The mass of some corn plants at the end of their growth period was 6 tons per acre. Most of this mass was produced from?

Most of the mass of corn plants produced at the end of their growth period comes from carbon dioxide (CO2) in the atmosphere. Plants use a process called photosynthesis, where they absorb CO2 from the air through their leaves. The energy from sunlight, captured by the chlorophyll in plant cells, powers a chemical reaction that combines carbon dioxide with water from the soil to produce glucose, a simple sugar, and releases oxygen as a byproduct.

The glucose produced through photosynthesis provides the basic building blocks for growing all parts of the plant, which includes the leaves, stems, roots, and kernels. Over time, the plant converts some of this glucose into more complex sugars, cell wall materials like cellulose, starch stored in the seeds, and other organic compounds that contribute to the overall mass of the plants. Thus, while water and minerals from the soil do contribute to the plant mass, the majority comes from the carbon fixed during photosynthesis, ultimately from CO2.