Mammalia (mammals) have hair or fur and produce milk
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.
Although nitrogen gas makes up 78% of the atmosphere, we can't use it because nitrogen atoms must be broken apart first before. This nitrogen is very much packed and bonded with its atoms and would be useless to use since it can't be used for plants.
