I think the respiratory system and circulatory system
Answer:
Simple epithelium is a single layer of cells with every cell in direct contact with the basement membrane that separates it from the underlying connective tissue. In general, it is found where absorption and filtration occur. The thinness of the epithelial barrier facilitates these processes.
Explanation:
Protein I think is the answer for this question.
THIS TYPE OF RELATIONSHIP IS CALLED "COMMENSALISM"
