Minerals ener the plant through the soil solution. SOme are passively carried along with the ater that is taken up. Plants can also selectively absorb minerals and accumulate them. This requires active transport across a cell membrane. If it were not for the Casparian strip of endodermis, roots would not be able to actively concentrate minerals into the stele-explain why?
The Casparian strip is a specialized barrier present in the endodermis, a layer of cells in the root of the plant. It is composed of a waxy substance called suberin and is impermeable to water and dissolved minerals. The Casparian strip plays a crucial role in regulating the movement of minerals from the soil into the vascular tissues (stele) of the root.
Without the Casparian strip, minerals could passively move through the cell walls or spaces between cells of the endodermis and enter the stele easily. This would result in a passive flow of minerals, where they would enter the plant indiscriminately depending solely on their concentration in the soil. However, this passive flow would not allow the plant to selectively absorb or accumulate specific minerals that are necessary for its growth and development.
In order for plants to actively transport and accumulate particular minerals, they rely on a mechanism called active transport. Active transport requires energy and involves the movement of substances against their concentration gradient, from an area of low concentration to an area of high concentration. This is necessary to selectively absorb minerals even if their concentration in the soil is low.
The Casparian strip acts as a barrier, forcing minerals to travel through the cells of the endodermis rather than bypassing them. This creates a concentration gradient within the root, with minerals becoming more concentrated in the stele. As a result, active transport mechanisms can be employed by the root cells to selectively absorb and accumulate specific minerals, such as essential nutrients like nitrate ions or iron, which may be present in lower concentrations in the soil.
Therefore, without the Casparian strip, the root would not be able to actively concentrate minerals into the stele, hindering the plant's ability to selectively absorb and accumulate essential minerals for its growth and survival.