Cellular respiration is the bunch of metabolic reactions that convert biochemical energy from the glucose or other nutrients into ATP ( adenosine triphosphate) and releases water and carbon dioxide as waste products.
This process has three stages and the very first stage is glycolysis which is taking place in the cytoplasm of the cell. In this stage, the glucose molecule converts into the two molecules of pyruvate and produce energy.
Thus, the correct answer is - cytoplasm of the cell.
The most likely cause of the beak variation is the food source of the finch, the break size and shape was adapted to most likely have easier and better access to food. <span />
