Which of the following is not a use of nitrogen?

The following are the uses of nitrogen:

• Nitrogen is needed by plants to grow properly as it is a component of chlorophyll.
• Nitrogen is also an important component of proteins and amino acids which are part of DNA and thus, nitrogen plays important role in the growth of humans and animals also.
• Nitrogen being unreactive is also used in food industry to preserve food.

But it has no role in respiration, so it is not the use of nitrogen.