Beyond the answers - interesting background to this quiz

The gas that keeps the planet fed

Carbon dioxide makes up only a tiny fraction of the atmosphere, yet it is the raw material plants use to build sugars through photosynthesis. They take it in through small pores in their leaves called stomata and release oxygen as a by-product. This exchange is one reason forests are so important to the global climate system.

A novel born from a family tragedy

Fyodor Dostoevsky wrote "The Brothers Karamazov" after the death of his young son Alyosha, and he named the novel's youngest brother after the boy. Published in instalments in 1880, it was his last novel. Its central story, a father's murder and the moral reckoning that follows, is often read as a meditation on faith, doubt and free will.

An element named after a country

Polonium was discovered in 1898 by Marie and Pierre Curie, who named it after Poland, Marie's homeland, which was then under foreign rule. It is highly radioactive and occurs naturally in trace amounts in uranium ores. Its intense radioactivity makes it useful in anti-static devices, but also notoriously dangerous.

Words built from Greek roots

Melissophobia, the fear of bees, takes its name from "melissa", the Greek word for honeybee. Many phobia names follow this pattern, pairing a Greek or Latin root with "phobos", meaning fear. Aquaphobia, for instance, comes from the Latin word for water, while bacteriophobia refers to an irrational fear of bacteria.

Two capitals with very different histories

Edinburgh has been Scotland's capital since the fifteenth century and grew around its imposing castle, which sits on an extinct volcano. Athens, by contrast, was the centre of ancient Greek civilisation and is one of the world's oldest continuously inhabited cities. Both capitals now balance deep historical roots with modern cultural life.