changes in mass of plants in relation to transpiration

[chloexx]

Hi im uncertain about this experiment which is used in my text book:
Two plants, one with the roots intact and the other with its roots removed are kept in beakers of water in identical conditions
The mass of the plants was measured each hour, and the results showed that the intact plant lost more mass.

Im guessing the main cause of this loss of mass is due to transpiration, but why did the plant with its roots still attached lose more water?
Are there any other causes for the loss of mass in the plants also?

any help much appreciated!