How do many unicellular organisms eliminate metabolic wastes, and what is the method of waste removal in complex multicellular organisms?

Many unicellular organisms eliminate metabolic wastes through simple diffusion across their cell membranes. Since these organisms have a relatively high surface area to volume ratio, waste products can easily diffuse out of the cell into the surrounding environment. In complex multicellular organisms, the method of waste removal is more specialized. They have dedicated excretory organs, such as kidneys in vertebrates, which filter blood to remove metabolic by-products. These waste materials are then excreted in a more concentrated form, often in the form of urine, sweat, or respiratory gases, ensuring efficient elimination while maintaining internal homeostasis.