Cam plants function using crassulacean acid metabolism. like c4 plants, cam plants provide preparatory step for the calvin cycle. cam plants are found in hot, dry environments; to prevent desiccation, they keep their stomata closed during the day. they take in carbon dioxide at night while stomata are open. to increase the concentration of carbon dioxide available to the enzyme rubisco and minimize the degree of photorespiration, the cam plants carboxylate

ORGANIC ACIDS  

Explanation:

CAM PLANTS CARBOXYLATE ORGANICS ACIDS through the addition of  CO2 to PEP Carboxylase(  a phosphoenolpyruvate carboxylase enzyme present in the mesophyll cells of the cytoplasm in a green plant) to produce Oxaloacetate (organic compound).

CO2 + PEP  ⇒ C4H4O5 (oxaloacetate)

Oxaloacetate is then converted to a similar molecule, Malate (C4H6O5,  another form of organic compound) that can be transported in to the bundle-sheath cells. Malate enters the plasmodesmata and releases the CO2. The CO2 then fixed by rubisco and made into sugars via the Calvin cycle.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.