Beyond the answers - interesting background to this quiz

The ocean giant that outsizes any dinosaur

The blue whale is not just the largest mammal alive today; it is the largest animal known to have existed, outweighing even the biggest dinosaurs. Its heart alone can be roughly the size of a small car, and its calls travel vast distances underwater. Despite this scale, it feeds on some of the ocean's smallest creatures, filtering krill through baleen plates.

Why the Nile keeps winning the length contest

The Nile has traditionally been named the world's longest river, flowing northward through northeastern Africa before emptying into the Mediterranean. Its precise length has long been debated, partly because the source of the White Nile, in the Great Lakes region, is difficult to pin down. The Amazon is its closest rival, and some measurements have challenged the Nile's title.

Saturn and the art of showing off

Saturn's ring system is the most extensive and spectacular in the solar system, made up of countless particles of ice and rock. Jupiter, Uranus and Neptune also have rings, but they are faint and narrow by comparison. Saturn's rings are so bright that even a modest backyard telescope can reveal them.

A capital that shares its country's name

Bissau is the capital of Guinea-Bissau, a small country on West Africa's Atlantic coast. The name can trip people up because Guinea-Bissau is distinct from its neighbour Guinea, whose capital is Conakry. Praia, meanwhile, is the capital of Cabo Verde, an island nation offshore.

The Sahel: a belt, not a border

The Sahel is a semi-arid band stretching across Africa just south of the Sahara, running from the Atlantic to the Red Sea. Nigeria sits within it, along with countries such as Senegal, Mali, Niger and Chad. The region is known for its dry climate, its grazing lands and the seasonal rains that shape life there.