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? 1: sunlight would be needed for the reaction to occur, so they would not be a food source. 2: neither carbon dioxide nor water contains energy the cell could use, so they would not be a food source. 3: since carbon dioxide and water are used to make glucose, they could be used as a food source. 4: anything that contains carbon is an organic molecule, so the carbon dioxide could be a food source.