The examined tissue could be cortex, due to the fact that it's rigid and does not require oxygen, so metabolic processes, like respiration, are not happening. The cortex, or wood, is dead tissue that no longer develops metabolic processes. It starts growing as the plan also grows, and the cambium tissue is in charge of this process.
Yes, this is true because some bacteria in our environment tends to either fend off of or kill other types of bacteria. In this case, this bacteria is helpful because it turns gaseous nitrogen into a form that can be absorbed and used by plants in our environment.
