Community is composed of individuals. If all the individuals have good personal health, the entire community will be healthy. Also, if the community is having hygienic surroundings, the individual health will be good. Thus, the two are interdependent, i.e. they depend on each other. The terms ‘overdependent’, ‘independent’ and ‘intradependent’ are not correct for this interdependent relation.

Transmission of disease means transfer of disease causing agents from diseased/infected person to the healthy one. AIDS is transmitted by sexual contact. Cholera and typhoid are transmitted by infected food and water while malaria is transmitted by the vector; female anopheles mosquitoes.

The diseases caused by microbes are generally transmitted quickly when microbes are transferred from the diseased to the healthy person and hence, they are termed “infectious” diseases, for e.g. common cold, skin infections, etc. 

Clean boiled water with sugar and salt added to it is given to avoid dehydration of body tissues. Our body loses excess of water during stomach and intestinal infection due to loose stools. This happens during gastrointestinal disorder. In brain, kidney and liver disorders, our body does not lose excess of water and hence, the above said water + sugar + salt does not need to be administered.

Penicillin is an antibiotic obtained from the fungus ‘Penicillium notatum’ and it works against bacteria. Quinine and chloroquine are drugs which are used to treat malaria. Anti-Tetanus Serum (ATS) is a vaccine used to prevent tetanus. None of these is obtained from fungus and hence, they are not antibiotics.

 A disease transmitted by sexual contact is AIDS.

The principle of vaccination is based on the property of memory of the immune system as it gives an exposure for the first time so that it can act actively when the body is attacked for the second time by the same pathogen. So, it is memory.

The immune system works against disease-causing microbes and prevents diseases. The nervous system transmits impulses, the muscular system helps in the movement of the body and the respiratory system helps in the exchange of gases.

SARS is caused by bacteria (i.e. 1 is correct), AIDS is caused by Human Immunodeficiency Virus (HIV) (i.e. 2 is correct) and common cold is caused by different kinds of viruses (i.e. 4 is also correct). (1), (2) and (4) are correctly matched, but (3) is incorrect because malaria is caused by a protozoan, i.e. Plasmodium is transmitted by the vector, i.e. female anopheles mosquitoes.

Animal (dog and cat usually) bite causes rabies due to transmission of rabies virus. Typhoid and tetanus are caused due to bacteria transmitted by food, water, soil, etc while AIDS is caused by virus transmitted by exchange of body fluids between a healthy person and an infected person.

Excessive dehydration, due to loose motions and vomiting are symptoms of diarrhoea which is a disorder of gastrointestinal tract. Thus, (4) is the correct answer. Malaria is caused due to infection of plasmodium in blood and its effect on liver. Tuberculosis is an ailment of lungs and tetanus is a disorder affecting the muscular system.

In elephantiasis, the person’s limbs, i.e. feet, legs, arms and hands are highly swollen due to accumulation of water in the cells. The person looks bulky and his limbs are swollen. It is compared to elephant’s limbs so the disease is termed “elephantiasis”. In ascariasis, the worm named ascaris infects the stomach and intestine, thereby making the person weak because they feed on the food material present in the blood of the person (host). Similarly, tuberculosis is caused due to bacteria and in this disease, lungs and respiratory systems are affected. In this, mucus begins to collect in lungs gradually leading to inefficient gaseous exchange, frequent cough and at later stages, bleeding occurs in the throat. Thus elephantiasis, ascariasis and tuberculosis are caused due to infectious agents and they take a long time inside our body as they are treated slowly. They leave behind long term health effects which make the body weak. Thus, they are chronic. But influenza, i.e. common cold lasts for few days. It affects us severely, but it does not make us weak later on. Hence, it is an acute disease.

Genetic disorders result from errors in the DNA of our body cells. Hormonal disorders (for e.g. excessive growth, appearance of facial hair in females, etc) are the results of imbalanced secretion of hormones produced within the body. Similarly, if any body organ malfunctions, i.e. it does not function in proper order, then it is an internal cause. But if there is malnutrition, then the cause is purely external and not within our body. We should remember that cause may be external or internal, but the effect is seen on the general health of our body.

During any accident, wounds occur and they are exposed to air and soil. The air and soil may contain tetanus-causing microbes. Hence, the person is immediately given anti-tetanus injection.