Ecology Science Olympiad Practice Test 2026 - Free Ecology Practice Questions and Study Guide

Respiration plays a vital role in the carbon cycle by releasing carbon dioxide (CO2) back into the atmosphere. This process occurs in both plants and animals. During respiration, organic compounds such as glucose are broken down for energy, and as a byproduct of this chemical reaction, CO2 is generated. This released carbon dioxide can then be utilized by plants during photosynthesis, where it is converted into organic matter, effectively allowing the cycle to continue.

While carbon fixation involves capturing atmospheric carbon to form organic molecules, respiration serves the integral function of returning carbon to the atmosphere, thus maintaining the balance of carbon within ecosystems. The other options do not accurately depict the role of respiration in the carbon cycle, as they refer to processes not directly related to the release of carbon dioxide.