Explain the need for ventilation systems in a multicellular organism

Ventilation systems are needed in a multicellular organism to actually obtain oxygen and give out carbon dioxide. Without this ventilation system, it would be very difficult for multicellular organisms to survive. It has been also observed that surface diffusion is not enough for a multicellular organism to breath.

Biochemistry, it deals with the chemical constitution, the breakdown and the synthesis of plant and animal products.

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