Biology Regents Practice Exam 2025 - Free Practice Questions and Study Guide

The significance of the carbon cycle lies in its crucial role in regulating climate and supporting life on Earth. This cycle involves the continuous movement of carbon among the atmosphere, land, water, and living organisms.

Carbon dioxide, which is part of the cycle, plays a critical role in photosynthesis—the process by which plants, algae, and some bacteria convert sunlight into energy, releasing oxygen as a byproduct. This not only supports the growth of these organisms but also sustains the broader ecosystem, as they serve as the foundational producers for various food chains.

Furthermore, the carbon cycle helps regulate Earth's temperature through the greenhouse effect. Carbon dioxide and other greenhouse gases trap heat in the atmosphere, thereby playing a pivotal role in maintaining a stable climate suitable for various forms of life. If the balance of this cycle is disrupted, it can lead to significant climate changes, impacting weather patterns and habitats.

The other options do not address the full breadth of significance that the carbon cycle has in terms of its essential contributions to life and climate stability. For instance, while changes in the carbon cycle can influence extinction events, this is not its fundamental role. Similarly, the carbon cycle does not primarily function to regulate atmospheric oxygen levels or ocean salinity. Thus, recognizing the carbon cycle