Beyond the answers - interesting background to this quiz

A cheese with a protected pedigree

Mozzarella is one of Italy's most famous exports, and the traditional fresh version, mozzarella di bufala campana, is made from the milk of water buffalo. It holds Protected Designation of Origin status within the European Union, meaning it can only be produced in specific parts of Italy. The milder, cow's-milk version, fior di latte, is what most of us find on supermarket shelves.

Orwell's warnings that outlived him

George Orwell published "1984" in 1949, and its vocabulary has seeped into everyday political language. Terms like "Big Brother" and "doublethink" are now shorthand for surveillance and manipulated truth. Orwell wrote the novel while seriously ill with tuberculosis, and it was his final book before his death in 1950.

Why Mandarin leads the native-speaker count

Mandarin Chinese has by far the largest number of native speakers of any language, largely because of China's population. English, by contrast, spreads its speakers across the globe, with far more people using it as a second language than as a first. That distinction between native and total speakers is why the two languages often swap places in rankings.

The thyroid's need for iodine

Iodine is a trace element the body cannot produce, yet the thyroid gland depends on it to make hormones that regulate metabolism. A shortage can lead to an enlarged thyroid, known as a goitre. Many countries add iodine to table salt specifically to prevent deficiency, a public-health measure that has been widely successful.

A planet with a remarkably even climate

Venus has the most uniform temperature of any planet in the solar system, hovering around 460 degrees Celsius across almost its entire surface. A thick atmosphere of carbon dioxide traps heat so effectively that day and night, equator and poles differ very little. That runaway greenhouse effect makes Venus hotter than Mercury, despite being farther from the Sun.