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Write a comparative outline of gaseous exchange in a protozoan, an earthworm and a bony fish
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Write a comparative outline of gaseous exchange in a protozoan, an earthworm and a bony fish (20) All organisms need exchange and transport systems. The gaseous exchange requirements increases as the organism increases in size and complexity. Demands for water, oxygen and nutrient molecules increases with the size. Acellular organisms are active in wet conditions only. Their surface is permeable to oxygen, carbon dioxide and water. They have a large surface area to volume ratio, and diffusion distances in their body are small. Annelida, such as the earthworm, have long, thin, segmented bodies, consisting of three different layers of cells. The surface area to volume ratio is quite large, and diffusion distances are long. Chordates, such as fish, are also made up of three layers of cells. Their surface area to volume ratio is small, and the diffusion distances are very large. In both earthworms and fish, an efficient transport...
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