IMO Practice Test — Human Health and Disease
6 Questions • 15 min • Olympiad level
15:00
Question 1 of 6
Draining stagnant water and using mosquito nets fights malaria mainly by:
Controlling the vector (mosquito)
Killing Plasmodium directly in soil
Boosting antibodies
Making a vaccine
Explanation: Removing breeding sites and avoiding bites controls the Anopheles vector that carries the parasite.
Question 2 of 6
A second infection by the same germ is often milder because acquired immunity has:
Memory cells that respond faster
No effect
More germs
Removed the skin
Explanation: Memory cells from the first exposure mount a quicker, stronger response on re-exposure.
Question 3 of 6
Vaccination protects a whole community partly through herd immunity, which means:
When most people are immune, the germ spreads less to everyone
Animals get vaccinated
No one needs vaccines
The germ grows faster
Explanation: High immunity in the population breaks transmission chains, indirectly protecting the unvaccinated too.
Question 4 of 6
AIDS makes a person prone to many other infections because HIV:
Destroys immune cells that fight infection
Strengthens immunity
Adds antibodies
Makes vaccines
Explanation: By killing key immune cells, HIV leaves the body unable to defend against other pathogens.
Question 5 of 6
Quitting tobacco reduces cancer risk because tobacco smoke contains:
Carcinogens that damage cells
Antibodies
Vaccines
Vitamins
Explanation: Carcinogens in smoke trigger the cell changes that lead to cancer, so avoiding them lowers risk.
Question 6 of 6
Early detection (screening) improves cancer survival mainly because it allows treatment before the tumour:
Spreads (metastasises) to other organs
Becomes an antibody
Turns into a vaccine
Disappears on its own
Explanation: Treating a localised tumour before metastasis is far more successful than after it spreads.