AP BIOLOGY

PLANTS

TRANSPORT IN PLANTS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The primary function of casparian strips is to-
A
force water and minerals through the membranes of endodermal cells
B
prevent entry into the xylem solely through the apoplast
C
provide regulation for water and minerals movement in the plants
D
prevent entry into the xylem from the symplast
Explanation: 

Detailed explanation-1: -Explanation : Suberin is a waxy substance that is present on the walls of the endodermal cells. The region which confines the waxy substance is the Casparian strip. It forces the water content and solutes to cross the plasma membranes of endodermal cells and does not allow it to slip between the cells.

Detailed explanation-2: -Casparian strips form a barrier to the apoplastic flux, forcing ions to pass through the selectively permeable plasma membrane into the cytoplasm, rather than move along the cell wall.

Detailed explanation-3: -The casparian strip does not allow the water to penetrate it as the suberin is impermeable to water. As a result the water moves through the symplastic pathway that is through the plasmodesmata of the cells to reach the cells of the xylem.

Detailed explanation-4: -What important role does the Casparian strip play in the movement of water through plants? Forces water to move through the cytoplasm of living endodermal cells as it makes its way from the soil to the xylem.

There is 1 question to complete.