Answer:
commensalism
Explanation:
Commensalism is a type of ecological interaction between two species in which one speices benefits while other is unaffected. Commensalism also can be considered as a type of symbiosis-two species that live together. The interaction between human and its microbiota is beneficial for microbiota while it has no effects on humans.
Although, some bacteria (gut bacteria) can help in digestion. In this case, interaction with human is mutualism (both have benefits).
It is body type, cell type, cell structure, nutrition.
Answer:
1. mutation and genetic recombination
