50 free Microbiology trivia questions with answers — science & nature quiz, new questions added Aug 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 50 questions with answers and explanations. Play the quiz
Q 01Which Dutch draper observed bacteria in 1676 and is called the 'Father of Microbiology'?
Antonie van Leeuwenhoek
He never wrote a book, describing his 'animalcules' in chaotic letters to the Royal Society, which published them.
Q 02In which Dutch city did Van Leeuwenhoek live and work for most of his life?
Delft
He opened a draper's shop there in 1654 selling linen, yarn and ribbon before turning to lenses.
Q 03Robert Hooke's first recorded microscope observation, in 1665, was of what?
The fruiting bodies of moulds
The Jesuit Athanasius Kircher may have beaten both Hooke and Van Leeuwenhoek, describing 'worms' in vinegar and milk in 1646.
Q 04Which Jesuit priest, writing on the plague in 1658, was likely the first person to see microbes?
Athanasius Kircher
He correctly said the disease was caused by microbes, though what he saw was probably blood cells; he was also a pioneer of the magic lantern.
Q 05Which 19th-century botanist founded bacteriology, describing Bacillus and drawing up the first bacterial taxonomy?
Ferdinand Cohn
He also discovered the dormant spores some bacteria form; Pasteur and Koch were his contemporaries.
Q 06Louis Pasteur's famous flask experiments were designed to disprove which theory?
Spontaneous generation
He used swan-neck flasks of fermentable liquid to show that no microbes appear 'without parents similar to themselves'.
Q 07Pasteur's technique of heating milk and wine to stop bacterial contamination is known as what?
Pasteurization
He also developed vaccines for anthrax and rabies and rescued France's silk industry from a silkworm disease.
Q 08What was the name of the nine-year-old boy first treated with Pasteur's rabies vaccine in July 1885?
Joseph Meister
Jupille was treated that October, and four American children were among those who then travelled to Pasteur's lab.
Q 09Robert Koch's 1876 discovery of which bacterium is considered the birth of modern bacteriology?
Bacillus anthracis
He went on to identify the tuberculosis and cholera agents and won the 1905 Nobel Prize.
Q 10World TB Day is marked on 24 March because on that date in 1882 Koch announced what?
The discovery of the bacterium behind it
His later 'cure', tuberculin, failed as a treatment but became a diagnostic test after his death.
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
He made the final modifications to the design in 1887 at Berlin University.
Q 13Who first suggested agar, a jam-making staple, for culture media in Koch's lab in 1881?
Fanny Hesse
She was working as a technician for her husband Walther Hesse; agar replaced gelatin, which melted at body temperature.
Q 21Which pediatrician discovered E. coli in the faeces of healthy people in 1885?
Theodor Escherich
The K-12 strain later became the workhorse of recombinant DNA work.
Q 22Roughly what fraction of environmental microbes can be grown in isolation in the lab?
Less than 1%
That is why microbiologists now lean on DNA methods such as 16S rRNA sequencing to identify bacteria.
Q 23Which DNA sequence is the standard molecular tool for identifying bacteria?
The 16S rRNA gene
The 18S gene plays a similar role for eukaryotes.
Q 14The Gram stain was developed in 1884 by a scientist of which nationality?
Danish
Hans Christian Gram devised it while working in the morgue of a Berlin city hospital.
Q 15In a Gram stain, Gram-positive bacteria retain which primary dye?
Crystal violet
Their thick peptidoglycan wall holds the stain; Gram-negative cells lose it and take the pink counterstain.
Q 16Bacterial cell walls are made of which polymer, absent from archaea?
Peptidoglycan
It is also called murein and is built from polysaccharide chains cross-linked by short peptides.
Q 17Spherical bacteria are called cocci. What are rod-shaped bacteria called?
Bacilli
'Bacillus' comes from the Latin for stick and 'coccus' from the Greek for grain or seed.
Q 18How long is a typical bacterial cell?
0.5 to 5 micrometres
That is about a tenth the size of a eukaryotic cell; Mycoplasma, at 0.3 micrometres, is as small as the largest viruses.
Q 19Thiomargarita magnifica, the largest known bacterium, can reach what length?
2 centimetres
It grows on sunken mangrove leaves in Guadeloupe and its discoverer at first took it for a fungus; the name means 'sulfur pearl'.
Q 20Under ideal conditions, roughly how quickly can E. coli reproduce?
Every 20 minutes
It was discovered in 1885 by paediatrician Theodor Escherich and is the most studied prokaryote in the world.
Q 24Who first classified archaea as separate from bacteria, in 1977?
Carl Woese
At the time only the methanogens were known; the groups were dubbed Archaebacteria and Eubacteria.
Q 25Archaea have cell membranes built from what kind of lipids, unlike bacteria and eukaryotes?
Ether-linked
They also have a unique motility structure, the archaellum, and many make methane.
Q 26The first virus ever identified, in the 1890s, infects which plant?
Tobacco
Dmitri Ivanovsky showed filtered sap stayed infectious in 1892 and Martinus Beijerinck named tobacco mosaic virus in 1898.
Q 27The word 'virus' comes from a Latin word meaning what?
Poison
'Virulent' dates to about 1400, and 'virus' meant an infectious agent as early as 1728, long before viruses were found.
Q 28Viruses that infect bacteria are called bacteriophages. What does the Greek root 'phagein' mean?
To devour
Félix d'Hérelle coined the name at the Pasteur Institute in 1917, two years after Frederick Twort's independent discovery in London.
Q 29Alexander Fleming discovered penicillin in 1928 from a mould of which genus?
Penicillium
The species was Penicillium rubens; Florey and Chain purified the drug in 1940 and shared the 1945 Nobel Prize with him.
Q 30Six years before penicillin, Fleming discovered which enzyme in his own nasal mucus?
Lysozyme
He found it in 1922 along with a bacterium it destroyed, which he named Micrococcus lysodeikticus.