Why is it important to know that nitrogen makes up about 80 percent of the Earth's atmosphere?

Knowing that nitrogen constitutes about 80 percent of the atmosphere is important because it helps us understand the balance of gases necessary for life and the role nitrogen plays in various biological and chemical processes.

A strong answer should directly address the approved learning objective to recall that the Earth's atmosphere is about 80 percent nitrogen. This question belongs to The proportions of different gases in the atmosphere within The composition and evolution of the Earth's atmosphere, so the response should use that exact curriculum context rather than a generic statement. The answer is correct when it names the key idea, explains the link to atmosphere, and keeps the wording specific to AQA GCSE revision.