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Multi-Cellular Vs Unicellular Organisms Essay

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 A multi-cellular organisms are organisms that consist of as the name suggests more than one cell in contrast to unicellular organisms that consist of one cell only.
 Multi-cellular organisms are advantageous over unicellular organisms as cell differentiation is present as they carry a variety of cells all with different functions and also it enables the organisms to be more complex due to their larger size.
 Furthermore multi-cellular organisms require specialised organ systems, whereas all the life processes within a unicellular organism take place within that one cell. multi-cellular organisms need organ systems to carry out functions such as: communication between cells including the nervous and circulatory system, to supply
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Oxygen is required for cell respiration with Carbon Dioxide being the waste product. Therefore, organisms must take in oxygen from their surroundings and release Carbon Dioxide back into the environment.

 Unlike multi-cellular organisms, unicellular organisms are able to get a sufficient amount of oxygen through diffusion across the membrane.

 Large animals depend on diffusion to get their oxygen but they require a specialized ventilation system, which serves the function to maintain a concentration gradient, which is necessary for diffusion and to increase the surface area, which consequently speeds up gas
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This is what enables the diffusion of oxygen into the blood and carbon dioxide out of the blood. Multi-cellular organisms have a greater number of cells and therefore a higher energy demand than single cellular organisms, this demand can only be met by allowing the cells to respire, a ventilation system therefore brings oxygen molecules which are a raw product of respiration into the haemoglobin of the blood to then be transported to tissues. Volume ratio is very low so if there was no ventilation system and the organism instead relied on the exchange of materials through the exposed skin it would be very difficult for the body to meet the high energy demand as less oxygen and carbon dioxide would be
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