Proteins
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50 free Proteins trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Proteins do most of the work of being alive. They speed up reactions, carry oxygen, fight infection, move muscles and hold skin, hair and bone together, and every one of them is built from the same small kit of amino acids. This quiz covers what proteins are made of and how their shape decides what they do, how cells read genes to build them, what happens when they misfold, and where protein comes from in the diet. It also visits the lab: the people who named, sequenced and mapped proteins, and the tools researchers use today. The opening questions suit GCSE and high-school biology revision, and the later ones reach into A-level, AP and introductory biochemistry. Every answer comes with a short explanation, so a wrong guess still teaches something.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Rhinoceros horn is made of which protein, the same material found in human hair and fingernails?
Keratin
Keratin also builds feathers, claws, hooves and the outer layer of skin. Rhino horn has no proven health benefits, whatever the poaching trade claims.
Q 02Miraculin, a protein from a West African berry, binds to taste receptors and makes sour foods taste how?
Sweet
Sweet is how lemons and limes taste for an hour or two after miraculin coats the tongue. The protein has no sugary taste of its own.
Q 03Green fluorescent protein, which earned a 2008 Nobel Prize, was first isolated from which glowing sea animal?
Jellyfish
Jellyfish of the species Aequorea victoria supplied the first GFP. Scientists now fuse its gene to other genes to watch proteins light up inside living cells.
Q 04Which infectious misfolded proteins, containing no DNA or RNA, cause mad cow disease in cattle?
Prions
Prions spread by forcing normal copies of the same protein to misfold. Stanley Prusiner coined the name by blending protein and infection.
Q 05Which structural protein, the most abundant in mammals, takes its name from the Greek word for glue?
Collagen
Collagen makes up 25% to 35% of the protein in a mammal's body. Doctors use it in artificial skin to help severe burns heal.
Q 06Octopus blood is blue because the protein hemocyanin carries oxygen using which metal instead of iron?
Copper
Copper atoms in hemocyanin turn blue when they bind oxygen and go colourless when they let it go. The protein was first found in the common octopus in 1878.
Q 07Which amino acid is wrongly blamed for making people sleepy after a Thanksgiving turkey dinner?
Tryptophan
Tryptophan is no more plentiful in turkey than in other poultry. The slump after a feast may come from the other foods eaten alongside the bird.
Q 08Antarctic notothenioid fish survive in subzero seawater because proteins in their blood act as what?
Antifreeze
Antifreeze proteins bind to small ice crystals and stop them growing. Antarctic fish and northern cod evolved theirs separately.
Q 09Which oxygen-binding protein in muscle is the pigment responsible for the colour of red meat?
Myoglobin
Myoglobin turns brown as its iron changes state in cooking, which is why a well-done steak loses its red. Cured ham stays pink because nitrites lock the pigment.
Q 10Which hormone became the first protein to be fully sequenced, work that won Frederick Sanger a Nobel Prize?
Insulin
Insulin's sequence proved that a protein has one exact order of amino acids. Before the human form could be made in bulk, diabetics relied on insulin taken from pigs.
Q 11Which iron-containing protein packs red blood cells and ferries oxygen from the lungs around the body?
Hemoglobin
Hemoglobin was the first protein to have its molecular mass worked out, calculated from the weight of the iron it carries.
Q 12Which tiny cell structure, first observed by George Palade in 1955, links amino acids into protein chains?
Ribosome
Ribosomes are themselves part protein: each has a small and a large subunit built from RNA and many proteins.
Q 13Which Y-shaped proteins does the immune system use to identify and neutralise bacteria and viruses?
Antibodies
Antibodies are also known as immunoglobulins. The tip of each arm of the Y works like a lock that fits one particular target.
Q 21Which chemical link joins one amino acid to the next, releasing a molecule of water as it forms?
Peptide bond
Peptide bond formation is a condensation reaction. Adding the water back, a step called hydrolysis, breaks the chain apart again.
Q 22What term describes the nine amino acids that the human body cannot make and must get from food?
Essential
Essential amino acids were pinned down by William Cumming Rose, who fed volunteers diets of purified amino acids and watched what happened when one was left out.
Q 23Which stomach enzyme, switched on by hydrochloric acid, begins breaking down the proteins in a meal?
Pepsin
Pepsin was one of the first enzymes ever discovered, by Theodor Schwann in 1836. He named it after the Greek word for digestion.
Q 14What name is given to the unfolding of proteins that turns a clear raw egg white solid when cooked?
Denaturation
Denaturation is not only caused by heat. Pouring egg whites into a beaker of acetone turns them solid too.
Q 15Which elastic network of wheat proteins lets bread dough stretch, rise and keep a chewy texture?
Gluten
Gluten forms when two wheat proteins, gliadin and glutenin, are wetted and kneaded together. It accounts for 75–85% of the protein in bread wheat.
Q 16Which protein family, named from the Latin for cheese, makes up about 80% of the protein in cow's milk?
Casein
Casein clumps into curd when milk is soured, the first step towards cheese. Human milk contains a much smaller share of it than cow's milk.
Q 17Which liquid byproduct of cheese-making is processed into a protein supplement popular for building muscle?
Whey
Whey is the liquid left behind when milk coagulates. Ricotta and Norwegian brunost are cheeses made from it.
Q 18Food labs estimate protein content by measuring which element, found in every amino acid but not in fat?
Nitrogen
Nitrogen makes up about 16% of an average protein, so food labels simply multiply the amount measured by 6.25.
Q 19Gram for gram, protein supplies about 4 kilocalories, the same food energy as which other nutrient?
Carbohydrate
Carbohydrate and protein both yield about 17 kilojoules per gram, less than half the energy packed into the same weight of fat.
Q 20Which giant muscle protein has a full chemical name of 189,819 letters, sometimes called the longest word in English?
Titin
Titin takes its name from the Titans of Greek myth. A single molecule strings together around 34,350 amino acids and acts as a spring inside muscle.
Q 24Which childhood disease of severe protein deficiency is marked by swollen feet and a bloated belly?
Kwashiorkor
Kwashiorkor comes from the Ga language of coastal Ghana and means roughly the sickness the baby gets when the new baby comes. It struck toddlers weaned early to make way for a younger sibling.
Q 25Which protein-rich food is made by coagulating soy milk and pressing the curds into solid white blocks?
Tofu
Tofu making was first recorded in China during the Han dynasty. Zen Buddhist monks later introduced it to Japan.
Q 26Lentils, peas, beans and peanuts are protein-rich seeds from which family of plants?
Legumes
Legumes house bacteria in their roots that enrich the soil, so farmers rotate them with other crops. The family's formal name is Fabaceae.
Q 27Fibroin, a tough protein made by larvae of the moth Bombyx mori, forms the filaments of which fabric?
Silk
Silk in its raw state is two fibroin filaments coated in a second, glue-like protein called sericin. Fibroin's tightly packed sheets give the thread its strength.
Q 28Which bacterial protein, considered the deadliest known natural substance, is injected in tiny doses to smooth wrinkles?
Botulinum toxin
Botulinum toxin relaxes the facial muscles it is injected into, so the skin above them smooths out. The full effect typically shows about a week later.
Q 29Which lethal protein from castor beans killed dissident Georgi Markov, shot with a pellet from a modified umbrella?
Ricin
Ricin does not dissolve in oil, so little of it ends up in the castor oil pressed from the same seeds. The leftover seed cake stays toxic unless heat-treated.
Q 30Clumps of amyloid beta and tangles of tau protein in the brain are the hallmarks of which brain condition?
Alzheimer's disease
Alzheimer's disease is defined by those two abnormal proteins. One builds up as plaques outside nerve cells and the other as tangles inside them.