In the final episode of the series which puts science to the test, Liz looks at how smell works and launches a huge experiment into the nation's sense of smell. Dallas investigates new evidence that the origins of life on earth might have begun in space, while Dr Yan is handing out free wine to the shoppers of Rugby. And on the 25th anniversary of Back to the Future, Jem attempts to build a car that is fuelled by junk.

The programme is co-produced with the Open University. For more ways to put science to the test, go to www.bbc.co.uk/bang and follow the links to The Open University. Show less