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This cell trivia quiz has 70 free questions with answers and covers the building blocks of life from every angle. You will meet the organelles (the nucleus, ribosomes, lysosomes, chloroplasts and the one everyone calls the powerhouse), the stages of mitosis and meiosis, the cell cycle, membranes and osmosis, and the strange edge cases: the human cell with no nucleus, the cell you can see without a microscope, and the cancer cells that have been dividing since 1951. There is plenty of history too. Robert Hooke and his slice of cork, the Delft draper who first saw bacteria, Schleiden, Schwann and Virchow's cell theory, and the Nobel Prizes handed out for ribosomes, ATP synthase, cell-cycle regulators and programmed cell death. Questions range from easy ones a biology student will breeze through to expert ones on who coined which term and when. Every answer has been checked against a reliable primary or encyclopaedic source, so you can use these for a classroom warm-up, a study session or a science quiz night.
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Q 01Who coined the term "cell" in 1665 after examining thin slices of cork under a microscope?
Robert Hooke
The little compartments in cork reminded him of the small rooms, or cells, that monks lived in. What he actually saw were the empty walls of dead plant cells.
Q 02In which 1665 book did the word "cell" first appear, describing pores in a sliver of cork?
Micrographia
The book was the first major work on microscopy and became a bestseller; Samuel Pepys stayed up until two in the morning reading it.
Q 03The word "cell" comes from the Latin cellula. What does it mean?
Small room
The same root gives us the prison cell and the monk's cell, which is exactly the image Hooke had in mind.
Q 04Roughly how many cells make up a typical adult human body?
30 trillion
The estimate is around 36 trillion for an adult male and 28 trillion for a female, and most of them are red blood cells.
Q 05About how many different cell types are there in the human body?
200
Neurons, hepatocytes, red blood cells and their relatives all trace back to a single fertilised egg.
Q 06Which botanist developed cell theory with Theodor Schwann in 1839?
Matthias Schleiden
Schleiden worked on plants and Schwann on animals; the story goes that they compared notes over dinner and realised the two kingdoms were built the same way.
Q 07Rudolf Virchow's 1855 tenet "Omnis cellula e cellula" translates as what?
Every cell comes from a cell
The tenet killed off the idea of spontaneous generation at the cellular level and completed what is now called classical cell theory.
Q 08Which organelle is nicknamed the "powerhouse of the cell"?
Mitochondrion
It earns the name by using aerobic respiration to make ATP, and it comes with its own small genome inherited from the mother.
Q 09Philip Siekevitz popularised "powerhouse of the cell" in a 1957 article in which magazine?
Scientific American
The article carried the phrase as its title, and it has been on every biology worksheet since.
Q 10A mature red blood cell has no mitochondria at all. Roughly how many can a single liver cell contain?
More than 2,000
The liver's energy demands are enormous, while a red blood cell only needs to carry hemoglobin and can get by on glycolysis alone.
Q 11Which of these has no nucleus when mature and is packed with hemoglobin?
Red blood cell
Ejecting the nucleus frees up space for hemoglobin and gives the cell its flexible biconcave shape for squeezing through capillaries.
Q 12Approximately how many new erythrocytes does an adult human produce every second?
2.4 million
They are made in the bone marrow, and after their run of roughly four months they are recycled by the spleen and liver.
Q 13How long does a human erythrocyte typically circulate before it is retired?
About 120 days
The cell has no nucleus, so it cannot repair itself; wear and tear eventually gets it flagged for removal.
Q 21Which Italian physician identified the cell's protein-packaging 'apparatus' in 1898?
Camillo Golgi
For decades some biologists insisted the structure was an artefact of his silver stain; the electron microscope finally proved it was real.
Q 22The stacked, flattened membrane disks that make up the cell's protein-dispatch organelle are called what?
Cisternae
They are sorted into cis, medial and trans compartments, so proteins move through the stack like parcels along a conveyor.
Q 23Which organelle carries out photosynthesis in plant and algal cells?
Chloroplast
A wheat leaf cell can hold up to 100 of them, and each carries its own DNA left over from a captured cyanobacterium.
Q 14Which Delft draper first observed bacteria and sperm cells using tiny single-lens microscopes he made himself?
Antonie van Leeuwenhoek
His best surviving lenses magnify about 275 times, better than the compound microscopes of his day, and he wrote some 560 letters describing what he saw.
Q 15What did the Dutch microscopist who first saw bacteria call the tiny swimming creatures?
Animalcules
He argued in a 1676 letter to the Royal Society that because they moved on their own they must be alive.
Q 16Which organelle builds proteins by translating the code carried by messenger RNA?
Ribosome
It is mostly made of RNA rather than protein, which is one reason many think RNA came before DNA in the history of life.
Q 17Which Romanian-American cell biologist first observed ribosomes in the mid-1950s?
George Palade
For a while they were simply called Palade granules; he shared the 1974 Nobel Prize for mapping the cell's inner structure.
Q 18Prokaryotic ribosomes are 70S. What size are the ribosomes floating in a eukaryotic cell's cytosol?
80S
The S stands for Svedberg units, a measure of how fast a particle settles in a centrifuge, which is why 40S and 60S subunits add up to 80S rather than 100S.
Q 19Which Belgian scientist discovered lysosomes and shared the 1974 Nobel in Medicine?
Christian de Duve
He found them almost by accident while chasing an enzyme that kept turning up in the wrong fraction of his centrifuged liver cells.
Q 20The digestive enzymes inside a lysosome work best at roughly what pH?
pH 4.5–5.0
The acidity is a safety feature: if the enzymes leak into the neutral cytosol they mostly stop working instead of digesting the cell.
Q 24The green pigment in a plant cell is held in stacks of disk-like sacs called what?
Thylakoids
A stack of them is a granum, and the fluid around the stacks, the stroma, is where sugar is actually assembled.
Q 25Lynn Margulis's 1967 paper argued that mitochondria and chloroplasts were once what?
Free-living bacteria
The paper was rejected by more than a dozen journals before it was printed, and the endosymbiotic theory is now textbook orthodoxy.
Q 26Who coined the term "mitosis" in 1882, from the Greek word for a thread?
Walther Flemming
The threads were the chromosomes he watched condensing under his aniline dyes; the word chromatin is his too.
Q 27During which stage of mitosis do chromosomes line up along the middle of the cell?
Metaphase
The imaginary line they gather on is the metaphase plate; the checkpoint here makes sure every chromosome is attached before the cell pulls them apart.
Q 28What is the splitting of the cytoplasm into two daughter cells after nuclear division called?
Cytokinesis
Strictly speaking it is not a phase of mitosis at all; animal cells pinch in two with a contractile ring while plant cells build a new wall down the middle.
Q 29After both rounds of meiosis, how many haploid cells has a single starting cell produced?
Four
In human females only one of the four becomes a usable egg; the other three shrivel into polar bodies.
Q 30Who first described meiosis in 1876, working with sea urchin eggs?
Oscar Hertwig
The word itself came later: J.B. Farmer and J.E.S. Moore introduced it in 1905, spelling it "maiosis".