Blood Trivia
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This blood trivia quiz has 99 free questions with answers and covers the science and the stories of the roughly five litres flowing through you. It starts with the basics (what plasma is, how long a red blood cell lives, why blood is red, what platelets do, what the hematocrit measures) and moves through blood types and the discoveries of Karl Landsteiner, the grisly early history of transfusion, the first blood bank, and the diseases from anaemia and sickle cell to the 'royal disease' haemophilia. It also wanders into the natural world and history: the horseshoe crab's blue blood, the skinks with green blood, vampire bats and leeches, bloodletting and the barber's pole, William Harvey's discovery of circulation, and how blood pressure came to be measured. About a third of the questions are easy enough for a school biology class; the rest are for nurses, medics and hardcore quizzers. Every answer has been checked against Wikipedia's articles on blood, haematology and their history, and each question links to the page that confirms it.
30 of 99 questions with answers and explanations. Play the quiz
Q 01Roughly how much blood does the average adult have?
About 5 litres
About 5 litres, or some eleven pints, circulate in a typical adult, which is why a donor can spare the single pint taken at a blood drive: it is less than a tenth of the supply.
Q 02What is the straw-yellow liquid that makes up about 55% of blood?
Plasma
Plasma carries the blood cells, hormones and nutrients around the body; frozen after donation it keeps for a year, against about six weeks for red cells, so hospitals can stockpile it.
Q 03Which iron-containing protein in red blood cells carries oxygen?
Hemoglobin
Hemoglobin comes in a fetal version that grips oxygen more tightly than the adult kind, which is how an unborn baby draws oxygen out of its mother's blood across the placenta.
Q 04A blood clot blocking an artery in the brain causes which medical emergency?
A stroke
A stroke caused by a clot is the common kind, about 87% of cases, with a burst vessel behind the rest; clot-dissolving drugs can help, but only if given within a few hours.
Q 05Roughly how long does a human red blood cell circulate before it is recycled?
100-120 days
100-120 days is the typical lifespan; worn-out red cells are then swallowed by scavenger cells called macrophages, and their iron is salvaged to build new ones.
Q 06Unlike those of birds, reptiles and fish, mature mammalian red blood cells lack what?
A nucleus
A nucleus is pushed out as a mammal's red cells mature, which frees space for more oxygen-carrying protein; birds, reptiles and fish keep theirs.
Q 07What is the term for the proportion of blood volume occupied by red blood cells, normally about 45%?
Hematocrit
Hematocrit, also called packed cell volume, is read by spinning a sample in a centrifuge; values run higher in men than in women and rise at high altitude.
Q 08Platelets are not true cells but fragments of the cytoplasm of which large bone-marrow cells?
Megakaryocytes
Megakaryocytes, giant polyploid cells in the marrow, each shed thousands of platelets from their cytoplasm; the resulting anucleate fragments are unique to mammals.
Q 09On the pH scale, healthy human blood is kept within a narrow band that makes it what?
Slightly alkaline
Slightly alkaline: blood is held between pH 7.35 and 7.45, just above neutral, so even 'acidosis', the name for a fall below 7.35, describes blood that is still on the alkaline side of 7.
Q 10Approximately how many blood cells does human bone marrow produce every day?
500 billion
500 billion a day is the usual estimate, roughly 2 million red cells every second, because blood cells are short-lived and the marrow has to replace them as fast as they wear out.
Q 11Which Austrian physician discovered the ABO blood groups in 1901?
Karl Landsteiner
Karl Landsteiner, working in Vienna, sorted blood into three groups in 1901 and labelled them A, B and C; his students found the fourth, AB, a year later, and C became today's O.
Q 12The Rh blood factor was named after which animal, in whose red cells a similar antigen was found?
Rhesus macaque
Rhesus macaque red cells, injected into rabbits, produced the serum first used to detect the factor; the human antigen later proved to be a different one, but the name stuck.
Q 13Which blood type is known as the 'universal donor' for red cell transfusions?
O RhD-negative
Q 21In which Stephen King novel is a bullied schoolgirl drenched in pig's blood at her prom?
Carrie
Carrie was King's first published novel, and it nearly wasn't written: he threw the opening pages in the trash, and his wife Tabitha fished them out and talked him into carrying on.
Q 22Carriers of the sickle cell gene are partly protected against which disease?
Malaria
Malaria parasites fare worse in red cells carrying one sickle gene, a protective effect Anthony Allison demonstrated in 1954; the trait is commonest where malaria has been endemic.
Q 23Leukemia is a cancer of which type of blood cell?
White cells
White cells multiply out of control in leukemia, and that is how it got its name: Rudolf Virchow, who described the disease in the 1840s and named it, called it 'white blood'.
O RhD-negative red cells carry neither A, B nor RhD antigens, so they can be given to almost anyone; hospitals reserve the supply for emergencies and O-negative patients.
Q 14Which blood type is called the 'universal recipient'?
AB RhD-positive
AB RhD-positive people carry A, B and RhD antigens on their red cells, so their serum holds no antibodies against any of them and accepts every ABO and Rh type.
Q 15Jean-Baptiste Denys, who performed the first animal-to-human transfusion in 1667, was physician to which king?
Louis XIV of France
Louis XIV of France employed Denys as a physician; Denys transfused lamb's blood into a feverish boy in June 1667, and after a later patient died the practice was banned in France.
Q 16Which Shakespeare character sleepwalks while trying to scrub an imaginary spot of blood from her hands?
Lady Macbeth
Lady Macbeth cries 'Out, damned spot!' as she rubs at blood only she can see, while a doctor and her gentlewoman watch and hear her give away the murders of Duncan and Banquo.
Q 17Bernard Fantus opened one of America's first hospital blood banks in 1937 at Cook County Hospital in which city?
Chicago
Chicago's Cook County Hospital began keeping refrigerated donor blood ready for use, and Fantus, its director of therapeutics, came up with the name 'blood bank' for the store.
Q 18Which physician described the circulation of the blood in his 1628 treatise De Motu Cordis?
William Harvey
William Harvey won the argument with arithmetic: using deliberately low estimates of what the heart pumps at each beat, he showed it moves far more blood in half an hour than the body could make afresh.
Q 19Haemophilia is 'the royal disease' because which monarch passed the mutation to royal families across Europe?
Queen Victoria
Queen Victoria carried the mutation: her son Leopold had haemophilia, and through daughters Alice and Beatrice it reached the royal houses of Russia, Spain and Germany, including Tsarevich Alexei.
Q 20Haemophilia strikes mostly men because its gene sits on which chromosome?
X chromosome
The X chromosome carries the genes for clotting factors VIII and IX; men have only one X, so a single faulty copy causes the disease, while women with a healthy second copy are usually just carriers.
Q 24Horseshoe crab blood is bright blue because it carries oxygen with which copper-based protein?
Hemocyanin
Hemocyanin carries oxygen using copper atoms, turning blue when oxygenated; horseshoe crab blood is also harvested for Limulus amebocyte lysate, a clotting agent that detects bacterial endotoxins.
Q 25Skinks of the genus Prasinohaema have green blood because of a build-up of which waste pigment?
Biliverdin
Biliverdin, a green bile pigment, saturates these New Guinea skinks, tinting their blood, muscles and bones green, and nobody is yet sure what advantage, if any, it gives them.
Q 26Vampire bats, the only mammals that feed solely on blood, live wild in which part of the world?
The Americas
The Americas, from Mexico down through South America, are home to all three vampire bat species, each in its own genus; an anticoagulant in their saliva keeps the wound flowing while they lap.
Q 27The medicinal leech secretes which peptide to stop its host's blood clotting while it feeds?
Hirudin
Hirudin blocks the clotting enzyme thrombin, which is why surgeons still use leeches in microsurgery, and why chemists modelled the anticoagulant drug bivalirudin on it.
Q 28The red-and-white barber's pole is a relic of which medical practice once performed by barber-surgeons?
Bloodletting
Bloodletting was a barber-surgeon's trade: the pole's red recalls blood and the white the bandages, and the practice rested on the ancient idea of balancing the humours.
Q 29Which US president asked to be bled for a throat infection, hours before his death in 1799?
George Washington
George Washington had his overseer open a vein before the doctors arrived; they bled him three more times that day, about five pints in all, and he died that night at Mount Vernon.
Q 30What does the top, systolic, figure in a blood pressure reading measure?
The peak during a heartbeat
The peak during a heartbeat is the systolic pressure: the cuff is pumped up until it squeezes the artery shut, then let down slowly, and the first tapping sound heard marks the top figure.