Carbon dioxide is returned to the atmosphere when

During respiration in plants and animals, carbon dioxide is returned to the environment.

Carbon dioxide is a dull gas with a thickness of about 60% which is higher than that of dry air. Carbon dioxide comprises of a carbon particle covalently twofold attached to two oxygen molecules. It is seen in atmosphere in traces.

When organism such as plant, animals, algae and other microorganism respires, it leads to return of carbon dioxide to the environment as it is the major compound formed due to the metabolic activity in them. Apart from this burning of fossil fuels and deforestation also act as cause of returning of carbon dioxide to the environment.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave