Minerals absorbed by the roots travel up the xylem. How do they reach the parts where they are needed most? Do all the parts of the plant get the same amount of the minerals?
Minerals in the soil cannot all be taken by the plant and need to be regulated. The transportation is different, and sometimes it can be active or passive. Passive transportation occurs through the root hairs, where the special membrane proteins present in the epidermal cells regulate the active movement of nutrients. The transport proteins are also present in the endodermal cells, which help in the restricted uptake of nutrients. The proteins in these cells act as guards and allow selective entry of solutes into the xylem. Moreover, the endodermis; layer of suberin allows only one direction of transport.