Q.Name the structures through which gaseous exchange chiefly occurs in

Gaseous Exchange in Plants

Unlike animals, plants do not have specialised respiratory organs or a system to transport gases over long distances. Gaseous exchange in plants is comparatively simple, for several reasons:

• Each plant part (root, stem, leaf) largely takes care of its own gas-exchange needs; there is little transport of gases from one part to another.
• Most cells of a plant have at least a part of their surface in contact with air — through stomata (leaves and green stems), lenticels (woody stems), and the general surface of roots — because of loose packing of parenchyma cells with large intercellular air spaces.
• The rate of respiration in plants is much lower than in animals, so their oxygen demand is modest and can be met by simple diffusion.
• Being non-motile and having a high surface-area-to-volume design, diffusion over short distances suffices.

Therefore oxygen diffuses in and carbon dioxide diffuses out directly across these surfaces without any breathing mechanism, blood or respiratory pigment. Living cells of bark are supplied through lenticels.

This concept covers CET questions on why plants lack respiratory organs and how gaseous exchange is achieved by diffusion through stomata, lenticels and intercellular spaces.

Gaseous exchange in plants is grounded in the NCERT Class 11 Biology curriculum on plant physiology, and "why plants do not have respiratory organs" is a commonly searched question among students. This reasoning-based topic is a recurring important question in NEET and state CET biology papers because it tests conceptual understanding rather than memorised facts.