What will happen if plants do not get carbon dioxide?

If plants don't get carbon dioxide, they won't be able to take water from the soil to get sugar from sunlight; this sugar is called "Glucose" which is food for a plant, and plants need sugar so they can break it down to get the energy that they need to avoid wilting.

Carbon dioxide enters the plant through the leaves and comes back out of the plant as oxygen from the water in the soil, and the carbon dioxide turns into sugar