explain the role of Casparian strips found in plants roots in the above two methods of water transport
Answers
Plants need water and minerals to perform photosynthesis and prepare food for their survival. These substances are absorbed by the plant's roots, and then travel inwards from the root surface to the vascular cylinder, from where they travel upwards via the xylem (a type of transportation tissue). These substances travel from the root surface to the vascular cylinder in two ways - apoplastic and symplastic pathways.
An apoplastic pathway is when water and the substances dissolved in it travels from the spaces in the cell wall of one cell to the cell wall of another, without ever entering any cell. The symplastic pathway is when these substances travel from the cytoplasm (material inside cells) of one cell to the cytoplasm of another, through its plasma membrane.
When substances travel inwards from the root epidermis through the cortex, and finally arrive at the endodermis, they encounter the Casparian strip. Since it is an impermeable thickening in the cell wall, it stops materials from traveling through it, thus terminating the apoplastic pathway. Thus, it forces all substances to pass through the cytoplasm by the symplastic pathway. This is very important for the plant, as the cell wall cannot control the type and amount of substances passing through it, but the plasma membrane can. So, by forcing substances to shift from the apoplastic to the symplastic pathway, the Casparian strip allows the plant to control how much water and minerals it absorbs from the soil.
To conclude, it can be said that the Casparian strip is a thickening in parts of the endodermal cell wall, which helps regulate the absorption of water and nutrients from the soil, and also plays an active role in the defense of the plant. However, there are a lot of things about its structure and function that we do not know as yet.
Plants need water and minerals to perform photosynthesis and prepare food for their survival. These substances are absorbed by the plant's roots, and then travel inwards from the root surface to the vascular cylinder, from where they travel upwards via the xylem (a type of transportation tissue). These substances travel from the root surface to the vascular cylinder in two ways - apoplastic and symplastic pathways.
An apoplastic pathway is when water and the substances dissolved in it travels from the spaces in the cell wall of one cell to the cell wall of another, without ever entering any cell. The symplastic pathway is when these substances travel from the cytoplasm (material inside cells) of one cell to the cytoplasm of another, through its plasma membrane.
When substances travel inwards from the root epidermis through the cortex, and finally arrive at the endodermis, they encounter the Casparian strip. Since it is an impermeable thickening in the cell wall, it stops materials from traveling through it, thus terminating the apoplastic pathway. Thus, it forces all substances to pass through the cytoplasm by the symplastic pathway. This is very important for the plant, as the cell wall cannot control the type and amount of substances passing through it, but the plasma membrane can. So, by forcing substances to shift from the apoplastic to the symplastic pathway, the Casparian strip allows the plant to control how much water and minerals it absorbs from the soil.
To conclude, it can be said that the Casparian strip is a thickening in parts of the endodermal cell wall, which helps regulate the absorption of water and nutrients from the soil, and also plays an active role in the defense of the plant.