Majorly the intensity of light regulates the temperature.

By utilizing capillary action and the inherent surface tension of water, transpiration pull and cohesion force transport the water by xylem in tall trees.

Sir J.C. Bose (1923) advocated pulsation theory to explain ascent of sap. He proved that the living cells of innermost layer of cortex lying just outside the endodermis were in a state of rhythmic pulsations.

Guttation is the secretion of water, during conditions of high humidity, on to the surface of leaves through specialized pores, or hydathodes. 

Guard cells contain chloroplasts to manufacture the food by photosynthesis, but epidermal cells lack chloroplasts.

Due to the hypertonic nature of salt. Any living cell in such an environment will become plasmolysed (loss of water) and die or become temporarily inactivated.

Root hairs are found only in the zone of maturation, and not the zone of elongation, possibly because any root hairs that arise are sheared off as the root elongates and moves through the soil.

In cactus, stomata close at night to reduce water loss. They lose water when it is open so they open in the day when CO₂ is at its best.

Plasmodesmata are microscopic channels that traverse the cell walls of plant cells enabling the transport and communication between the cells.

 When the cell is fully turgid then the diffusion pressure deficit (DPD) becomes zero to avoid the furthur absorption of water by the cell.

The plant cell is placed in a hypertonic solution, through which plant cell loses water and make the plant cell flaccid and causes the plasmolysis.

The solution having high solute concenteration is known as hypertonic solution.

Levitt (1974) postulate the theory of active potassium ion (K⁺) transport mechanism for opening and closing of stomata.

If a piece of potato tuber is placed in a concentrated sugar solution, it will become limp due to exosmosis (water moves out of the cell).

Ascent of sap is the upward movement of water from the root to the crown. This movement is caused by the attraction of water molecules, i.e. cohesion force.