Beyond the answers - interesting background to this quiz

Why Bangkok's full name never fits on a form

Most of us know Thailand's capital as Bangkok, but Thais themselves usually call it Krung Thep Maha Nakhon, the shortened version of a ceremonial name that runs to well over a hundred letters and is often listed as the longest place name in the world. The name Bangkok is thought to derive from an older settlement meaning something like "village of wild plums". It is a reminder that the names we use for cities are often not the ones their own residents use.

The quiet engine of photosynthesis

Photosynthesis is usually explained as plants taking in carbon dioxide and releasing oxygen, which is true, but the oxygen comes from water, not from carbon dioxide. Plants split water molecules using energy captured from sunlight, and the oxygen is essentially a by-product. That by-product happens to be the reason complex animal life, including us, can exist on this planet.

Why Canberra exists at all

Sydney is far larger and better known, but Australia's capital is Canberra, and that was a deliberate compromise. When the colonies federated in 1901, Sydney and Melbourne both wanted to be the capital, so a purpose-built city was placed between them in New South Wales. American architect Walter Burley Griffin won the international design competition for the city, which is why Canberra's layout looks so different from most Australian cities.

Tempo markings that tell you to speed up

Accelerando is the Italian term for gradually getting faster, and it belongs to a family of tempo directions that also includes allegro, which means fast and lively, and andante, which means at a walking pace. These words survive in sheet music because Italian musicians and publishers dominated European music printing for centuries. A conductor reading accelerando knows the beat should tighten, not jump.

Four states and one very shallow lake

Lake Erie is bordered by four US states: Ohio, Pennsylvania, New York and Michigan. It is the shallowest of the Great Lakes, which makes it warm quickly in summer but also unusually vulnerable to pollution and algae blooms. Its depth is also why it can turn dangerous fast in a storm, with waves that build up in a short distance.