Final answer:
To make one molecule of glucose during photosynthesis, six molecules of water are needed according to the chemical equation: 6CO2 + 6H2O → C6H12O6 + 6O2.
Step-by-step explanation:
During the process of photosynthesis, to synthesize one molecule of glucose, the chemical reaction involves six molecules of water (H2O). This is explained by the overall photosynthesis chemical equation: 6CO2 + 6H2O → C6H12O6 + 6O2. Here, six molecules of carbon dioxide (CO2) combine with six molecules of water (H2O) in the presence of sunlight to produce one molecule of glucose (C6H12O6) and six molecules of oxygen (O2). So, the answer to how many molecules of water are needed to make one molecule of glucose during photosynthesis is six.