Main function of lenticels is:

Question

Accepted Answer

The correct option is 3:

Lenticels are specialized, porous areas found on the bark of woody stems and roots, as well as on certain fruits. Unlike stomata, which are regulated by guard cells and can open or close, lenticels are always open. Their primary function is to facilitate the direct exchange of gases between the internal tissues of the plant and the external atmosphere. This process is crucial for the respiration of cells within the stem, especially in older, secondary tissues where the epidermis has been replaced by bark, which is impermeable to gases. Through these small, raised pores, oxygen can diffuse into the plant, and carbon dioxide and water vapor can be released, ensuring that the living cells beneath the bark receive the necessary gases for their metabolic activities.

The incorrect option is 1: Guttation. Guttation is the exudation of xylem sap from the tips or edges of leaves in some vascular plants, typically occurring when root pressure is high and transpiration is low. It's a process primarily associated with leaves, not the lenticels on stems.

The incorrect option is 2: Transpiration. Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems, and flowers. While lenticels do allow some water vapor to escape, the primary sites for transpiration are stomata on leaves, and the main role of lenticels is gas exchange.

The incorrect option is 4: Bleeding. Bleeding, also known as sap exudation, refers to the flow of sap from a cut or wound on a plant. This phenomenon is a result of positive root pressure or turgor pressure within the plant, and while sap might exit through a wound near a lenticel, lenticels themselves are not designed for or primarily involved in this process.