The term linchpin is appropriate in describing the termites as they are ecologically important for ecosystem. They play different roles.Termites being decomposers digest the cellulose present in the decaying plant matter, they convert cellulose into reusable form for plants. Termites fix nitrogen by digesting the nutrients in the soil and separates the nitrogen from the attached atoms which is easily taken up by the plants. Termites creates shelter for various insects colonies. They burrow deep inside the soil, creates tunnels suitable for insects colonies living.
Gas exchange occurs at the alveoli in the lungs and takes place by diffusion. The alveoli are surrounded by capillaries so oxygen and carbon dioxide diffuse between the air in the alveoli and the blood in the capillaries.