Microbiology Trivia
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98 free Microbiology trivia questions with answers — science & nature quiz, new questions added Oct 2026.
45 free Microbiology trivia questions with answers. Microbiology is the study of everything too small to see, and this quiz covers the people, the tools and the organisms. It runs from Athanasius Kircher and Antonie van Leeuwenhoek's 'animalcules' through Semmelweis and handwashing, Lister and carbolic acid, Pasteur's swan-neck flasks and rabies vaccine, Koch's postulates and the tuberculosis bacillus, Hans Christian Gram's stain, Fanny Hesse's agar and Julius Petri's dish, to Fleming's mouldy plate, Twort and d'Hérelle's bacteriophages, Carl Woese's third domain, and Barry Marshall drinking a beaker of Helicobacter. It also asks about the organisms themselves: cocci and bacilli, peptidoglycan, endospores that survive for centuries, E. coli's 20-minute doubling time, the centimetre-long Thiomargarita magnifica, 'Conan the Bacterium', Prochlorococcus, tardigrades in space and the 38 trillion bacterial cells in your body. Easy questions ask what pasteurisation is and what a Petri dish holds. Medium ones cover the founders, the stains and the famous experiments. Hard ones want the year Gram devised his stain, who first suggested agar, the size of a Mycoplasma cell and how many postulates Koch wrote. Every answer has been checked against reference articles on the science and its history, and each question shows its citation once you have answered. Built for biology students, quiz nights and anyone who has ever wondered what is living on their hands.
30 of 98 questions with answers and explanations. Play the quiz
Q 01In 1796 Edward Jenner infected a boy with cowpox to protect him against which deadlier disease?
Smallpox
Smallpox: Latin vacca, 'cow', is why Jenner's cowpox method gave us the word vaccination.
Q 02In which Dutch city did Van Leeuwenhoek live and work for most of his life?
Delft
Delft: a cloth merchant there with no university education, he ground his own lenses and became the first person to see bacteria.
Q 03Robert Hooke coined the biological term 'cell' after studying thin slices of what?
Cork
Cork: the book reporting it, Micrographia, so gripped Samuel Pepys that he sat up until 2 a.m. reading it.
Q 04Lyme disease, a bacterial infection, is usually passed to people through the bite of what?
Ticks
Ticks: the illness takes its name from Lyme, Connecticut, where a mysterious cluster of cases in 1975 led doctors to identify it.
Q 05Tetanus is often blamed on rusty nails, but what actually causes it?
Bacteria from soil
Bacteria from soil: rusty nails are simply outdoor objects that tend to carry dirt, and deep, dirty wounds give the germs their best chance.
Q 06Louis Pasteur's famous flask experiments were designed to disprove which theory?
Spontaneous generation
Spontaneous generation: his swan-necked flasks let air in but trapped falling dust, so the boiled broth stayed free of microbes for months.
Q 07Pasteurization is best known for milk, but Louis Pasteur first developed it to stop which drink spoiling?
Wine
Wine: he showed that unwanted microbes caused wine's 'diseases' and that gentle heating destroyed them, and the method reached milk only later.
Q 08Before giving his rabies vaccine to a bitten boy in 1885, Louis Pasteur had tested it on which animals?
Dogs
Dogs: he had protected dogs even after they were bitten, and the boy's recovery helped bring in public donations for the Institut Pasteur.
Q 09In 1876 Robert Koch gave the first proof that a specific bacterium causes which disease?
Anthrax
Anthrax: he did it as a country doctor working in his own four-room flat, with a microscope his wife had given him.
Q 10World TB Day falls on 24 March because on that date in 1882 Robert Koch announced what?
The bacterium behind TB
The bacterium behind TB: the 'cure' Koch later promoted, tuberculin, was hoped to heal the disease but proved ineffective.
Q 11How many criteria make up Koch's postulates for linking a microbe to a disease?
Four
They were formulated with Friedrich Loeffler in 1884 and refined by Koch in 1890; modified versions now exist for prions.
Q 12The shallow lidded dish used to culture microbes is named after which assistant of Robert Koch?
Julius Richard Petri
Julius Richard Petri: Koch's team had been covering their plates with heavy bell jars to keep out dust, until Petri simply added a slightly larger glass lid.
Q 13Agar, the jelly Fanny Hesse is credited with suggesting for growing bacteria, is made from what?
Seaweed
Seaweed: unlike the gelatin used before, agar stays solid at the warm temperatures where bacteria grow best.
Q 21Which pediatrician discovered E. coli in the faeces of healthy people in 1885?
Theodor Escherich
Theodor Escherich: studying babies' gut bacteria, he found it in sick and healthy children alike, and the genus Escherichia was later named in his honour.
Q 22Which DNA sequence is the standard molecular tool for identifying bacteria?
The 16S rRNA gene
The 16S rRNA gene: comparing it is how Carl Woese and George Fox showed in 1977 that archaea are a separate line of life, not bacteria.
Q 23Archaea living in the digestive tracts of cows produce which gas?
Methane
Methane: a potent greenhouse gas, which is why livestock are counted with fossil fuels and landfills in tallies of its emissions.
Q 14The Gram stain was devised in Berlin in 1884 by Hans Christian Gram, a scientist of which nationality?
Danish
Danish: his first report modestly called the method 'very defective and imperfect', yet it is still a standard first step in identifying bacteria.
Q 15In a Gram stain, Gram-positive bacteria retain which primary dye?
Crystal violet
Crystal violet: iodine locks the purple dye inside thick cell walls, while thin-walled gram-negative cells lose it to an alcohol wash and turn pink.
Q 16Bacterial cell walls are made of which polymer, absent from archaea?
Peptidoglycan
Peptidoglycan: this mesh-like wall is what penicillin attacks, damaging it until the bacterium is destroyed.
Q 17Spherical bacteria are called cocci, so what are rod-shaped bacteria called?
Bacilli
Bacilli: Latin for 'little staffs', and the word bacteria itself comes from Greek for a small staff, because the first ones seen were rods.
Q 18Which part of our cells, about the size and shape of a bacterium, is thought to have begun as one?
The mitochondrion
The mitochondrion: one clue is its own small set of DNA, which looks more like a bacterium's than like the DNA in our nucleus.
Q 19Thiomargarita magnifica, described in 2022 as the largest known bacterium, typically grows to about what length?
1 centimetre
1 centimetre: big enough to see by eye, it also wraps its DNA in membrane sacs, unlike the loose DNA of most bacteria.
Q 20Under ideal conditions, roughly how quickly can E. coli reproduce?
Every 20 minutes
Every 20 minutes: at that pace a single cell could, in theory, become over two million bacteria in just seven hours.
Q 24An enzyme from a heat-loving bacterium found in hot springs made which DNA technique practical?
PCR
PCR: its enzyme survives the near-boiling heat of each cycle, so scientists no longer had to add fresh enzyme again and again.
Q 25The first virus ever identified, in the 1890s, infects which plant?
Tobacco
Tobacco: in 1898 Martinus Beijerinck confirmed that the germ slipped through filters that trap bacteria, yet it multiplied inside living plants.
Q 26The word 'virus' comes from a Latin word meaning what?
Poison
Poison: English doctors long used 'virus' for poisonous or infectious matter, and only pinned it on these tiny germs once they were discovered in the 1890s.
Q 27Bacteriophages, viruses that infect bacteria, take their name from a Greek word meaning what?
To devour
To devour: d'Herelle's 'bacterium-eaters' were soon put to work as medicine, and from the 1920s to the 1940s phage therapy treated many infections.
Q 28Alexander Fleming discovered which enzyme after putting his own nasal mucus onto a dish of bacteria?
Lysozyme
Lysozyme: it attacked only a few harmless kinds of bacteria, so it had little use as a medicine.
Q 29Ignaz Semmelweis cut childbed fever deaths in 1847 by insisting doctors do what?
Wash their hands in chlorinated lime
Wash their hands in chlorinated lime: his doctors and students came to deliveries straight from autopsies, while the midwives' clinic, which did none, saw far fewer deaths.
Q 30Joseph Lister pioneered antiseptic surgery in Glasgow using which chemical?
Carbolic acid
Modern-day phenol; he used it on instruments, sutures, wounds and surgeons' hands.