The term biological oxygen transport refers to the incorporation of oxygen from the environment into the cell. It covers all the processes right from breathing to the respiration. Such transport process encompasses different levels of organization from organism to the level of sub cellular organelles. The transport of oxygen in various biological systems majorly depends upon the process of diffusion and convection.
Generally there are two biological systems: plant and animals. Plants do not have any specialized organ for the transport of oxygen. Roots stem and leaves are major sites involved in uptake and release of oxygen. Oxygen is absorbed for respiration and is released into the atmosphere as a result of photosynthesis. Leaves being exposed to air are the major sites of oxygen uptake. Air mixed oxygen enters the empty spaces in the leaves through the openings called stomata. The entry of oxygen to the intracellular air spaces is followed by the process of rapid diffusion. The interior of the cells have less oxygen concentration as compare to the exterior. So, following the principle of diffusion, oxygen moves from the higher exterior concentration to the lower concentration inside the cell. This transport is accomplished by passing through various cellular-barriers such as cell wall and cell membrane. Oxygen being non polar easily diffuses through these barriers.
Oxygen can also be transported through the stem and the roots. The cork of roots and stem contain openings called lenticels, for the transport of oxygen into and out of the plant body. Moreover plants with soft green stems bear stomata for the transport of oxygen.
As far as the transport of oxygen within the plants is concerned, experiments have shown that the plant contains non –tortuous gas filled channels between the stem and the root. Apart from the lenticels; the oxygen requirement