Problem:
Question 1: What are the key environmental conditions that shape the diversity of microbes in the gastrointestinal tract?
Question 2: List four functional activities of the normal human microbiome, useful to their human hosts, that have been used to suggest that the gut microbiome is an "organ" in its own right.
Question 3: Identify some undesirable side effects of a nonoptimal gut microbiome, from the human perspective.
Provide a brief explanation for your answer.