Question

why diffusion insufficient to meet the oxygen requirement of large animals

Answer 1

Due to thick skin of animals

Answer 2

unlike unicellular organisms, complex or cellular organisms have complex body design, with specialised tissue to perform various necessory functions of the body. since these cells are not in direct contact with the surrounding environment so simple diffusion cannot meet the oxygen requirements of all these cells.

thank you, please mark my answer as brainliest.