Question

CO2 concentrations in the atmosphere increased from less than 300 ppmV in the early 1900s to over 330 ppmV Towards the ends of that century. Researchers have used her barium records and fossilized leaf specimens to measure changes the density of stomata over that time. The results of one such analysis in conifers are shown below. Describe the results and explain how this relationship relates to the role of stomata in the evolution of plants to life on land.

Answer 1

The graph shows that, with more CO2 concentration, there are fewer stomata in the leaves.

Stomata are used by plants for gas exchange and also for water diffusion. Having fewer stomata is a way to regulate the quantity of CO2 that enters the cell and also a way to reduce water loss.

This means that stomata allowed plants to establish inland without losing water, a big challenge for them.