What challenges did early plants face living on dry land?

What must be true for natural selection to heppen

Photosynthesis uses co2 and cellular respiration produces co2. we call the point when the two processes are in balance--when there is no net production of co2--the compensation point. how might you limit one of the processes in order to achieve a compensation point?

Which component in a graph indicates an independent factor? a. y-axis b. x-axis c. scale