Why water is a polar molecule?

and What property of water explains why it can travel to the the top of trees???

PLEASE HELP

In addition, the the properties of water that are mechanically ... distance the water has to travel by taking the most direct route to the top of the tree. ...

If water were not a polar molecule and could not form hydrogen bonds, how would this change the structure and density of ice? Why would change? How would this affect the organisms living in lakes and ponds?