(a) The root endodermis plays an essential role during mineral absorption in plants because it have many transport proteins embedded in their plasma membrane.
(b) These proteins are control point where the plant adjust the quantity and types of solutes that it absorbs from the soil. The root endoderm posses the layer of suberin. Suberin layer has the ability to actively transport ion in one direction only. The endodermis regulates the quantity and type of minerals and ions that reach the xylem.