Beyond the answers - interesting background to this quiz

Three bones, one odd intruder

The middle ear contains the smallest bones in the human body: the malleus (hammer), incus (anvil) and stapes (stirrup). Together they are called the auditory ossicles, and they transmit vibrations from the eardrum to the inner ear. The stapes is the tiniest bone of all, yet it plays a crucial role in hearing. A "saddle" belongs to a horse, not to your ear - though the word does appear in anatomy, as in the saddle joint at the base of the thumb.

A mural that barely survived

Leonardo da Vinci painted "The Last Supper" on a refectory wall in Milan around 1495-1498. Rather than using true fresco, he applied tempera and oil directly onto dry plaster, which let him work slowly and rework details. The experiment backfired: the paint began flaking within decades, and the mural has been restored repeatedly. Even in its damaged state, it remains one of the most studied images in Western art.

The Rock at Europe's crossroads

Gibraltar sits at the southern tip of the Iberian Peninsula, guarding the narrow strait between the Atlantic and the Mediterranean. Spain ceded it to Britain in 1713 under the Treaty of Utrecht, and it has been a British Overseas Territory ever since. Spain still claims sovereignty, and the question of belonging has been politically sensitive for centuries. Residents voted overwhelmingly to remain British in referendums held in 1967 and 2002.

The river that moves the most water

Discharge is the volume of water a river carries past a given point over time, and by that measure the Amazon dwarfs every other river on Earth. Fed by enormous rainfall across its basin, it releases roughly 200,000 cubic metres per second into the Atlantic - several times the flow of the Congo or the Ganges. Its plume of fresh water can be detected far out at sea.

A long road to the ballot box

The Nineteenth Amendment to the United States Constitution, ratified in 1920, barred denying the vote on the basis of sex. It came after decades of campaigning by suffragists, and it did not guarantee the vote for all women in practice - many Black women in the South remained disenfranchised by discriminatory state laws until the Voting Rights Act of 1965.