How do roots take in water?
They absorb the water.
What structure transports water and nutrients from the roots to the roots to the rest of the plants?
Normally, the roots take in water and nutrients. The stem moves the water and nutrients to the leaves through a phenomena known as capillary action. This phenomena does not require the roots to work, only the fine tubes in the stem. This is why cut flowers are placed in a vase of water to prolong their life.