Beyond the answers - interesting background to this quiz

The river that drains a continent

The Amazon carries more water than any other river on Earth, and its basin covers a huge share of South America. While the river's mouth and much of its main course lie in Brazil, the headwaters rise in the Andes, and the river also flows through Peru and Colombia. Ecuador, one of the options in the quiz, shares the Amazon basin but not the river's main channel.

The animals that missed the zodiac

The Chinese zodiac cycles through twelve animals, including the monkey, the dog, the rat and the dragon. The turtle is not among them, despite being a powerful symbol in Chinese culture, associated with longevity and wisdom. The twelve-year cycle is tied to the lunar calendar, which is why Chinese New Year falls on a different date each year.

A city where continents meet

Baku, the capital of Azerbaijan, sits on the western shore of the Caspian Sea, in the region known as the South Caucasus. Geographically it lies in Asia, though the country is often grouped with Europe in political and cultural contexts. The Caspian itself is the world's largest inland body of water, sometimes described as a sea and sometimes as a lake.

The Sahel, a belt of transition

The Sahel is a semi-arid strip of land running across Africa, south of the Sahara and north of the savannas. Mali is one of the countries it passes through, along with Niger, Chad and Sudan. The region faces recurring drought and desertification, making it one of the most environmentally fragile areas on the planet.

Why sunlight matters to your bones

When ultraviolet light hits the skin, the body begins producing vitamin D, which helps the intestines absorb calcium and phosphate. A short time in the sun is often enough for many people, though the amount depends on latitude, season and skin tone. Vitamin D is also found in oily fish, egg yolks and fortified foods.