How do plants know which way is up?

How can you use sticks to calculate the circumference of the Earth? Can exfoliators remove your fingerprints? How do plants know which way is up? What dictates the pattern of a cat's stripes? What are hiccups? Can mosquitoes see you? Dr Chris Smith and Dan Corder have all the answers... Like this podcast? Please help us by supporting the Naked Scientists (thenakedscientists.com/donate)