Question

 1. Some organisms can perform gas exchange through diffusion alone. What types of animals can do this? Explain how with each type of animal.

 2. Phylum Arthropoda has special structures that allow air flow. Explain how gas exchange occurs in this phylum?

 3. Explain how book lungs and book gills are similar and different.

 4. Fish gills utilize counter-current gas exchange. Explain what this process is and how it helps fish get enough O2

 5. How do reptile lungs differ from amphibian lungs?

 6. Explain how unidirectional air flow allows for great O2 extraction

Answer 1

Ans. 1. The organism that are unicellular can exchange the gas only through the diffusion process. The organism that exchange the gases only through the diffusion process are the protistan membrane. They are unicellular eukaryotes. In these organism gases are exchanged through the plasma membrane according to the diffusion pressure gredient. It is also found in the sponge, coelenterates, and flateworm. Here direct respiration on the principle of diffusion occurs. It is also called as the body surface respiration.

Ans.2. In phylum Arthropoda, tracheal respiration occurs. It is called as the tracheal respiration. Trachea are the well developed system of external cuticular tube that open outside by 10 pair of spiracles or stigmata on the dorso- lateral margin of the sternum. Each spiracle is bounded by peristreme , the spiracle open behind into atrium. The trafficking of air through spiracles is guided by valves. Most of these spiracles remain closed during expiration in order to prevent the loss of water from body. 5he gas exchange takes places in the walls of tracheoles.