Answer:
Because they move from a higher concentration area to a lower concentration area.
Step-by-step explanation:
The cells are always trying to balance the intracellular medium with the extracellular medium. For this reason, when the environment outside the cell has a lower nutrient concentration than the concentration within the cell, it is normal for the cell to allow nutrients to escape from the interior to increase the nutrient concentration outside and to keep the nutrients inside and outside. Balanced exterior.
Thus, if a plant cell has a high concentration of phosphorus, for example, but its ester is with a low concentration of phosphorus, the cell will allow phosphorus to escape from its interior so that there is a balance of concentrations of that nutrient.