Ontario Grade 9 Science Class Practice Exam

The equation for photosynthesis illustrates the process by which green plants, algae, and some bacteria convert light energy into chemical energy. The correct equation is often represented as:

6CO2 + 6H2O -> C6H12O6 + 6O2.

This shows that carbon dioxide and water, when exposed to light energy, are transformed into glucose (a type of sugar) and oxygen. The glucose produced serves as an energy source for the plant and is a vital part of the food chain, while oxygen is released as a byproduct into the atmosphere, which is essential for the survival of aerobic organisms.

In this equation, the coefficients indicate that six molecules of carbon dioxide react with six molecules of water to produce one molecule of glucose and six molecules of oxygen. This highlights the importance of both carbon dioxide and water in the process of converting light energy into the stored energy found in glucose, and it underlines the ecological significance of photosynthesis in providing energy and oxygen for life on Earth.