases is to immunize surrounding individuals against infectious diseases.

Q  12. Write the causative agents for the following diseases:

i. Tuberculosis

ii. Jaundice

iii. Malaria

iv. Polio


i. Mycobacterium tuberculosis

ii. Hepatitis B virus

iii. Plasmodium sp.

iv. Polio virus

Q  13. (a)What are vectors?

(b)In many species of mosQ  uitoes the males do not prefer human blood, but females do. State why?


(a) Animals that carry the infecting agents from a sick person to another potential host are called vectors.

(b) Females need highly nutritious food (in the form of blood) to lay mature eggs.

Q  14. Who is responsible for maintaining the community health? How? List any three points.


Panchayat or Municipal corporation is responsible for maintaining the community health.Community health is maintained by the following ways:

(i) Supply of clean and safe drinking water.

(ii) Provision for proper sewage and disposal of garbage.

(iii) Provision for preventive vaccinations against a number of diseases.

Q  15. (a) Name a worm which is found in our small intestine. (b) Name the bacteria which can cause acne.

(c) Which protozoan is responsible for sleeping sickness?

(d) Which disease is caused by the protozoan Leishmania?


(a) Ascaris

(b) Acne is caused by Staphylococci.

(c) Sleeping sickness is caused by Trypanosoma.

(d) Kala-azar

Q  16. (i) What is incubation period?

(ii) Name any two diseases for which vaccines are available.


(i) Time period from the time at which an organism is exposed to the disease causing agent until the appearance of the first symptoms is called incubation period.

(ii) Tetanus and diptheria.

Q  17. State and explain the steps of the principle of treatment of diseases.


There are two ways to treat an infectious disease:

(i)One way is to reduce the effect of the disease. Some treatments can reduce the symptoms of the disease. For example – medicines can bring down fever, reduce pain or loose motions.

(ii)The other way is to kill the microorganisms or infectious agents by medicines.

Q  18. What is an antibiotic? Give its one example


Antibiotic is a chemical substance secreted by microorganisms which at low concentration levels, have the ability to destroy or inhibit the growth of pathogens. Example – Penicillin

Q  19. Name the causal organism of AIDS. Why a person suffering from AIDS cannot fight even very 

minor infections?


The causal organism of AIDS is HIV virus. The virus damages the immune system and reduces its function. So, the body can no longer fight off even minor infections.

Q  20. For most microbes the organ they target is related to their point of entry. Furnish details of your answer under the following headings: Organ of entry Kind of microbe Target organ Disease caused Mouth Bacteria     Mouth Virus    


Organ of entry Microbe Target organ Disease caused Mouth Bacteria Gut lining Typhoid Mouth Virus Liver Jaundice

Q  21. Enlist some intrinsic and extrinsic factors which affect human health.


Intrinsic factors: i. Malfunctioning of some vital body organs and immune system. ii. Genetic disorder. iii. Hormonal imbalances. Extrinsic factors: i. Unbalanced or inadeQ  uate diet. ii. Disease causing microorganisms. iii. Environmental pollutants. iv. Bad food and drinking habits.

Q  22. Name the organ affected when a person is suffering from jaundice.


Jaundice is most often the result of a disorder affecting the liver.

Q  23. Give one example of each:

i. Infectious diseases

ii. Non-infectious diseases

iii. Acute diseases

iv. Chronic diseases


i. Malaria

ii. Heart-attack

iii. Common cold

iv. Tuberculosis

Q  24. State in tabular form the mode of transmission of each of the following diseases.




(d)Japanese encephalitis


Name of the disease Mode of transmission Syphilis Sexual contact Tuberculosis Air Jaundice Water Japanese encephalitis Mosquito bite

Q  25. Differentiate between acute and chronic diseases giving examples.


Acute Disease Chronic Disease Diseases in which the symptoms are Q  uickly visible in the body and last for a shorter duration Diseases which are long-term, with their symptoms lasting for months or years. Example- Common cold Example- Tuberculosis

Q  26. What is AIDS? Mention any two ways in which it spreads from an infected person to healthy person.


AIDS (AcQ  uired immunodeficiency syndrome) is a syndrome caused by a virus called HIV (Human Immunodeficiency Virus). Two ways in which it spreads from an infected person to healthy person are: Sexual contact that involves semen, vaginal fluids or blood. Direct blood contact, particularly through sharing injection drug needles

Q  27. What precautions will you take in your school to reduce the incidence of infectious diseases?


To reduce the infection of infectious diseases, following precautions can be taken in schools:

1. Drinking clean and hygienic water

2. Preventing accumulation of water in surroundings 3. Keeping the toilet neat and clean

4. Avoiding consumption of uncovered food and other eatables

5. Using a handkerchief to cover the mouth while sneezing or coughing

6. Encouraging students and their parents to take vaccinations against infectious diseases

Q  28. What are congenital disorders? How do they occur? Can they be cured?


Congenital disease is a disease or disorder that is inherited genetically and is present since birth. These diseases are caused because of genetic abnormalities, metabolic disorders or malfunctioning of any organ in body. No, congenital diseases cannot be cured. They are permanent.

Q  29. Differentiate between healthy and disease free.


Healthy Disease Free

i. It is a state of complete physical, mental and social well being.  

ii. A healthy person will be disease free.

i. It is a state of absence of discomfort or disorder in any part of body.

ii. A disease free person can be healthy or unhealthy.

Q  30. Although Archana has been suffering from a cold and cough she decided to appear for her class test. Classmates seated close to her had an exposure to the infection being carried by Archana. However, only one of them actually suffered from cold and cough. Explain,what prevented rest of those classmates from catching cold and cough in spite of their exposure to the infection.


Immune system of individuals fight off infection carrying microbes.   The immune system of those who did not suffer with cold and cough successfully caught off the microbes to which they were exposed.