If carbon dioxide and water were abundantly available to a heterotrophic prokaryotic cell, would it be possible for the cell to use them as a food source?

No, it would be impossible

Explanation:

Heterotrophs are so called because they cannot synthesize their own food, they depend on an external source. The synthesis of food is unique to a particular set of organisms called AUTOTROPHS. They have the ability to capture the energy from sunlight using pigments called CHLOROPHYLL and use this energy to synthesize their food in their Chloroplast. This process is called PHOTOSYNTHESIS. Autotophs combine CO2 and H2O (water) to produce glucose (organic molecule).

Heterotrophs like animals, do not possess this ability to capture sunlight energy or fix carbon to produce their food. Hence, in an abundance of CO2 and water, their cells would be unable to utilize these molecules, as only the Chloroplast of autotophs can undergo this process.