plants and conservation of mass

[leeyiren]

U place a pot of plant on a weighing scale in a closed system but light can enter and u water a 500g of water daily. U notice the mass increases. Assuming u minus how much water u added to the system, the pot will still be heavier. So where did the extra mass come from?

The law of conservation of mass is that the mass of a closed system will remain constant over time.

Some1 enlighten me? thx