Chapter 11: Transport in Plants

No. it is not possible because these are responsible for the same. The continuous water column in the xylem vessels for the sap ascent is maintained by the adhesive and the cohesive forces of water. Absence of which would have led to cavitation of xylem vessels or breakage of the water column or the sap movement upwards.

This experiment can demonstrate which tissue is conducting water up the stem. Coloured strands are indicative that the food colour has been conducted upwards through a conducting vessel which is the xylem.

a. This phenomenon is called exosmosis

b. If the filament is replaced in distilled water, then the protoplasm again becomes turgid as water flows in as the shrunken protoplasm swells up or gets deplasmolysed.

The dissolution or diffusion of the solid crystal of sugar does not occur since the number of striking water molecules is less when water is ice cold.

The salt solution being hypertonic causes exo-osmosis in plants. 1 cup salt in 2 cups of water, fairly well dissolved when sprayed on weed plants, start killing them.

Xylem sap: Water and concentration of minerals in dilute form. It is mildly acidic.

Phloem sap: traces of minerals, water, sucrose and amino acids In some species, it also transports fructose or raffinose etc

Tube B shows higher water rise than tube A because the surface area is less in the narrow tube or tube B due to which the surface tension is more in that so the level of rising of water is more in that as well.

Aquaporins are a kind of membrane proteins that form channels in the membrane and are usually facilitating the transport of water between cells. Presence of aquaporins would increase the rate of osmosis thus facilitating it.

a) Abscisic acid is a stress hormone and during stress conditions, it induces changes like the closing of stomata to prevent further water loss during the scarcity of water, aids in seed germination when conditions are favourable and dormancy when not and other changes as and when required.

b) This hormone, abscisic acid gets released in the leaves from the mesophyll cells of the plant.

There is a deprivation of oxygen in the plant roots causing an anaerobic condition. Thus aeration is affected.