Aplant's roots may take up water and salts less efficiently from a waterlogged soil than from the a fairly dry soil suggest reason for this
Answers
Explanation:
In order for a plant to take up water from the soil the following needs to happen: Water and mineral enter through root epidermis, cross the cortex, pass into the stele, and are carried upward in the xylem. The cells cannot get enough mineral ions from the soil by diffusion alone. The soils solution is too dilute.
Active transport of these ions must occur. Specific carrier proteins in the plasma membrane attract and carry their specific mineral into the cell. A Proton Pump: H+ is pumped out of the cell causing a change in pH and a voltage across the membrane. This helps drive the anions and cations into the cell. Water and minerals cross the cortex in one of 2 ways: Via Symplast which is the living continuum of cytoplasm connected by plasmodesmata. Via apoplast which is nonliving matrix of cell walls. At the endodermis the apoplastic route is blocked by the CASPARIAN STRIP. this is a ring of suberin around each endodermal cell. Here water and minerals MUST enter the stele through the cells of the endodermis. Water and minerals enter the stele via symplast, but xylem is part of the apoplast. Transfer cells selectively pump ions out of the symplast into the apoplast so they may enter the xylem. This action requires energy.