Final answer:
During glycolysis, two ATP molecules are consumed and four are produced per molecule of glucose, leading to a net gain of two ATP (option d). The entire process of aerobic respiration yields about 36 ATP from one glucose molecule when completely oxidized. Glycolysis marks the first stage of cellular respiration.
Step-by-step explanation:
During glycolysis, the number of ATP consumed (per glucose molecule) is two, while the number produced is four. This makes the correct choice (d) two; four. However, it's important to note that there is a net gain of two ATP molecules because two ATP are used up in the early stages of glycolysis. Summing up, by the end of Stage 1 of glycolysis, we have a net gain of:
- Two ATP molecules
- Two NADH molecules
- Two pyruvate molecules
Although a gross of four ATP molecules is produced during glycolysis, two are consumed in the process, therefore leading to a net production of two ATP. After glycolysis, the aerobic cellular respiration continues in the mitochondria, where a larger amount of ATP is produced, amounting to a total net gain of approximately 36 ATP molecules per molecule of glucose when fully oxidized to CO2 and H2O through all stages of respiration.