I take in and give out, yet I have no mouth. I am crucial for survival, but too much of me can be harmful. What am I?

Category: Science · Difficulty: medium

Hint: Think about breathing.

Answer

A gas exchange

Explanation

Gas exchange is vital for respiration in living organisms, allowing oxygen in and carbon dioxide out.

This is a medium science riddle — a moderate challenge for most people. The answer is A gas exchange.

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