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By manipulating young plants, scientists have finally worked out the mechanism by which sunflowers move their stems and leaves to face the sun. Starting in the east in the morning, tracking the sun through the sky, the plants make sure they get the most sunlight all day. And it is all thanks to their internal clocks, their circadian rhythm. Marnie Chesterton talks to Stacey Harmer, Professor of Plant Biology at University of California, Davis and who is the author of the paper just published in the journal Science this week.

Queen Bee Control
Bee hives have evolved to have a complex, fascinating social hierarchy, and although we know about Royal Jelly and pheromones, how exactly does the queen bee control the fertility of the rest of the hive? Adam Rutherford talks to New Zealand geneticists, Peter Dearden and Elizabeth Duncan, who has finally worked it out.

Olympic Access
Getting around the city of Rio de Janeiro for the Olympic and Paralympic Games is still tricky for disabled athletes and spectators – in spite of improvements carried out. Money has been invested into making public transport accessible since the city won the right to host the Games. But wheelchair users and other disabled tourists face a number of obstacles when exploring the city because of badly maintained pavements and a lack of ramps to make crossing the roads easier.

Robofish
About 400 million years ago, life on Earth looked rather different. The seas were teeming with creatures big and small, but only plants – plus the odd millipede and scorpion – had made it onto land. Imagine you were one of the very first adventurous amphibians. How would you haul yourself out of the shallows? ´óÏó´«Ã½ Science reporter Jonathan Webb has been talking through the possibilities with scientists in Atlanta in the United States.

Technology and Human Failure
In the search for better ways to deliver healthcare, Dr Kevin Fong has been asking what medicine can learn from how other fields where lives are also on the line make high performance systems work safely and reliably. One organisation that might have valuable lessons for medicine is NASA, where the history of human space exploration has proven to be the scene of both its greatest triumphs, such as the Apollo Moon landings, as well as its greatest disasters, such as the Challenger and Columbia Shuttle explosions. Kevin hears about the technological and human roles in both those momentous events and what can be learned from them.

How Whales Hear
Whales use more than just their ears to hear. Since their early ancestors first walked back into the water, the evolution of whale hearing and sound production has been fascinating, Dr Ben Garrod regales Marnie Chesterton with facts about whale communication and evolution, including why toothed-whales have asymmetric jaws and can stun their prey with ultrasonic sound.

(Photo credit: The sun shines down on a sunflower © Jens Schlueter/AFP/Getty Images)

The Science Hour was presented by Claudia Hammond with comments from David Robson of ´óÏó´«Ã½ Future

Producer: Rami Tzabar