Biochemistry
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50 free Biochemistry trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Biochemistry is the chemistry of living things: how a body turns a meal into movement, why hair is tough and a cut stops bleeding, and what goes wrong at the level of single molecules in an inherited illness. The same handful of molecule types runs every cell of every organism, which is why a discovery made in a microbe so often ends up explaining something about people. This quiz covers the ground a first biochemistry course does. There are questions on proteins and the amino acids they are built from, on enzymes and how they do their work, on carbohydrates, lipids and cell membranes, and on fuel metabolism, the pathways that pull energy out of food. The people are here too: the Nobel winners, the lucky accidents and the experiments that started the field. The first questions are for anyone curious about what food, muscles and genes are made of. The later ones are closer to what a biology or pre-med student meets before an exam. Each answer has a short explanation, so even a miss leaves you knowing something new.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Which hormone was first injected into a patient in 1922, when Toronto doctors treated a dying 14-year-old boy?
Insulin
Insulin had been isolated from dog pancreas only months earlier by Banting and Best. The extract given to the boy was so impure that he had a severe allergic reaction.
Q 02Which protein, the most abundant in mammals, turns into gelatin when animal bones and hides are boiled?
Collagen
Collagen makes up 25% to 35% of all the protein in a mammal's body. It often survives in ancient bones, so it may be one of the most abundant proteins in the fossil record too.
Q 03Which tough protein forms human hair and fingernails as well as the horns of cattle and rhinos?
Keratin
Keratin is rich in sulfur, which is why burning hair smells so pungent. The same protein family builds feathers, hooves, claws and the slime threads of hagfish.
Q 04Which stimulant fights drowsiness by blocking brain receptors for adenosine, which builds up during waking hours?
Caffeine
Caffeine sits in the adenosine receptor without switching it on, so the drowsiness signal never arrives. Heavy use makes the body produce more of those receptors.
Q 05Which sugar in milk are around 65% of adults worldwide unable to absorb fully?
Lactose
Lactose is digested by an enzyme that most people make less of after infancy. Struggling with milk as an adult is the ancestral human state, and tolerance evolved later among dairy farmers.
Q 06Which iron-containing protein makes up about 96% of a red blood cell's dry weight and carries oxygen around the body?
Hemoglobin
Hemoglobin lets blood carry about seventy times more oxygen than could dissolve in plasma alone. Max Perutz worked out its molecular structure in 1959.
Q 07Which margarine ingredient, formed when vegetable oil is partially hydrogenated, did the US FDA rule unsafe in 2015?
Trans fats
Trans fats occur naturally in small amounts in meat and dairy, but the food industry had been making them in bulk since the early 1900s, first for margarine and then for snacks and baked goods.
Q 08Which nutrient can most animals make for themselves, although humans, guinea pigs and most bats must get it from food?
Vitamin C
Vitamin C is out of human reach because mutations have broken a gene for one of the enzymes that make it. A rat simply builds its own supply from sugar.
Q 09Which chemist's PhD student took Photo 51, the 1952 X-ray image that proved critical evidence for the structure of DNA?
Rosalind Franklin
Rosalind Franklin had not given permission when Maurice Wilkins showed the image to Watson. It was the 51st diffraction photo her student Raymond Gosling had taken.
Q 10Which substance, the most abundant organic polymer on Earth, makes up about 90% of cotton fibre and nearly half of wood?
Cellulose
Cellulose passes through humans undigested, as dietary fibre. Cows and termites can live on it only because microbes in their guts break it down for them.
Q 11Which structures in human cells carry their own DNA, which is normally inherited only from the mother?
Mitochondria
Mitochondria in a father's sperm are usually destroyed by the egg after fertilization. That is why genealogists can use their DNA to trace a maternal line far back in time.
Q 12Which carbohydrate, the most common in the human diet, turns an intense blue-black on contact with iodine solution?
Starch
Starch traps iodine inside the coils of its long chains, and that shifts the colour. Plants make it to store energy, which is why potatoes, rice and wheat are full of it.
Q 13Which waxy lipid, first identified in gallstones in 1769, is the raw material for the body's steroid hormones?
Cholesterol
Q 21Which element, first isolated in 1669 by an alchemist boiling down urine, is part of the framework of DNA?
Phosphorus
Phosphorus glowed in the dark when Hennig Brand first made it, while hunting for the philosopher's stone. It is the first element whose discoverer and date of discovery are on record.
Q 22Which French scientist first showed that molecules can be left- or right-handed, using tartrate crystals in 1848?
Louis Pasteur
Louis Pasteur noticed that half the crystals were mirror images of the other half. He worked out that a lopsided arrangement inside each molecule was what twisted light one way or the other.
Q 23Which amino acid, wrongly blamed for drowsiness after a turkey dinner, does the body turn into serotonin?
Tryptophan
Cholesterol is made by the body's own cells, so the body does not rely on food for its supply. Other animals make it too, which is why all animal-based foods contain some.
Q 14Which yellow-green liquid, made by the liver and stored in the gallbladder, helps break up the fat in food?
Bile
Bile acts as a surfactant, spreading fat into tiny droplets much as washing-up liquid does. Its colour comes from two pigments, one orange-yellow and one green.
Q 15Which compound, produced in muscles during exertion, also gives yogurt and kefir their sour flavour?
Lactic acid
Lactic acid was first isolated in 1780 by the Swedish chemist Carl Wilhelm Scheele. Far from being mere waste, it is burned as fuel by the heart, the brain and resting muscle.
Q 16Which Y-shaped proteins does the immune system use to identify and neutralize invaders such as bacteria and viruses?
Antibodies
Antibodies go on being made long after an infection is over. Some of the plasma cells that secrete them can potentially live for a person's whole lifetime.
Q 17Which elastic network of proteins forms when wheat flour is wetted and kneaded, giving bread dough its stretch?
Gluten
Gluten is built from two kinds of protein in the grain, gliadin and glutenin, linking up. Around 1–2% of people have celiac disease and cannot tolerate it.
Q 18Which process, in which water crosses a membrane toward the more concentrated side, is how table salt kills slugs?
Osmosis
Osmosis is also why a potato slice shrinks in salty water. The stronger the salt solution, the more size and weight the slice loses.
Q 19In which US national park was the bacterium found whose heat-proof enzyme, Taq polymerase, makes PCR tests possible?
Yellowstone
Yellowstone received no share of the profits made from the enzyme. Thomas Brock and Hudson Freeze had isolated the microbe from the park's Mushroom Spring in the 1960s.
Q 20Which sea animal first yielded green fluorescent protein, the glowing tag behind the 2008 Nobel Prize in Chemistry?
Jellyfish
Jellyfish of the species Aequorea victoria carry the protein in small granules around the rim of the bell. Nobody knows what purpose the glow serves.
Tryptophan is no more plentiful in turkey than in other poultry. The carbohydrates served alongside the bird are a likelier cause of the slump after a big meal.
Q 24Which amino acid did Kikunae Ikeda isolate from kelp broth in 1908 as the source of the savoury taste umami?
Glutamate
Glutamate also adds to the flavour of meat and tomatoes, as Ikeda went on to confirm. His search began with a bowl of soup that tasted better than usual because of the kombu in it.
Q 25Which infectious agent, a misfolded protein containing no DNA or RNA, is the hypothesized cause of mad cow disease?
Prion
Prion is a word Stanley Prusiner built from 'protein' and 'infection'. He won the 1997 Nobel Prize in Physiology or Medicine for his research into them.
Q 26Which two-object analogy sums up Emil Fischer's 1894 idea that an enzyme and its substrate have matching shapes?
Lock and key
Lock and key was revised in 1958 by Daniel Koshland, who pointed out that enzymes are flexible. In his version the enzyme is reshaped as the substrate binds to it.
Q 27Which enzyme in human saliva can make rice and potatoes taste sweet as they are chewed?
Amylase
Amylase begins digestion in the mouth, cutting long carbohydrate chains down into sugar. The pancreas makes it as well as the salivary glands.
Q 28Which solvent, a main ingredient of many nail polish removers, gives the breath a fruity smell during ketosis?
Acetone
Acetone forms when the liver breaks down fat rapidly, as in a long fast or a very low-carb diet. It is so volatile that it passes from the blood into the air a person breathes out.
Q 29Which popular dietary supplement, named from the Greek word for meat, helps muscle and brain cells recycle ATP?
Creatine
Creatine was first isolated from skeletal muscle in 1832 by the French chemist Michel Eugène Chevreul. Products built around it for strength training did not go on sale until 1993.
Q 30Which DeepMind AI program, whose developers shared the 2024 Nobel Prize in Chemistry, predicts protein structures?
AlphaFold
AlphaFold learned its craft from more than 170,000 known protein structures held in a public database. Demis Hassabis and John Jumper took half of the prize for it.