Importance of diffusion: Diffusion occurs in various physiological functions of an organism. For example , during photosynthesis, plants absorb carbon dioxide from the air and release oxygen. By expanding this vital function, oxygen enters the cell and carbon dioxide is expelled. The water absorbed by the plant evaporates and is expelled from the body in the process of diffusion. During the respiration of animals, the exchange of oxygen and carbon dioxide and the transport of nutrients , oxygen, etc. from the blood to the lymph and transport from the lymph to the cells is accomplished by the diffusion. By This process causes the plant cells to swell. Helps to keep stems and leaves fresh and upright. Flower petals can close or open. Moreover, food may be absorbed in the intestines of animals.