Cell Trivia
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This cell trivia quiz has 120 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.
30 of 120 questions with answers and explanations. Play the quiz
Q 01Who coined the term "cell" in 1665 after examining thin slices of cork under a microscope?
Robert Hooke
Robert Hooke never knew what he had named: all his cork showed was the empty walls the cells had left behind, and he had no idea such boxes were the basic unit of every living thing.
Q 02Which 1665 book first used the word "cell" in biology, for the pores in a sliver of cork?
Micrographia
Micrographia was a best-seller in its day: the diarist Samuel Pepys sat up until two in the morning with it and called it the most ingenious book he had ever read.
Q 03The word "cell" comes from the Latin cella, which means what?
Small room
Small room: the man who named the cell was looking at a slice of cork, and its tiny pores are said to have reminded him of the rooms monks lived in.
Q 04Roughly how many cells make up a typical adult human body?
30 trillion
30 trillion comes from a 2016 recount that also overturned a textbook claim: the bacteria living in you do not outnumber your own cells ten to one but roughly match them, at just under 40 trillion.
Q 05Your nerve cells and liver cells carry the same DNA, so what makes them differ?
Which genes are switched on
Which genes are switched on: nearly every cell keeps the full genome and reads only part of it, which is why Dolly the sheep could be cloned in 1996 from a single adult udder cell.
Q 06Which botanist shares credit with Theodor Schwann for founding cell theory in the late 1830s?
Matthias Schleiden
Matthias Schleiden brought up the nucleus of plant cells over dinner in 1837; Schwann realised he had seen the same structure in animal tissue, and the two checked it together under a microscope.
Q 07Rudolf Virchow's 1855 maxim that every cell comes from another cell rejected which old idea?
Spontaneous generation
Spontaneous generation, the belief that life can arise from lifeless matter, was the target, yet the insight was borrowed: Robert Remak had shown that cells come from dividing cells three years earlier, and Virchow gave him no credit.
Q 08Which organelle is nicknamed the "powerhouse of the cell"?
Mitochondrion
Mitochondrion: it carries a small genome of its own, 37 genes handed down from the mother, which is why geneticists use it to trace a maternal line far back in time.
Q 09The nickname "powerhouse of the cell" was the headline of a 1957 article in which magazine?
Scientific American
Scientific American ran it in July 1957, over an article by Philip Siekevitz, when exactly how the organelle makes its energy was still unknown: Peter Mitchell's now-accepted answer came only in 1961.
Q 10Which human cell throws out its own nucleus as it matures?
A red blood cell
A red blood cell sheds its nucleus and its energy-producing organelles too, so the cell that carries your oxygen cannot use any of it and lives by fermenting sugar instead.
Q 11Which tiny blood components clump together to plug a wound and start a clot?
Platelets
Platelets are not whole cells at all: they are scraps of cytoplasm pinched off giant cells called megakaryocytes, so they have no nucleus of their own.
Q 12A healthy adult makes millions of new red blood cells every second, in which tissue?
Bone marrow
Bone marrow takes its orders from the kidneys: when they sense too little oxygen in the blood they release the hormone EPO, which tells the marrow to speed up.
Q 13About how long does a human red blood cell circulate before the body retires it?
About 120 days
About 120 days is all it gets: by then its membrane has aged, and macrophages in the spleen and liver swallow the worn-out cell and recycle its parts.
Q 21Which Italian physician identified the cell's protein-packaging 'apparatus' in 1898?
Camillo Golgi
Camillo Golgi's find was written off by some as a mere artefact of his metal stain, and it took the electron microscope, in the 1950s, to prove the structure was real.
Q 22The stacked, flattened membrane disks that make up the cell's protein-dispatch organelle are called what?
Cisternae
Cisternae work like a production line: a protein enters at the cis face, is trimmed and tagged as it crosses the stack, and leaves from the trans face packed in a vesicle.
Q 23Which organelle carries out photosynthesis in plant and algal cells?
Chloroplast
Q 14Which Delft draper first observed bacteria through tiny single-lens microscopes he made himself?
Antonie van Leeuwenhoek
Antonie van Leeuwenhoek made more than 500 lenses in his lifetime and kept his best methods secret, so exactly how he made them stayed a mystery for centuries.
Q 15What name did 17th-century science give the tiny swimming creatures seen by the first man to observe bacteria?
Animalcules
Animalcules, Latin for "little animals", caused such a stir when his letter was read to London's Royal Society that it asked him to reveal his methods so that others could confirm them; he declined.
Q 16A ribosome builds a protein by reading the code carried on which molecule?
Messenger RNA
Messenger RNA is a working copy of a gene, read three letters at a time; the COVID-19 mRNA vaccines exploit this by handing our cells the instructions for one viral protein.
Q 17Which Romanian-American cell biologist first observed ribosomes in the mid-1950s?
George Palade
George Palade spotted them as dense specks in electron-microscope pictures of cells, and for a few years they were known simply as Palade granules, until the word ribosome replaced his name.
Q 18A ribosome's 80S size measures how fast it does what?
Sinks in a centrifuge
Sinks in a centrifuge: the rate depends on shape as well as mass, so Svedberg values do not simply add, which is why a 40S and a 60S subunit make an 80S ribosome, not a 100S one.
Q 19Which Belgian scientist discovered lysosomes and shared the 1974 Nobel in Medicine?
Christian de Duve
Christian de Duve set out to learn how insulin works, but a chance oddity in a liver enzyme sidetracked him into finding the lysosome; by his own account he never did solve insulin.
Q 20A lysosome's digestive enzymes work only in which conditions, shutting down if they leak into the rest of the cell?
Acidic
Acidic conditions, around pH 5, are kept up by proton pumps in the lysosome's membrane; the rest of the cell sits near a neutral pH 7.2, so enzymes that escape mostly stall instead of digesting it.
Chloroplast is a name for something surprisingly mobile: in dim light they spread across the cell to catch more of it, and in harsh sun they retreat to the side walls to avoid light damage.
Q 24The green pigment in a plant cell is held in stacks of disk-like sacs called what?
Thylakoids
Thylakoids stack like coins into a granum, yet they only capture the light: the sugar itself is assembled in the fluid around the stacks, the stroma.
Q 25Lynn Margulis's 1967 paper argued that mitochondria and chloroplasts were once what?
Free-living bacteria
Free-living bacteria swallowed by bigger cells, she argued: the paper was reportedly turned down by more than a dozen journals before one printed it, and the idea went on to become textbook biology.
Q 26Walther Flemming named mitosis in 1882 after the Greek word for what, describing how chromosomes looked under his dyes?
Thread
Thread is what he saw: newly invented aniline dyes picked out stringy material in the nucleus that shortened and split in two, and the threads were only later renamed chromosomes.
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
Cytokinesis is, strictly, not a phase of mitosis at all: animal cells pinch in two with a contractile ring, while plant cells build a new wall, the cell plate, down the middle.
Q 29After both rounds of meiosis, how many haploid cells has a single starting cell produced?
Four
Four, but in women only one of them becomes an egg: it keeps nearly all the cytoplasm, while the others are tiny polar bodies that soon break down.
Q 30During meiosis, paired chromosomes swap matching stretches of DNA in a gene-shuffling step known as what?
Crossing over
Crossing over means each chromosome a parent passes on is a fresh patchwork of the pair that parent inherited, which helps explain why no two eggs or sperm carry the same mix.