Edward Jenner created the vaccine for smallpox two centuries ago.

This is the correct answer. Skin infections are caused by fungi.

This is the correct answer as all the statements about vaccines are correct.

This is the correct answer as the headache is just a symptom of a disease, but does not indicate the disease.

Malaria is caused by protozoan.

This is correct. Peptic ulcers are painful bleeding areas within the stomach and duodenum.

This is the correct answer as all the statements are correct. Diseases which last for a short time are called acute diseases. Diseases which last for a very long time are called chronic diseases. Diseases are classified as chronic or acute on the basis of duration.

Infectious diseases are spread by microbes and spread very quickly in a community. This is the correct answer.

This is caused by the protozoan Leishmania.

Elephantiasis is caused by worms and is a chronic disease.

Viruses are the disease-causing microbes that live and remain active inside the host cells.

This is the correct answer as syphilis and AIDS are transmitted by sexual contact.

Sleeping sickness is a disease caused by a protozoan parasite Trypanosoma brucei. The tsetse fly spreads it.

This is incorrect. Non-communicable diseases are caused by nutritional deficiency. Communicable diseases can be due to degeneration of organs or malfunctioning of organs due to infection.

This is caused by a protozoan.

The virus causing Japanese encephalitis or brain fever enters through a mosquito bite and it goes on to infect the brain.

This is the correct answer as both statements b and c are incorrect. Members of a group of microbes have some traits, i.e. many biochemical processes inside their cells are similar. As a result, drugs that block one of these biochemical mechanisms in one member of the group will be effective against many other members of the group. The same drug will not be effective against a microbe belonging to a different group. Antibiotic penicillin acts against bacteria by blocking the biochemical pathways important for bacteria.

This is the correct statement. Making antiviral medicines is harder because viruses have few biochemical mechanisms of their own. They enter our cells and use our machinery for their life processes.

These are the type of vaccines that are used for diptheria and tetanus. In this type of vaccine, the toxoids produced by the bacteria are made harmless. Toxoids are used to stimulate antibody production, but there is no risk of infection by the pathogen.

This is the correct answer as communicable diseases can be spread by air, contaminated drinking water, vectors such as mosquitoes and other animals, and sexual contact.