Plant Transport and Physiology

Lateral meristems surround the established stem of a plant and cause it to grow laterally (larger in diameter). Vascular cambium produces secondary xylem and secondary phloem.

As K⁺ levels increase in the guard cells, the water potential of the guard cells drops, and water enters the guard cells. The loss of water by the guard cells causes them to become flaccid and the stomatal opening to close.

Correct Answer: Capillary water

The actual pressure with which a cell absorbs water is called suction pressure.

When the movement occurs due to faster growth on the upper surface of an organ, it is said to be epinastic movement.

Example: Opening of floral buds

In plants, excess water is removed in the form of water vapours by the process of transpiration.

In a plant, the maximum water loss takes place through transpiration from stomata.

Phloem helps in translocation of food in plants.

The opening of stomata occurs due to the influx of K⁺ ions into the guard cells. The source of K⁺ ions are the neighbouring subsidiary and epidermal cells. It increases the concentration from 50 mM to 300 mM in guard cells. The increase in K⁺ ion concentration increases the osmotic concentration of guard cells. It leads to stomatal opening. ATP helps in entry of K⁺ ions into the guard cells.

The cohesion of water explains only maintenance of the sap column. The explanation for the upward movement of the water is accounted for by a mechanism, called transpiration pull, that involves the evaporation of water from leaves. It is the most accepted theory for ascent of sap.

In plants, adhesion forces water up the columns of cells in the xylem.

Vernalisation is the induction of a plant's flowering process by exposure to the prolonged cold of winter or by an artificial equivalent.

Transpiration is the process in which there is loss of water in the form of vapours from  plants.

Opening and closing of stomata is controlled by guard cells.

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