Humber Admissions Practice Test

Which of the following best describes cellular respiration?

1. It occurs only in plants.

2. It produces energy by breaking down glucose.

3. It is a form of photosynthesis.

4. It requires oxygen at all stages.

The correct answer is: It produces energy by breaking down glucose.

The correct choice highlights that cellular respiration is a biochemical process where energy is produced by breaking down glucose. This process occurs in both plants and animals, emphasizing its fundamental role in energy production across different organisms. Cellular respiration involves several stages, including glycolysis, the Krebs cycle, and oxidative phosphorylation, wherein glucose is systematically broken down, releasing energy stored in its molecular bonds. The breakdown of glucose is crucial because it leads to the formation of ATP (adenosine triphosphate), which cells utilize as a primary energy currency for various biological activities. This process can occur both aerobically, in the presence of oxygen, and anaerobically, in the absence of oxygen, providing flexibility in energy production depending on environmental conditions. In contrast, other choices do not adequately capture the essence of cellular respiration. For instance, stating that it occurs only in plants is inaccurate because it also takes place in animal cells. Describing cellular respiration as a form of photosynthesis is misleading since photosynthesis is the process by which plants convert sunlight into energy, which is the opposite of what cellular respiration accomplishes. Lastly, asserting that it requires oxygen at all stages overlooks the fact that some stages, such as glycolysis, can occur without oxygen. Thus, the definition of cellular