Ace the Ontario Grade 9 Science Exam 2025 – Get Ready to Rock Your Science Socks Off!

Cellular respiration is a metabolic process that occurs in living organisms, where glucose and oxygen are converted into energy, carbon dioxide, and water. This process takes place in the mitochondria of cells and is essential for producing adenosine triphosphate (ATP), which is the primary energy carrier in all biological systems. By using glucose, which is a product of digestion or photosynthesis, and oxygen, which is obtained from the environment, the cells are able to efficiently generate the energy needed for various functions such as growth, movement, and cellular repair.

The confusion with the other options arises from their definitions. The option that mentions converting oxygen into glucose misrepresents the roles of oxygen and glucose in cellular respiration; glucose is not formed from oxygen—instead, glucose is broken down using oxygen. The choice that defines a method of energy production that does not involve oxygen refers to anaerobic respiration, which is distinct from the aerobic process of cellular respiration that occurs with oxygen. Lastly, the mechanism of photosynthesis pertains to the process by which plants convert sunlight into chemical energy using carbon dioxide and water to produce glucose, which is entirely separate from cellular respiration.