No, it isn't.
Calculate the molecules of making up the entire atmosphere and then strike off the zeros.
Besides, there is no "layer"
The carbon cycle. Is that basics not even taught. Are ANY systems taught anymore. No, just one piece of the cycle.
Where is the biology discussion? where is that in the “model”
When I took botany the research showed plants were carbon starved. If we wanted to increase plant growth in a greenhouse, we pumped co2 in it because lack of co2 was a plant growth limiter. In fact, plants had a secondary high energy use photosynthetic mechanism to capture c02.