Is carbon present in all organisms and in the atmosphere?

Yes, carbon is a fundamental element present in all known organisms, as it is a key component of organic molecules such as proteins, lipids, carbohydrates, and nucleic acids. In the atmosphere, carbon is primarily found in the form of carbon dioxide (CO2), which plays a crucial role in the Earth's carbon cycle and is vital for photosynthesis in plants. Thus, carbon serves as a critical building block for life and is integral to various biological and ecological processes.