Answer:
Tubules?
Explanation
The trachea, spiracle, and air sac are part of their respiratory system, Howeber, the tubules are what take away the carbon dioxide from their system. Im not sure if they produce the carbon dioixde. But they are a part of what removes the carbon-dioxide from their body.
b) some bacteria reduce nitrate ion
I believe you meant to say is this mistake called a base pair and if that is your question then no. it would be called Mutation. But you can double check that answer.
